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EK-PWR20-SD-001

April 1976

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Document:	DECsystem20 Power System System Description
Order Number:	EK-PWR20-SD
Revision:	001
Pages:	137
Original Filename:	EK-PWR20-SD-001_DEC20_PowerSysDescr_Apr76.pdf

OCR Text

EK-PWR20-SD-001

decsuUscen2c
POWER SYSTEM

SYSTEM DESCRIPTION

digital equipment corporation « marlborough, massachusetts

EK-PWR20-SD-001

POWER SYSTEM

SYSTEM DESCRIPTION

digital equipment corporation - marilborough, massachusetts

lst Printing Jan.1976
2nd Printing Apr.1976

The

drawing

are

the

and

Corporation

and

copied

the

equipment

written

The

specifications

property
or

basis

Digital

shall

not

used

for

the

hercin

Equipment

reproduced

whole

manufacturc

described

herein

part

sale

without

permission

material

purposes and

this manual

is for informational

is subject to change without notice.

Digital Equipment Corporation assumes no responsibility

for any errors which

may appear in this

manual,

Printed in U.S.A.

The following are trademarks of Digital Equipment

Corporation, Maynard, Massachusetts:
DEC

DECtape

DECCOMM

DECUS

RSTS

DECsystem-10

DIGITAL

TYPESET-8

DECSYSTEM-20

MASSBUS

TYPESET-11

PDP

UNIBUS

CONTENTS
Page

CHAPTER 1

SYSTEM LEVEL DESCRIPTION

1.1

PHYSICAL DESCRIPTION

1.2

MAJOR COMPONENT FUNCTIONS AND LOCATIONS

1.3

ELECTRICAL CHARACTERISTIC SUMMARY

1.4

ELECTRICAL REQUIREMENTS

1.5

ENGINEERING DRAWINGS

CHAPTER 2

INTERFACE LEVEL DESCRIPTION

2.1

BLOCK DIAGRAM ANALYSIS

2.2

BASIC OPERATION

2.3

SWITCH PANEL

2.3.1

2.3.2

PWR20/2-1
PWR20/2-5
PWR20/2-6

PWR20/2-8

Operation

POWER-FAJLURE PROTECTION

2.5

AUTOMATIC RESTART

CHAPTER 3

UNIT LEVEL DESCRIPTION

INTRODUCTION

3.2

863 POWER CONTROL

3.2.1

Block Diagram Analysis

3.2.2

Detailed Circuit Description

PWR20/3-1
PWR20/3-3
PWR20/3-3

W7000 Auxiliary Power Supply

324

W516 AC Low Voltage Detector

3.3

G8017 Indicator Driver

3.3.1

Block Diagram Analysis
Detailed Circuit Description

333

34
34.1

34.1.1
34.1.2
34.13

34.1.4
3.5

3.5.1
3.5.1.1

35.1.2
3.5.13

3.6
3.6.1
36.1.1

3.6.1.2
3.6.1.3

3.7

3.7.1
3.7.1.1

PWR20/3-6

PWR20/3-21
PWR20/3-24

PWR20/3-25

861-D POWER CONTROL

3.3.2

PWR20/2-10
PWR20/2-10
PWR20/2-12

3.23
3.2.5

PWR20/14

PWR20/14
PWR20/1-13

System Connections

3.1

PWR20/1-1
PWR20/1-1

PWR20/3-28
PWR20/3-28

Pilot Control Board Circuit Description
H7420 POWER SUPPLY

PWR20/3-30

PWR20/3-33

PWR20/3-35

Detailed Circuit Description
H7420 Step-Down Transformer
H7420 +15 Volt Output

H7420 Clock Output
H7420 AC LO and DC LO Sensing Circuits

H744 +5 VOLT REGULATOR

PWR20/3-35

PWR20/3-35
PWR20/3-37
PWR20/341

PWR20/3-41
PWR20/3-46

Detailed Circuit Description
H744 +5V Regulator Circuit

H744 Overcurrent Sensing Circuit
H744 Overvoltage Crobar Circuit

H745-15 VOLT REGULATOR
H745 Detailed Circuit Description

H745 -15 Volt Regulator Circuit
H745 Overcurrent Sensing Circuit
H745 Overvoltage Protection
H754 +20, -5 VOLT REGULATOR

Detailed Circuit Description
H754 +20, -5V Regulator Circuit

PWR20/iii

PWR20/3-46

PWR20/3-46
PWR20/3-51
PWR20/3-52

PWR20/3-53
PWR20/3-53

PWR20/3-53
PWR20/3-58

PWR?20/3-58
PWR20/3-60

PWR20/3-60

CONTENTS (Cont)
Page

3.7.1.2

H754 Overcurrent Sensing Circuit

PWR20/3-64

3.7.1.3

H754 Overvoltage Crobar Circuits

PWR20/3-65

3.7.1.4
3.8
3.8.1

H754 Voltage Adjustments

H770 +15 VOLT REGULATOR

PWR20/3-66
PWR20/3-67

Detailed Circuit Description

PWR20/3-67

H770 +15V Regulator Circuit

PWR20/3-67

3.8.1.2

H770 Overcurrent Sensing

PWR20/3-72

38.1.3

H770 Overvoltage Crobar Circuit

PWR10/3-73

38.1.1

3.9
39.1
3.10

3.10.1
3.11
3.11.1

H760 POWER SUPPLY

PWR20/3-74

Detailed Circuit Description

PWR20/3-74

CAPACITOR ASSEMBLY

PWR20/3-78

Detailed Circuit Schematic

PWR20/3-78

H761 SERIES PASS ASSEMBLY

PWR20/3-80

Detailed Circuit Description

PWR20/3-80

3.11.1.1

+10V Reference (G8013)

PWR20/3-82

3.11.1.2

-5.2 Vdc Controls (G8010)

PWR20/3-85

3.11.1.3

-2.0 Vdc Controls (G8011)

PWR20/3-87

3.11.1.4

-5.2 V Heat Sink Assembly

PWR20/3-90

3.11.1.5

-2.0V Heat Sink Assembly

PWR?20/3-92

3.11.1.6

DC Low Voltage Detector (G8014)

PWR20/3-95

3.12

AIR FLOW SENSORS

PWR20/3-97

ILLUSTRATIONS
Figure No.

Title

Page

1-1

Basic 2040 Configuration

PWR20/1-2

1-2

Front View — Power Supply and Cooling Assembly Locations

PWR20/1-5
PWR20/1-6

1-3

Rear View — Power Supply and Cooling Assembly Locations

CPU and I/O Cabinet Rear Door (Open)

PWR20/1-7

1-5

KL10-C Power Distribution System Block Diagram (System Level)

PWR20/1-8

2-1

KL10-C Power Distribution System Block Diagram (Interface Level)

PWR20/2-2

2-2

Front View of Switch Panel

PWR20/2-7

2-3

Switch Panel, External Connections

PWR20/2-9

3-1

KL10-C Power Distribution System Block Diagram (Unit Level)

PWR20/3-2

3-2

863 Power Control, Block Diagram

PWR20/34
PWR20/3-7

3-3

863 Power Control Simplified Functional Schematic

863 Power Control, Power Down Sequencing

PWR20/3-18

3-5

NESSS Timer, Simplified Block Diagram

PWR20/3-26

3-6

861-D Power Control, Block Diagram

PWR20/3-29

3-7

861-D Simplified Functional Schematic

PWR20/3-31

3-8

H7420 Power Supply, Simplified Schematic

PWR20/3-36

H7420 AC LO and DC LO Sensing Circuits, Simplified Diagram

PWR20/3-42

3-10

H7420 Power-Up and Power-Down Sequencing

PWR20/3-45

3-11

H744 Precision Voltage Regulator E1, Simplified Diagram

PWR20/3-47

3-12

H744 Regulator Wavetorms

PWR?20/3-50

3-13

H745 Precision Voltage Regulator E1, Simplified Diagram

PWR20/3-54

PWR20/iv

ILLUSTRATIONS (Cont)

Figure No.

Title

3-14

H745 Regulator Waveforms

3-15

H754 Precision Voltage Regulator E1, Simplified Diagram

Page

PWR20/3-57
PWR20/3-61

3-16

H770 Precision Voltage Regulator E1, Simplified Diagram

3-17

PWR20/3-68

H770 Regulator Waveforms

PWR20/3-71

3-18

H760A Power Supply, Simplified Schematic

3-19

Distribution of Power to Fans in H760A and H760B

3-20

PWR20/3-77

Capacitor Discharge Curve

3-21

H761 Regulated Series Pass Assembly, Simplified Diagram

PWR20/3-79

3-22

+10 V Reference, Simplified Schematic of +REF C Circuit

3-23

PWR20/3-84

Typical G8O10 -5.2 Vdc Control Circuit, Simplified Schematic

3-24

PWR20/3-86

Typical G8011 -2.0 Vdc Control Circuit, Simplified Schematic

3-25

PWR20/3-8%

Typical -5.2 V Heat Sink, Simplified Schematic

PWR20/3-91

3-26

Typical -2.0 Vdc Heat Sink, Simplified Schematic

3-27

Air Flow Sensor Characteristics

PWR20/3-76

PWR20/3-81

PWR20/3-93

PWR20/3-98

TABLES

Table No.

Title

Page

1-1

Power Supplies, Regulators and Controls

PWR20/1-3

1-2

KL10-C System Power Requirements

PWR20/1-9

1-3

Electrical Characteristics Summary

PWR20/1-10

Reference Drawings

PWR20/1-14

PWR20/v

FOREWORD

This

manual

description

modularly-structured

(operation

serves

used

with

theory)

the

DECsystem=-20

integral

part

technical
2040

Power

KL-based

system

total

System.

documentation,

documentation

package.

multi-level

this

manual;

that

form
it

three

integrated

Level

level

Section

the

power

what

the

pertinent

System

level

implemented

nature

expansion.

levels

which

each

The

provide

level

structure
a

totally

description:

Also

the

2040

each

Power

descriptions

System

KL-based

power
is

supply,

basic

system

consists

schematics

are
is

which

system

Processor
power

block

interconnections.
The

characteristics
unit

contains

differ

detail.

provided

system

power

typical

location

Electrical

modular

presentation

describes

regulator.

future

presentation

and

describes

physical

open-ended

Level

Unit

context

structure

Level

Interface

Each

for

Power

System

document

exhibits

suitable

comprises

and

shows

the

controller

and

diagram

discussion

what

tabulated

provided.

and

each

and

level.

which

shows

includes

component

list

all

does.

Section 2 discusses the power system on an interface level,

based on a more detailed version of the block diagram provided
in Section 1; major signals and voltages are introduced. The

discussion at this level follows sequential
down)

operations through the block diagram.

(e.g., power/up
The level of text

does not go beyond the level of the block diagram.

Section 3 describes the unit level theory. Here, the previously

used system block diagram is further detailed to show all the
signals and voltages produced. From this, detailed theory of
each Power System component is provided;
schematic diagrams complement the text.

simplified block and
All diagrams are

compatible with those in the system and interface level
descriptions.

Included in a series of KL-based documentation,

this manual

relates only to the 2040 Power System. For further information
on the 2040 system,

refer to the Introduction to KL-Based

System Technical Description manual

(EK-KL10-TD-002) .

CHAPTER
SYSTEM

This

1
LEVEL

chapter

basic

DESCRIPTION

briefly

physical

describes

Presented,

are

and

components

block

diagrams

and

1.1

PHYSICAL

DESCRIPTION

KL10-C

KL-based

description

power

The

the

defined

tabular

Processor

2040

Power

where

all

major

through

the

use

KL10-C

Processor)

used

comprises

three

supplies.

the

power

from

Console

controls

shown

adjoining

viewed

PDP-11/40

and

all

DECsystem-20

the

Processor

associated

KL-based

Floppy

input/output

cabinet

contains

the

Central

cable,

which

Processor

connects

cabinet.

independent

power

interconnected
common

DEC

MAJOR

Table

1-1

the

KL10-C

COMPONENT

lists

Power

and

basic

Control

the

861

System;

logic;

Power

proéessor

and

power

contains

peripherals,

system;

the

right

own

center

Unit.

its

Control

peripherals

connections.

power

The

cabinet

and

has

KL10-C

They

control

power

the

Console

have

are

system

via

Bus.

FUNCTIONS

power

end)

disk

terminal

general,

the

left

Processing

the

cables

with

Power

1.2

1-1.

(including

self-contained

the

(front

the

DECwriter

with

front,

contains

"stand-alone"

Figure

cabinets

cabinet

The

specifications.

2040 configurations. A typical system configfiration
the

System.

AND

supplies,

the

LOCATIONS

regulators

Physical

PWR20/1-1

locations

and

are

controls

shown

CONSOLE
PROCESSOR

170

CPU

CABINET

RH20

CPU

DTE20

SYSTEM

DIA20

MAZ0

DMA20

POP-11/40

MA20

(LOGIC)

{(LOGIC)

11 -PERIPHERALS

DEC_POWER CONTROL BUS
10-2203

Figure

1-1

Basic

2040

Configuration

PWR20/1-2

Table 1-1
Power Supplies, Regulators and Controls

Quantity

Assembly

Function

863D/E Power Control

Main Power Control for system

861D/E Power Control

Power control for console processor equipment

S(7)*

H7420 Power Supply

Main power supplies for CPU. RH20, DTE20,
DIA/DMA20, and MA20

H760 Power Supply

Power supply used with capacitor assembly (7009878)
to provide -11 and +15 Vdc to the H761 Series Pass

Assembly
1

15(19)*

H761 Series Pass Assembly

H744 Regulator

Regulated -5.2 and -2.0 Vdc to the CPU

Regulated +5 Vdc to CPU, DTE20, DIA20, DMA20,
and the MA20

H745 Regulator

Regulated -15 Vdc to DIA20 and DMA20

6(12)*

H754 Regulator

+20. -5 Vdc to the MA20

H770 Regulator

+15 Vdc to air flow sensors

Switch Panel

Contains power on/off controls (normal and
emergency) and bootstrap loading controls.

*If second MA20 is used, number in parentheses indicates new total number of that component

PWR20/1-3

used.

Figures
on

the

1-2

inside-rear

supplies
disk

through

cabinet

the

PDP-11/40

system

are

not

ELECTRICAL

Figure
among

1-5
the

characteristics

1.4

KL10-C

3-phase,

percent

listed

each

nominal

value

21.6

KVA

Primary

line

that

Hz.

1-4).

are
The

mounted
power

associated

the

2040

Floppy

Power

System.

SUMMARY

System

the

basic

interconnections

components.

1-2.

Detailed

are

summarized

Input

power

electrical
in

Table

1-3.

with

120

voltage

and

basic

input

must

the

240

Vac,

60/50

Hz,

line

KL10-C

power

within

frequency

Processor

(60

+6,

-12

should

reguires

120

Vac,

Vac).

power

separate

computer

the

KL10-C

from

operation
Primary

compatible

with

the

DECsystem-10

additional

Processor

lighting,

fluctuations.

for

and

part

assembly

Line

approximately
240

(Figure

end

Table

power.

components

showing

operates

than

the

REQUIREMENTS

vary

the

diagram
Power

Processor

5-wire

front

2040

ELECTRICAL

doors

considered

block

are

CHARACTERISTIC

various

requirements

not

Some

1.3

The

1-4.

the

not

power

affected
at

primary

Preparation

information.

PWR20/1-4

conditioning,

outlets

KL10-C

Site

air

should

provided

etc.,

voltage

surges

the

computer

site

must

input

Guide

connector.

Refer

(EK-DEC10-SP-003)

CONSOLE PROCESSOR CABINET

switch paner

1/0 CABINET

CPU CABINET

I/0 COOLING ASSEMBLY

CPU COOLING ASSEMBLY

H7420
No.1

H7420
No.
2

H7420

MA20

COOLING

ASSEMBLY

No.
3
H7420
No.
4

863

H760

POWER
CONTROL

861

POWER

RAW POWER

H7420

SUPPLY

No.
5

CONTROL

EEE:

H7420

S22 |3 ] Hraz0

35;:

H7420

§§$§§H7420

x|zl

No. 1

izl

No. 2

32129 R]|
SRS
|||zl

;;;;;NO.4

IS]
x

TIE[E|T[T|
Nos

nraz0
No

FRONT

Figure

1-2

Front

View

Assembly

VIEW

Power

Supply

Locations

PWR20/1-5

and

Cooling

CPU CABINET

I/0 CABINET

CONSOLE PROCESSOR CABINET

CPU COOLING ASSEMBLY

I/0 COOLING ASSEMBLY

[fi SWITCH PANEL ]

HT7420
No. 1.

H7420

No.
2

COOLING

ASSEMBLY

H7420

No.
3
H7420
No.4

H7420

RAV:WPGOOWER

e e

ngslgR

CONTROL

861
POWER

CONTROL

REAR

VIEW
10-2209%

Power

«©

Assembly

Supply

Locations

View

Rear

1-3

Figure

MA20

and

Cooling

REAR DOOR
CPU CABINET

REAR DOOR
I/0 CABINET

COOLING ASSEMBLY

SERIES PASS
ASSEMBLY

SECOND 64K MA20

(IF USED)

OO = OO

CAPACITOR ASSEMBLY

-S I S

-S I &

H7420

No. 6

8|38 |

p s

nreeo
.

REAR CABINET DOORS

(OPEN)
10-2206

Figure

1-4

CPU

and

I/0O

Cabinet

PWR20/1-7

Rear

Doors

(Open)

DEC POWER CONTROL BUS
1}

-l

_——_——‘———__———_——fl

KL10 C
PROCESSOR

CABINET
FAN

aqu

| PRIMARY ___|
POWER |N

ER
POW
TR

FLOPPY

s%sf'ém

DECWRITER

J&"SR

or| d¢
sc_,lcAapaciT
SSEMBLY

sgglsess
BSS
asD

conTror
=

SUPPLY

H761

KL10-C
ot

H7420

RIPHERAL

)

PDP-11/45

LA36

POWER

SUPPLY

DTE20

863

POWER

CONTROL

=
ac

H7420

POWER

%IMA::o _

SUPPLY

)—1

H7420

AIR FLOW

SENSORS

RH20

POWER
SUPPLY

HTae2

POWER
SUPPLY

H7420

|mazo

POWER

H7420

o
COWER,

7420

mazo

POWER

h———_——_
10-2207

Figure

1-5

KL10-C Power Distribution System Block Diagram
(System

Level)

Table 1-2

KL10-C System Power Requirements

Parameter
Voltage:

Value
KL10-CA

110/208 Vac

KL10-CB

240/416 Vac

Input Connections:

3-phase, 5-wire

Current:

60A/phase (maximum — 60 Hz operation)

30A/phase (maximum — 50 Hz operation)
Input Frequency:

KL10-CA-60Hz+ 1 Hz
KL10-CB-50Hz+ ] Hz

Input Power:

21.6 KW

Cooling:

Forced Air

PWR20/1-9

Table 1-3
Electrical Characteristics Summary

Qty

Assembly

863* Power Control

DEC Type No.
863

Electrical Characteristics
Input Requirements (Max)

Voltage

90-132/180-264 Vac

Phase

3-phase, 5-wire

Frequency

47—-63 Hz

Current

75A/phase (CB)

Includes:
1

Power Distribution

Panel
1
|

Pilot Control Board
Auxiliary Power

w7000

Supply Board
1

AC Low Voltage

W516

Detector Board
1

Power Control

G8015

Output Power

Logic Board

Outlets**

Ten (8 Switched, 2
unswitched)

Indicator Driver

G8017

Control Element

Board

g K1

30A

(Relay or

CB3

15A

Circuit Breaker)

CB4

15A

Switched fi

CBs

15A

CB6

1SA

CB7

15A

CB8

1S5A

\. CB9

1SA

Unswitched { CB2

30A

CB10

861 Power Control

861-D

Input Requirements (Max)

861-E

Voltage

861-D: 90-135 Vac
861-E:

Includes:
Pilot Control Board

5411522

180—270 Vac

Phase

861-D: Three

Frequency

47-63 Hz

861-E:

15A

Current

861-D: 24A/pole
861-E:

Circuit Breaker

Three

16A/pole

861-D: 30A/20A
861-E: 20A

(CB1)
*Two models:

863D (120 Vac. 60 Hz) and 863E (240 Vac, 50 Hz)

**Same outlets have duplex connectors

PWR20/1-10

Table 1-3 (Cont)
Electrical Characteristics Summary
Qty

Assembly

DEC Type No.

Electrical Characteristics

Power Requirements
Full Load

861-D: 2870 VA
861-E: 3830 VA

No Load

861-D:

10VA

861-E:

10VA

Output Power

Outlets

Six duplex (4 switched,

Outlet Current

861-D:

2 unswitched)

12A/outlet,

16A/branch,
24A total Power

Control
861-E:

12A/outlet,
16A total Power

Control
7

H7420 Power Supply

H7420-A

Input Requirements (Max)

H7420-B

Voltage

H7420A:

Phase

H7420A: Single
.

Frequency

Includes:
1

Power Control Board

5411086

120 Vac

H7420B: 240 Vac
H7420B:

Single

47—-63 Hz

Current

Circuit Breaker

Power Requirements

Full Load

No Load

Output Voltage

t8V@I1A
+1SV*15V@3A

Seven separate regulator
outputs, 20—30 Vac

(25Vact 20 @

each; single 115 Vac
convenience outlet

Clock

0—5 V square wave at
47-63 Hz

PWR20/1-11

Table 1-3 (Cont)

Electric;ll Characteristics Summary

Qty

Assembly

H744 Regulator

Electrical Characteristics

DEC Type No.
H744

Input Requirements (Max)
Voltage

20-30 Vac

Phase
Frequency

Single
47—-63 Hz

Current

12A

Fuse (F1)

15A

Output Power

Voltage

5Vdc £ 60 mV

Current

25A

150 mV p-p (max)

Ripple

H745 Regulator

H745

Input Requirements (Max)
Voltage

+15Vdet

20-30 Vac

Phase

Single

Frequency

47—-63 Hz

Current

+15Vdc@

20-30 Vac @

15A

Fuse (F1)
Output Power

Voltage
Current

Ripple

H754 Regulator

H754

-15 Vdc £ 50 mV
10A

450 mV p-p (max)

Input Requirements (Max)
Voltage

20-30 Vac

Phase
Frequency

Single
47—-63 Hz

Current

Fuse (F1)

10A

Output Power

Voltage

+20 Vdc £ 5%
-5Vdc * 5%

Current

8A @ +20 Vdc
1A @-5Vdc

H770 Regulator

H770

Input Requirements (Max)
Voltage

20-30 Vac

Phase

Frequency

Single
47-63 Hz

Current

12A

Fuse (F1)

15A

Output Power

Voltage
Current

PWR20/1-12

+15V +3%
0—10A

The

KL10-C

building

cabinet

ground point.

is provided

ENGINEERING

Table

1-4

Power

point

Complete

should

cabinet

connected

grounding

the

information

in the Field Maintenance Print Set.

1.5

diagrams

grounding

lists

DRAWINGS

reference

contained

Distribution

schematics

and

wiring

the

Field

Maintenance

System

units

within

configurations.

PWR20/1-13

the

interconnection

Print
2040

Set

system

for

the

Table 1-4

Reference Drawings
Title

DEC Dwg. No.

No. of Sheets

863 Power Control, Detailed Schematic

D-CS-863-0-1

Auxiliary Power Supply (W7000), Detailed

D-CS-W7000-0-1

D-CS-W516-0-1

D-CS-G8017-0-1

D-CS-G8015-0-1

H7420 Power Supply, Detailed Schematic

D-CS-H7420-0-1

H7420 Power Control Board

C-CS-5411086-0-1

H744 Regulator (+5 Vdc). Detailed

D-CS-H744-0-1

D-CS-H745-0-1

D-CS-H754-0-1

Switch Panel, Assembly Drawing

E-AD-7011639-0-0

Capacitor Assembly, Detailed Schematic

D-CS-7009878-0-1

+10 V Reference, Detailed Schematic

D-CS-G8013-0-1

-5.2 Vdc Control, Detailed Schematic

D-CS-G8010-0-1

-2.0 Vdc Control, Detailed Schematic

D-CS-G8011-0-1

-5.2 Vdc Heat Sink, Detailed Schematic

D-CS-7009405-0-1

-2.0 Vdc Heat Sink, Detailed Schematic

D-CS-7008404-0-1

DC Low Voltage Detector, Detailed

D-CS-G8014-0-1

Schematic
AC Low Voltage Detector (W516), Detailed

Schematic
Indicator Driver (G8017), Detailed
Schematic
Power Control Logic (G8015),
Detailed Schematic

Schematic
H745 Regulator (-15 Vdc), Detailed

Schematic
H754 Regulator (+20, -5 Vdc), Detailed

Schematic

Schematic
H761 Power Diagram

;
D-IC-KL10-0-1

PWR20/1-14

Table 1-4 (Cont)

Reference Drawings

Title
H761 Detailed Interconnection Wiring

DEC Dwg. No.

D-IC-H761-0-

Diagrams (H761-0-1 through H761-0-8)
H770 Regulator (+15 Vdc), Detailed

D-CS-5411207-0-1

Schematic

PWR20/1-15

No. of Sheets
9

CHAPTER

INTERFACE

2.1
An

LEVEL

BLOCK

DIAGRAM

Interface

system

Level

shown

application

Power

DESCRIPTION

the

its

power

the

Supplies

this

Cabinet.

The

these

this

The

and

KL10-C

863-D

Power

entire

power

and

Power

the

Floppy

861

Power

from

the

863.

The

861

Cabinet.

The

H7420

identical

power

supplies

and

Disk

system

considered
regulators

part
are

are

not

Disk

Control,

those

also

controls

the

regulators

2040

discussed

which

Power

internal

the

controls

system.

the

CPU

Distribution

Control

are

Floppy

not

the

DECwriter,

the

cabinet

The

the

additional

supplies

I/0
powering

those

Power

System;

further

manual.

Switch

Control.

off

input

fans

are

2-1.

controlled

primary

PDP-11/40

devices

power

further

diagram

Figure

PDP-11/40,

receives

the

block

in
ac

ANALYSIS

Panel

During

means

separate

switch

power

for

furnished

Capacitor
Series

normal

ECL

Assembly

Pass

the

eénergy
The

under

the

ferroresonant

Assembly.

the

switch

power

logic

for

same

operation,

POWER

removes

the

located

cabinet

system

the

storage,

ferroresonant

PWR20/2-1

863

turned

Switch

Panel.

emergency

Raw

the

Central

H760

and

conditions.

Processing

Power

Unit

Supply,
H761

transformer

(CPU)

Regulated
primaries

DEC POWER CONTROL BUS
e

POWER REQUEST (L)

120/240Vac

120/240vac

-1y |CAPACITOR| -11

ASSEMBLY

60/50Hz

CONTROL pL20/240Vac

|
l

|—

DTE20

H745 REG.

|+AIR FLOW SENSORS

H744 REG.

DIA20/

DMA20

H744 REG.

17420 P.S.

120/7240Vvac

H744 REG.

H744 REG
H744 REG

H744 REG

120/7240Vac

H7420 P.S. | H7420 PS. +20
|—
H754 REG. | H754 REG.
H754 REG | H754 REG.

n754 REG. | H754 REG 12Ol MA20

H744 REG. | H744 REG. +:

SECOND MAZO|

H754

2-1

—

l }_L44_RE_G.+)1_44_REG _{--5—-!

e |
4
REG | H744RE
L174

KL10-C Power Distribution System Block Diagram
(Interface

Level)

PWR20/2=-2

REG

———

L GEEEEEy U G G SR e%B M ] IS SEEMEEES G I G SRR L& B ]

Figure

| H754 REG | HTS4 REG =5 ma20 |
—— ——

H744 REG | H744 REG.

H754

RH20 o |

l
|

n744 REG

H770 REG.

H744 REG.

H7420 PS.

POWER

H744 REG.

863

——|

H7420 PS.
H744 REG.

POWER

| POP-11/40

+15

PRIMARY I
3 PHasE

_
ALS
PERlP'H'ER

K‘é'POU- ¢

H761
PASS
SERIES

DECWRITER

ASSEMBLY

7009878

SUPPLY

LA36

120/240Vac

Flé?g:Y

SYSTEM

120/240Vac
H760
POWER

PROCESSOR

120/240Vac

CONTROL

120/240vac

KL10-C

FaN

—=

Pg\?ER

| SIDE UNITS

GND

SIDE UNITS |

~ | T0 RIGHT

EMERG. SHUTDOWN (L)

To LerFT | ¥

are
a

wired

full-wave

supply

are

ocutputs

+10%,

overall

the

power

-2.0

and

LEDs

the

correctly,

other

being

Each

off.

voltage
are

Both
CPU

open

are

+15

line

and

-15

tolerances

the

capable

wired

ferroresonant

The

With

are

energy

these

pass

amperes

the

although

for

regulator
circuit

card

generate

ail

%1%

levels

The

output

regulator.

control

cards

voltage

are

breakers,

the

are

performed

cards

protection,

cards,

voltage

each

consists

not

control

transistor.

output

regulation,

regulators

common

regulator

tripped

voltage

three

regulators

(G8010

present.

not
is

functioning

the

LEDs

identical

all

cards

used.

POWER
from

WARNING

the

(SIGNAL

capacitor

overvoltage

are

Regulation

indicate

that

the

assemblies

between

H761

regulator

regulators,

sink

series

the

than

1is

portion

sensing.

indication

voltage.

outputs

level

only

the

input

H761,

current

The

supply

heat

and

used

the

maximum

are

Within

G8011)

Y15

=-2.0

with

and

the

The

regulator

back

outputs

major

linear

outputs

removed.

the

remote

the

The

winding.

power

while

nominal

limiting.

sequencing

tolerance

point

490

common

breakers,
and

delta,

star.

120/240

the

current

provides

well

-5.2

when

circuit

added,

H761

and

-11

-30%

hold-up

3-phase

assembly

The

and

863

Power

RETURN)

CROBAR

line

Control.

pairs

These

shorted,

PWR20/2-3

are

line

connected

pairs

depending

the

are

simply

the

state

the relay contacts associated with the individual control
Before power is applied to the system,

relays.

both sets of

contacts are closed. Apprdximately 5 seconds after power is
applied,

both sets of contacts are opened, with CROBAR lagging

POWER WARNING by

5 milliseconds.

During power

shut-down,

CROBAR again lags POWER WARNING by 5 milliseconds.
13

At least

seconds must elapse between power-down and the next
sequence.

power-up

The power supplies and regulators in the I/0 Cabinet are

similar to those in the CPU Cabinet.

Type H770 and H745

regulators are added to the I/O Cabinet.

The H770 has been

designed for a higher degree of regulation than provided for
by the power control board in the H7420.

The +15 Vdc for the

air flow sensors is furnished by the H770.
-15

Vdc

the

DIA/DMA20

The H745 supplies

logic.

The CROBAR that is applied to the CPU is also applied to the

H770.

In this case,

seconds will

elapse

the CROBAR assures that approximately 5
so

that the

cabinet

fans

can get up to

speed before power is applied to the air flow sensors,

thus

avoiding accidentally initiating an Emergency Power Off
sequence.

As shown in Figure

2-1,

the DEC Power Control Bus

to both the 863 and the 861
is provided in the 863

Power Controls.

connected

An override switch

for maintenance purposes.

This switch

overrides a fault condition so that the processor can be
powered-up

for

troubleshooting.
2

2.2
Two

BASIC
types

KL10-C:

The

OPERATION

power

switched

main

input

must

primary

the

(wye-connected).

the

closed,

various

circuits

breaker.

Closing

the

unswitched

The

circuits

Supply,

Driver

with

These
the

863

apply

this

POWER

WARNING

power

primary

are

the

863

system

and

two

Vac

the

(that
the

circuit

breakers

are

applied

the

Vac

Control.

Auxiliary

G8011

Power

Indicator

Control

active)

necessary

Logic.

long

the

Approximately

opened,

is,

POWER
in

power

individual

Power

normally-closed

are

120/240

861

remain

applied

closed.

contactors

the

G8015

Panel.

breakers

W7000

(and

circuit

rest

circuit

applies
the

Vac,

additional

Power

individual

one

and

logic

switched

the

power.

breaker

power

863

Closing

circuit
Vac

primary

240/416

Detector,

Switch

analysis

and

include

active

the

and

outlets

system,

main

breaker

closed,

circuits).

120/240

863,

breaker

the

lines

relay

the

Vac

120/240

Voltage

the

switch

from

the

indicators,

switch

other

Low

circuit

power

after

When

unswitched

120/208

circuit

the

circuits

and

the

fault

POWER

inhibit

inside

and

unswitched

inside

main

convenience

W516

four

considered

power

863

3-phase
863

the

PWR20/2-5

switch
As

applied

863

front

closed,

system,

clock,

863.

shown

the

memory,
energizes

result,

panel.

primary

and

the

also
a

seconds

CROBAR

removing

the
ON

series

When

these

power

Figure

1is

2-1.

The

application

three
each

primary

orange-colored
of

the

three

power

lamps

phases.

the

When

the

863

the

863

front

POWER

indicated

panel,

one

switch

for
the

Switch Panel is closed, the red LED (POWER) next to the
switch

lights,

system.

the

indicating

Fault

indicators

Power

Control

fault

conditions

indicator

seconds.

identified
863

2.3

The

Power

the

are

Switch

fault

the

and

single

will

These

LEDs

EIGHT

Overtemperature

(unused)

(6)

Circuit

breaker

(8)

Cooling

Assembly

The

the

(four

CPU

both
one

the

system

down

863

several

FAULT

will

for

particular,

front

power

panel

least
are

the

are:

locations)

power

open

switched

(two

tripped

locations)

PANEL

Panel

Processor

Switch

flow

door

any

conditions

(5)

Switch

air

with

remain

orange-colored

lights.

Insufficient

SWITCH

conditions,

individually
Control.

Panel.

Panel

power—-down

Eight

associated

Switch

prevails,

application

(4)

Console

the

and

the

automatically

(LEDs)

the

i1s

located

Cabinet.

the

Figure

front
2-2

Panel.

PWR20/2-6

top

shows

area
a

front

the
view

FAULT

r
!

LOAD

SW/REG

DIsSK

POWER

FLOPPY

ENABLE

POWER ON

EMERGENCY

POWER OFF

DISABLE

10-2237

Figure

2-2

Front

View

PWR20/2-7

Switch

Panel

The

Switch

Panel main

application

and

removal

system

the

POWER

ON-OFF

red

LED

POWER

indicator.

means

associated

Emergency

are:

Normal

the
2.

functions

shutdown;

with

the

manual

Red

system

FAULT

indicator

(8)

possible

power

distribution.

BOOTSTRAP

PDP-11/40

front

enables

power

POWER

fault

from

panel

(LED)

for

conditions

disk,

Floppy

(SWitch

disables

switch

OFF

mechanical-reset-only

eight

switch

EMERGENCY

with

switch

feature.
any

one

disk

the

bootstrap

or
A

separate

function.

2.3.1
The
in

Switch
Figure

between
LED

System

Connections

Panel
2-3.

the

lights

Vdc

LED

when

system

power

FAULT

example,
no

LED
in

air

lights

the

case

the

source

Control

as,

Power

The

tripping

interfaced

863

switch.
for

and
is

overall

input

the

Switch

applied

when

series

flow.

PWR20/2-8

line

system
1is

the

power-related
pass

shown

connected

Panel.

through

The

POWER

fault

circuit

occurs,

breaker

fee3— — — T~ ]
POWER

CONTROL

FAULT (M) —Dow-l‘i}—z(€ Js"l

' PWR REQ (H)—

lo-ovsamoe (H)

|
|

+8V

)

conTROL BEa

Ji3-3 1J5.2!

€ |

_J13-1J\< J5-4!

(863)

SWITCH PANEL

Jor-3 st
<

J7-2 <.:4-2!

Jur-1

POWER LED

poweR

OFF

o
ST

SWe

-éqsqi'
J3-2

SwWS

B0OTSTRAP

POWER ON

SwW2 _- DISK

——

SW3_

CLE P

— e

—

frorti/a0 — 71

lJl-Z\:.H-Z'

FLOPPY Lul-3eeJi-3
PCLEN
Z

enaBLE ot Jn-el
—

DISABLE

Al S

SWI__~
SW REG !qtlsaa14 -

L 433

sa-3)

(_1'*

FAULT LED

)

BOARD

BM873

fraggoral

asgas| ||

=J2~2;

—— — —

‘Jz_,\}ro DTE20
7

ee
10-2232

Figure

2-3

Switch

Panel,

External

PWR20/2-9

Connections

2.3.2

Operation

Power

applied

actuated.

The

the

cabinet

fans

maintenance

863

Power

(at

should

problem

System when
POWER

should

some

and

the

override

actuated,

the

POWER

POWER ON

type

switch

light

and

switch

indicator

the

blinks

rate).

Switch

Panel

program

panel,

the

loaded by

actuating

momentary

switches.

For

loaded manually

following

Set

the

steps

are

PDP-11/40

settings

for

the

switches
bootstrap

Actuate

the

ENABLE

switch;

Actuate

the

switch

depress

and

hold

When

the

load

REG
it

has

the

appropriate
if

the

bootstrap

PDP-11/40

front

performed:

console

the

example,

through

the

indicator

audible.

exists

A bootstrap program

2040

associated

Control

the

desired

program.

depress
on

the

and

2040

hold

Switch

in.

Panel;

in.

started,

release

both

2040

Switch

Panel switches.

outside
power-

below

limit

necessary

operate

Panel.

Vac

for

Hz,

started.

'—l

power,

Switch

2040

not

PROTECTION

drops

power

230

'.l

Whenever

the

O
M

POWER-FAILURE

)

2.4

controls

other

any

running,

program

0
c

the

Once

PWR20/2-10

115

(190

Vac

as measured by

for

The

KL10

asserts

signal

CPU
POWER

into

interrupt

and

clearing

Coincident
end

(under

and

same
and

save

power

location

all

machine

start-up

back

into

its

APR

the

CPU

and

the

reads

Power

863

the

Line

power-fail

orderly

the

power

failure.

state

and

Refer

the

KL10

shutdown,

CPU

process.

above
the

power

POWER

control

WARNING

Flag.

This

sequence

and

storing

for

includes

APR

allows

information

CPU,

The

KL10

CPU

registers),

processor
routine

entire

KL-based

information.

PWR20/2~-11

traps

has

restore
The

during
to

its

the
prior

function.

System

for

the

PDP-11/40

20-microcode

lost

restored

failure.

totally

(EK-KL10-TD-002)

fail.

the

ready

traps

(data

power

then

Processor

address)

the

Central

PDP-11/40

that

the

(at

power

again

Introduction

program

reading

1is

automatically

power

KL10

manual

PDP-11/40

the

prior

process

information

the

executes

system

The

power-fail

volatile

state

shutdown

conditions)

restored,

routine

Description

CONI

peripherals

and

the

drop

memory.

condition

When

KL10

shutdown

power

setting

the

begin

with

the

location

30,

begins

KL10

the

WARNING.

bit

the

front

senses

Technical
detailed

AUTOMATIC RESTART

2.5
The

only

automatic

restart

feature

present

the

KL10-C

with £he ac. During a powér-failure, for example, if the ac
comes

back

up,

restarts.

The

minimum of

power

for

Only

faults

unrestartable;

they
to

failure

cannot,

(one

period

are

Introduction

manual

power

seconds

this

back

the

however,

shot

KL-based

(EK-KL10-TD-002)

for

come

timer

automatically
back

disallows

for

power

coming

time).

restartable.
must

program

All

dealt

with

System
more

other

manually.

Technical

detailed

PWR20/2-12

faults

are
Refer

Description

information.

CHAPTER
UNIT

3.1

This
major

LEVEL

DESCRIPTION

INTRODUCTION

section

describes,

assembly

diagram

the

KL10-C

introduces

the

chapter.

identified

and

all

Then,

major

each

paragraphs.

simplified

schematics

Maintenance

Set

Power

the

System.

all

assembly

the

System

major

descriptions

and

diagrams.

for

detailed

PWR20/3-1

are

schematic

each
block

(Figure

assemblies

further

Refer

detailed

interconnections

component

The

operation

Distribution

Here,

assembly

subsequent

detail,

2040

the

are

3-1)
are

shown.

described

supported

the

Field

diagrams.

DEC POWER CONTROL BUS
3

r—

OVERRIDE
o—r

_.-.

ASSEMBLY

SENSORS
RS

HT7420

| 120/240vac_60/50Hz

120/240a0ac
60/50H2
3-PHASE
5-WiRE

CABNET

[Amviow

+15V FROM H770

No. 3

, CROBAR

|| 120/240Vac 60/50Hz

HT420

120/240Vac_60/50Hz

H7420
6

m—"

No. 1

20-30Vvac
1
HT70

+15

} 3-PHASE 4-WIRE

-5

r H744

MAZ0

|
I

AC TO FANS
CAPACITOR|

H761

-52

Y REGULATEDL _20]
ASSEMBLY

cPu

20-30Vac

+zo
+zo H754
+2o H754
No. 4 H754

I| 120/240Voc_60/50Hz

| 120/240vac_60/50Hz

H7420

FLOW
AIR
SENSORS

AT
H770

CPU CABINET

H760

CROBAR

NS IS GEE B ] L A ] & /]

_{\ Foower |-11Y { Assempry
7009878

POWER WARNING

H744
-5

SUPPLY

4 CB TRIPPED

R"‘Z

H7420
+20 +2o
+20 [H754
No. 7 | [H7sa|

+15

)

r—'j
DIAZO DMA20

H744

[H754 H754
+zo
+20
1420,t5

ASSEMBLY

120/240vVac 60/50Hz

20-30Voc

- +5

+5 +5

H744 | | H744

COOLING

SWITCH

15,215

H744 H744 H744

CABINET

DOOR

-15

-5

IS G SR -

H745

] | H744
H744
H744 ul
‘m
H7420
+5
+5
+5
No.2

DOOR

T20- 30Vec
20-30Vvac

| 120/240vac 60/50Hz

internal to those devices and aore not
Power Sysmzl
port of the 2040__
considered

+2o

No.

|
o

1/0 CABINET |

20-30Voc

PRIMARY

ASSEMBLY

AIR FLOW SENSORS

863 ] 120/240vac 60/50Hz
| POWER |‘ c%%VTVggL
|

POWER

r—____———__—_—

120/240Vac_60/50Hz_3-PHASE 5 WIRE

CONSOLE PROCESSOR CABlNE|

120/240Vac

l—= UNSWITCHED CONVENIENCE OUTLETS

H744

H7420 —sa1 [7sa 754 H.,“ (—L—]H_,“
No.5

+20

[20-30vac

+20

MA20

+zo

10-2209

Figure 3-1

KL10-C Power Distribution System Block Diagram
(Unit

Level)

PWR20/3-2

3.2

863

The

863

entire

POWER

Power
power

available:
A

single

Control
system.

863-D

Block

diagram

and

Two

Major

Diagram

the

863

pilot

detector;

power

control

indicators

(LEDs)

override

prevents

the

When

the

panel

1is

Auxiliary

the

power

the

power

863-E

(relative

back

power

control

(240
both

Vac,

the

are

Hz).

controls)

Supply

also

made

power

indicate

for

863.

The

the

Switch

Control

and

the

outlets
the

power

circuit

respectively.

PWR20/3-3

fault

driveYts.

purposes.
fault

the

when

OVERRIDE

indicator

isolation.

indicators

LED,

the

phase

follows:

distribution

directly

(convenience

presence

red

indicator

summarized

W516

toc

two

panel

Panel.

the

Figure

low-voltage

eight

during

other

applied

available

maintenance
down

low-voltage

flip-flop

the

power

ac/dc

bank

for

shown

distribution

usage;

indicator

breaker

blinking

One

power

powering

Power

circuit

and

associated

located

Power

lamps

logic

from

863

board;

provided

Control

internal

provides

actuated,

unswitched

Three

the

and

include:

for

enabled.

the

main

machine

indicator

Operation

circuit

override

POWER

with

oscillator

located

Hz)

Power

control

supply

Analysis

subassemblies

associated

description

power

versions

Vac,

auxiliary

application

below.

3.2.1

3-2.

controls

(120

detailed

provided

block

CONTROL

Low

the

Voltage

breakers

outlets
A,

Detector.

that

and
and

W7000

the
C

feed

861).

power,

UNSWITCHED

SWITCHED

OUTLETS

POWER

—»

pCc—>
N——]
28—

GND

POWER

I
-

POWER
CONTROL

VOLTAGE |AC LOW
LOWDETECTOR

LOGIC

(W516)

CONTROL

(GBO15)

SUPPLY
(W7000)

POWER

’-

- WARNING

CROBAR

—» +5

AUXILIARY

RIPPED

KT BKR

A, 8C.D

OVERRIDE
DA

Dlsrmafinon
PANEL

AIRFLOW

POWER

DOOR OPEN

OVERTEMP

> -15
POWER UP

FAULT AND
POWER ON

INDICATORS

POWER REQUEST

P-€£/0z9Md

POWER

POWER REQ
BOARD

POWER

DOWN

EMERG SHUTDOWN |

PILOT CONTROL

~ GND

———

DOWN

—

sSwiTcH
PANEL

[

|
——

FAULT AND

CONTROL

INDICATORS

INDICATOR

POWER

DEC POWER
BUS

DRIVER

[

AIRFLOW A —MEM2)1 (gso17)
(MEM1)

AIRFLOW B —————

——a

alRFLOW ¢ —/)]
aIRFLOW p—CPUL
NOT USED+ OVERTEMP —————

| 3 ,)
[4,
S-IN

DOOR OPEN ————

__-

OVERRIDE

CKT BKR TRIPPED

‘

——

INDICATOR

8
—o

OVERRIDE
10 - 2194

Figure

3-2

863

Power

Control,

Block

Diagram

Before the dc butputs of the auxiliary power supply reach
rated

value

(+5,

+15,

-15

V),

POWER

signal

from

that

supply resets a fault flip;flop in the G8015 power control
logic.

The

POWER

flip-flops
When
the

the
863

signal

(indicator

auxiliary
Power

Closing

the

control

relay

storage)

power

Control

POWER
and

also

resets
in

supply

ready

switch

the

five

G8017

voltages

fault

Indicator

reach

rated

Drive.
value,

for

operation.

the

Switch

Panel

energizes

Pilot

Control

contactors

the

Board.

As a result, 3-phase ac is.applied to a series of circuit
breakers

thg

power

distribution

outlets).

These

circuit

the

power

controls

and

supplies

seconds

after

power

other

Approximately

normally-closed
Control

Logic

CROBAR

are

breakers

panel

and

opened.

POWER
The

(switched

control

primary

the

KL10-C

power

Processor.

on,

the

ready

for

lines
now

KL10-C

turned

WARNING

power

Power

operation.

The

the

Low

3-phase

prescribed
60

Voltage

the

voltage

input

limits

system).

limit,

Detector

(e.g.,

the

machine

drops

below

down

sequence.

fault

sensors

accidentally

continually

ensure

greater

line

power

actuated

opened).

sequence
if

CROBAR

PWR20/3-5

volts

and

for

above

However,
the

also
a

the

voltage

remains

limit,

(e.g.,

Both

normally.

preset

down

line

than

voltage

functions
the

the

senses

863

POWER

120

the

1if

Vac,

preset

the

line
a

one

cabinet

WARNING

wvalue

within

executes

occurs

cooling

peak

power

door

signals

the
is
are

sent

(relay

the

KL10-C

contacts

removed

Timing

from

normal

operating

under

1is

863

Power

the

Switch

When

closed,

Panel

activated.

long
A,

one

at
a

eight

Assembly;

these

OVERRIDE).

Detailed
3-3

Control.

Refer

Maintenance

time

main

power

Circuit

OFF

the

when

the

switch

immediately

associated

switch

OVERRIDE

The

the

diode

remains

exists:

Switch

the

POWER

Switch

illuminated

airflow

circult

breaker

(A);

door

open

diagram

and

the

until

LED

the

Switch

condition,

other

and

with

activated

conditions

open

tripped

sensors
in

(B);

the

(one

Description

simplified
also

condition,

door

are

remains

rate.

fault

POWER

least

powering

conditions

light-emitting

LED

and

outlets.

POWER

During

that

down

power

Panel

overtemperature;

Pass

Figure

This

FAULT

H761

3.2.2

the

POWER

opened.

specifies

the

blinks

then

switched

Panel

EMERGENCY

the

Control.

indicator

the

activated,

only

ensures

shutting

indicators

switch

which

between

Two

during

condition

system.

detected.

removed

powered-down

elapse

either

Panel

closed)

logic

system,

Switch

indicate

Control

will

Power

seconds

fault

are

the

CPU

schematic

drawing

D-CS-863-0-1

Set.

PWR20/3-6

the
the

863
Field

Power

"SWITCHED

UNSWITCHED

POWER OUTLETS
J23
J31

CB1
75A

—

[

“rT T T "

GND

¥
2

OPERATION

S47K ;» 47K :»47'(

P
T T T TT

b
T T T T T T '( ————— B

¢B

——

a|we

J-

' KZI

120V

cese

2q0v]

colL
=

}

b
coiL

[ K3

120vac ~ $R1 3R2 LR3

;

P/ J11

pial et it

C8s

JUMPERS

OUTLETS

J28

———

Jaz7

FILTER

J2e

SWITCHED

cB2

—1LOW PASS —-°:=*

Bc |

J2s

POWER OUTLET

R
Oa

POWER

as]Gy 640
1] Jd 6461
1§ TodBeod64 ool64|
J24

1"
:

|
|

fiu3CML

N
1
'_

(ALTERNATE CONNECTION

FOR

3]4

240V OPERATION)

GRS

GEES

PILOT CONTROL]

240V

-3t

24V, CONTROL

RELAY

LOCAL | REMOTE

OFF

EMER SHUTDOWN

GROUND

I 2

LHUNITS)

J10
{2

POWER

REQ

J2
o2

J3
I o2

J7, REQUEST
gI
(L)
2

213
Gb

o——¢

EMERGENCY

Power

J
-

(L)

GROUND _

[ DEC_
%
POWER EMERG SHUTDOWN

eTRL
BUS

POWER

I T]_REQUEST (L)

3 ¥

SWITCH PANEL—]
I
I PO

PWR

* DEC
EMERG SHUTDOWN _ poweR | TO

ceounD

POWER REQ (L) »BUS
CTRL [ RH UNITS

- 71958

Figure

3-3

863

Power

Control

(Sheet

Simplified
1

PWR20/3-7

Functional

Schematic

AUXILIARY

FROM

POWER SUPPLY
w700

S————
e,

240V

o1e

120V
.....
:

r———————
AC LOW VOLTAGE DETECTOR

(W516)

D18

’
L

I E1

urenes!

———————
— ———

¥ os

SIS

GRS

—

— —
|

—" e
G

CERE

SIS

]

LSS

LOW

I
|

SESTEES

GRS

OFF

OVERRIDE

— —

y
S

{

DETECTOR

‘

PEAK |9]

+5v

R9 I

-15y

T‘

I R26

L
L

ONE¥

RI3

LEVEL (L)

A2|

—
¢t
82

—

REF SHIFT

019

VOLTAGE

+15y

COMPARATOR

c1e

RIO

OVERRIDE

SEEN

SRS

(L)

X OVERRIDE (L)
|

O
?

2N3790

+5v

———————

AUXILIARY

|P|_4

u’

p,’d,s

1’1E

120VE"/ 12 :‘

PY}

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t ;3

Jaov

J
l

—

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\[\

15VvAC

RTN 4

—*

158
o

}

:
l

L 25A

I +SV

+30V

wmz

30vac | 5 l
e

aovac | 3

POWER SUPPLY

I(W”OOO)

-t _L GDOZI

;

gy '

1
i

SNl

— N\

+30v

# V :
|

s
1

_ ~

‘

| |
||

+ 12V

4+ l

— |

.
}?

lrusv

[ |

s 1

J:-

R2Y Tcsl

i'“

' %Rw

Figure 3-3 863 Power
Control Simplified

Schematic

Functional

(Sheet

PWR20/3-8

—12v

(1Y 4

;‘r\czz

€3

]

—

;

INT

+15V
+5y

18V

’

£4

{v#r:ifi

+®
I

L_____________________________]

10 - 1998

[1 Iz[s[cfl

112]314]5[6]7]8] 9[10111[1fl

TITIIITITITT
—-—b——_-_

—-_——_—_—

___-—_———

AIRFLOW A (L)

1 rr—mTTt—
——

AIRFLOW € (L)

OVERTEMP (L)

FAULT

LOW (H)

POWER

—

FAULT (H)

OPEN B (L)

5ms

A (L)

c{>

AIRFLOW 8(L) —s

AIRFLOW C (L)

R oTM

AIRFLOW

D (L)

_as

OVERTEMP (L)

—CaR O

CKT BKR (L)

1
| power urp (L)

DOOR OPEN (L)

! POWER REQUEST
(L)

INDICATOR

2|2

+—

f\//
N

‘

WARNING RTN ,

+5V

(o)

4F NC

R RTN

R O

EMERG SHUTDOWN

LNC

GROUND

r-SWITCH

+5v—v4 4

lPANEL

)

FauLT (L

gg:gn ON |

OVERRIDE (L)

—

GATE

POWER ON

\-///

1'
10 - 2196

—_—————

Figure

3-3

Control

863

(Sheet

Power

Simplified

Functional

Schematic

PWR20/3-9

—
-

CROBAR

r— 818

CROBAR (L)

‘I”]__";“

POWER

"
BLINKER

# 7

m//

POWER

WARNING (L)

sls
e

GATE

Sms

~Va

RESET GATE
hhz OSCILLATOR

! ——@—l

VA~

R OF—ww

+5v

+5V

warning

3ms

L—

LOGIC

[

J20fP20 | Pry2

R Ol

LATCH

CRgEAR

PWR REQUEST (M)

DRIVER

POWER UP

INDICATOR

_I=—

._Do_\,

1w‘
INDICATOR

PWR REQUEST (L)

POWER UP

GATE

FAULT
RESET GATE

13sec

CONTROL

UP-DOWN

ONE SHOT

,—Q_/

__—1

POWER

POWER UP (L)

AIRFLOW

DOOR OPEN A (L)

VERRIDE (L)

CKT BKR (L)
DOOR

_—_——————

AIRFLOW D (L)

STORAGE

_————_——_

OVERRIDE (L)

AIRFLOW B (L)

863
POWER

HT76

CONTROL

H76!1

RAW POWER SUPPLY

1
1

SERIES

-2y
-

-12v

1VRTN

PASS ASSEMBLY

524)

CAPACITOR
e mBLy |12V
RTN

8|
—

—

1 ono

4
—

|
0

€|

el
=

B
.

(5)

220vac
{2) CPU CAB
FLUSHING FANS

|}
L

FANS

120VAC 0.SAEA

-20A

cPu

|—
<

o}
]

-2

[—— [CPU

COOLING

3
—

LT“

B0
-

—
J2

—y

"—t‘

NEMA

—

|6|

L21-20

NEUTRAL
(N)

COOLING ASSY

—

)

7:
{4)

ps—

8 |

h——d

R-

B
—
3

10
L

POWER CONTROL

jess

IS LAy

PWR

REQ (L)

5]| EMRG SHOWN

3
H—{

I
SN g P
2

GND

FANS

220VAC 1.5A

3
9

GROUND

— 6ND

(2T

—
J2
2]

—{ NEUTRALTM

—

| ASSEMBLY

CAB FAN
{1

ror-11/40

La3e

— L DECWRITER

2 .

[~ ]

[J6 ]

11-

— L JPERIPHERALS|

W-\—

. .

ey
K

—

2
3
E—

OVERTEMP

CIRCUIT

L@I

BREAKER

TRIPPED

CPU CABINET AIR FLOW SENSORS

12 ]

170 CABINET AIR FLOW SENSORS

bfiqTIEWq;|b¢qT|B< -

+ <= [+1<]=] [+]<]-) [+]<]-]

1
i

[2 |

DOOR SWITCHES

CPU CABINET

—

1/0 CABINET

J1-6

TO H770
.

GND

J-5

||
6|

+15v

CPU

CT4
~\ CROBAR

CT3

s [ [caoaAR RTN
|

{] Pwr warN

—1

POWER WARN

oND

cT2

ol U POWER WARN RET

CABINET

BACKPLANE (CPU #1)

‘*———-—————f: CROBAR

cn{: GND

J1-2 ¢

ANIES]

TO H770
10-2197

Figure

3-3

863

Power

Control

(Sheet

Simplified

PWR20/3-10

Functional

Schematic

863
POWER CONTROL

MARGIN CHECK

T1INST

PWR ON

INST PWR

JINS

+5V

|LFAULT

—{

powER

EMERGENCY

POWER

‘) 863

J13
=

[

J3 _1

Frow

PANEL

POWER ON

RTN

J7
1

;. 2

OFF

4
;
ON

SWITCH

PANEL

2
3

POWER SUPPLY
J2a

M7420

OTE 20

NO.2

fij

J2-5

—

12-6
.s

V102

J1-5

H744

GND J1-3

GND

e
+5

GND

J1 - 2 p——————

PTE - U

1-5b———o

J1 5

onp VT
N-Gp——

ON CPU

PT5-u

BACKPLANE

_pTs.

J1-2

+5C

PTE-

pTe t

J1-5

H744

GND

Ji1-4

GND

vs 2

+7!;L

J1-5

H744

w13

GND

J1-4

J
{

—

#H7e20

NO3 a5

| POWER SUPPLY

y2.§

GND

1/0 CABINET

FANS
120 VAC 1A

10
it RN
AIR FLOWi
J-5

DIA/DM20
A

SENSORS (w—dur-a GND
TO 863

JUMPERS

-6

\¥

POWER{‘—' Ji-1 CROBAR

CONTROL

le— Jy1-2 GND

CROBAR

H770

J-4

I_% a5 TSN

s Jg"s
T

J1-3 GND

-15 J1-1

ND a-2
H745%

+54

-5

H76!

H744

J1-4
45?12

+58

J1-5
onp

HT4a

'3
Ji-4

—

J1-5
J1-3

H744

_s.n-a

-5
GND

-15

GRD

+54

+54
GND

GND
+5

+5
GND
GND

GND

GND
-5

-5
10 - 2198

Figure

3-3

863

Power

Control

(Sheet

Simplified

PWR20/3-11

Functional

Schematic

863

CoN

RH20

H7420 NO.1

J2é

-6

-2

5 41 -5

-3

GND

-2

-3

GND

-2

gy -5

-3

GND

-2

GND

Ji1

-3

-5

-4

-5

GND 4 _ 4

*5 41 -8

H744

GND
;y . 4

H744

L
I

GND

oND

GND
;i . g

HY44

J27

GND

-5

H7420

GND

NO.6

MA20

J2-6

-8

+20

J1 -2

GNO

-5

+20

+20
H754

-2

GND

+20

-8

+20

HrS4

Jr -2

GND

HT54

-2

-8

H744

J1 -4

GND

-3

GND

-2

GND

-5

GND

H744

J1 -a

-5

128

H7420

-3

NO.7

J2-6
J1

+20

HT754

y1
J1

+20

H754

-5

+20

-2

GND

-5

+20

Ji -2

GND

+20

-8

+20

H754

-2

GND

-2

-§

WT4a

-a

GND

-3

GND

-2

GND

-5

GND

H744

-4

-5

-3

-5

"0-2199

Figure

3-3

863

Power

Control
(Sheet

Simplified
6

PWR20/3-12

Functional

Schematic

J2
9

H7420

NO.4

MA20

J2 -5

J2-6
J1-5
+ 20

J1 -

+20

GND

H754

J1-5
+ 20
H754

‘2

J1-

H754

J1-2

J1-8

H744

J1-

Ji1-

+20

GND

+20

GND

J1-2

Ji
-5

GND
GNO

J1-5

H?420

[

GND

-2

J1-

J30

+5
+5

GNO

-5

NO.5

J2-5

J2-6
J1-5

+20

H754

+20

1..

Jr-2

GND

J1-5

+20

J1-

H754

+20

GND

y1-5

H754

Jr-2

J1-

H744

+20

GND

Ji- 4
J1-

J1-

-5

Ji-

H744

J1-

GND
GND

GND
GND
-5

-5

10-22¢c0

Figure

3-3

863

Power

Control

(Sheet

Simplified
of

PWR20/3-13

Functional

Schematic

shown

the

applied

the

breaker

CB1.

indicating

illustration,
863

Power

Indicators

the

presence

For

120

Vac

operation,

that

each

indicator

associated

jumpers

are

series

with

Three-phase

and

line

and

removed

phases

neutral.

that

applied

outlet

J31.

T1.

Jumpers

operation.

For

120

Vac

pins

and

J16-3,

only

one

and

R1,

R2,

indicator

the

used

between

jumper,

between

shorted,

its
the

connected

neutral.
J23

Power

either

120

are

and

pins

are

between

outlet

J16-2

circuit

respectively.

and

jumpers

operation,

Auxiliary
for

operation,
and

and

Vac

line

main

directly
240

power

illuminated,

and

unswitched

are

between

applied

3-phase

75-ampere

For

each

connected

1is

and

resistors

transformer

operation,

12,

resistor

via

11,

47K

Stepped-down

J16-1

Control

unswitched

primary

wvia

Supply

Vac

placed

J16-4.

J16-2

CB10

and

via

240

Vac

between

For

240

J16-3,

Vac

required.

Both

Vac

bridge

rectifiers

output

These

-15

value,

Vdc

100

however,

the

indicator

Fault

Before

POWER

flip-flop

fault

are
The

bridge

applied

outputs

mA.

W7000.

other

are

the

five

(phase

the

regulated

resetting
well

voltages

yielding

and

+18

Vac

applied
15

Vac

provides

sepgrate

vdc

the

(indicator

the

PWR20/3-14

input

provides

outputs

the

power

storage)

driver.

full-wave

regulator

output

+15

Vvdc

outputs
W7000

control

¥30

vdc.

circuits,
@

reach

mA,

rated

high,

logic

flip-flops

as
the

When

R-S

flip-flop

associated

LED

associated

with

OVERRIDE.

CKT

BRK

none

lines

are

high,

(LEDs

and

Regulator

outputs

the

turned

input

off.

reset,

storage

flip-flops

(circuit

breaker

tripped),

these

three

the

also

reach

driver

and

are

indicator

conditions

associated

turned

rated

off.

value,

the

are
DOOR

exists,

fault
When

its

OPEN,
the

indicators

the

POWER

W7000

line

goes

low.

Three-phase

transformer

T2,

secondary.

whose

The

outputs

applied

which

tied

superimposed

360

value

signal

3-phase
the

the

input

usec

one-shot

remains

low.

This

Up-Down

gate

energizing

(contacts
open,

the

now

the

CROBAR

When

the

inverted

POWER

and

the

together

ANDed

(for

compared

with

repeatedly

power

yield

control

reference.

its

triggered

the

output

logic

POWER

the

POWER

DOWN

power

can

after

WARNING

switch

POW
- ER
DOWN

contacts

the

REQUEST

with

applied

line

OVERRIDE.

goes
If

PWR20/3-15

peak
the

the

DOWN

value,
LOW

Power
thereby

1line

contacts
main

contacts

are

Switch

the

that

high,

the

3-phase

with

nominal

with

component
The

rectifiers

Primary).

associated

long

and

remains

causes

Detector

primary

full-wave

POWER

Voltage

three

detector

POWER

Low

feeds

seconds

the

open).

and

(grounded),

the

wye-connected

condition

the

ripple

relay

switched

Approximately

has

secondary

are

system.

are

opened,

opened.

Panel

low.

closed

This

override

signal

condition

exists,
the

both

output

POWER

inputs

low.

This

indicator

ANDed

the

Fault

output
Fault

with

(LED)

POWER
Reset

the

inadvertently

the

while

statement

holds

indicator

LEDs.

output

turns

from

Because

AND

for

the

Panel.

the

high,

associated

POWER

REQUEST

signals

power

are

high.

Therefore,

control

logic

cannot

applied

the

system.

flip-flops

that

(low)

supply

low,

R-S

that

the

auxiliary

both

gate

power

true

Switch

(low)

gate.

are

the

associated

flip-flop

gate

low

POWER-ON

the

the
reset

The

drive

same
the

If the LOCAL-REMOTE switch on the pilot control board is in
the

REMOTE

grounded

this

position,

through

case,

control
from

+24

relay

the

Vdc
on

POWER

the

full-wave

then

pilot

the

J15-3,

J16-2).

energized,

relay

that

main

panel

are

distribution
power

breakers,

through

J30).

voltage

normally,
KL10-C

applied

the

within

also

long

the

board.

When

the

power

faults

D5)

This

jack

power

are

the

power

System.

PWR20/3-16

causes

J9-3,

relay

power
3-phase

through

outlets

power

comes

panel

the

pilot

(path

control

and,

the

which

detected

863

Panel.

Vdc

input

+24

pilot

and

distribution

energized.

specification,
primary

D4,

The

primary

switched

Switch

center-tap

directly

the

contactors

remaining

supplying

Power

the

diode

phase

J16-1

switch

(diodes

J16-3,

energized,

cathode

control

rectifier
to

applied

transformer-coupled

the

circuit

(jacks

and

the

control

remainder

J24

input
functions

the

Switching
from

the

LOCAL-REMOTE

REMOTE

switch

position

the

pilot

LOCAL

control

position,

board
grounds

the cathode of diode D1 ana has essentially the same effect
as

closing

case,

the

primary

outlets.

The

the

pilot

DEC

Power

Two

ways

is
ON

switch

the

used:

power
POWER

LOCAL-REMOTE

that

POWER

switch

made

control

the

available

switch

must

the

relay

LOCAL

can

normally

main

shutting

circuit

down

opening

the

POWER

Opening

CB1

removes

all

power

from

POWER

switch

described

When

J8-1

Storage

goes

power

control

kept

this

power

closed

when

the

position.

Note

also

externally

high

lines

line

closed.

(see

(PWR

are

the
the

controlled

the

CPU.

3-4

high),

the

13-second

are

closed.

PWR20/3-17

and

Panel.

closes
the

the

POWER

sequence,

five

which

Indicator

indicator

the

Approximately

Switch

(A)):

extinguished,

and

are

Power

Opening

POWER

triggered,

system

863

the

system

the

power-down

Figure

REQUEST

switch

reset,

logic

WARNING

lines

CBi1

predetermined

follows

flip-flops

Panel

1is

WARNING

provides

Switch

switched

the

power

breaker

Control;

and

Panel.

Bus.

opening

CROBAR

Switch

one-shot

POWER

DOWN

later,

the

in
and

the

the
POWER

CROBAR

OFF

POWER REQUEST

ON l

o—————13s¢c ———
|

]

ONE-SHOT TIMER

|
X

POWER DOWN

I
)
'
N

POWER WARNING

I
]

—q5ms:¢—

]
A. Normal power

off sequence

t3sec

i B

CROBAR

]

ONE- SHOT TIMER

1 —————————— ]

POWER DOWN

l _________ - ..:

CROBAR

[ ___________ }
4

]

= 5ms

_f_

POWER WARNING

B.Effect of (two)

AC line fluctuations
10-1853

Figure

3-4

863

Power

Control,

Power

PWR20/3-18

Down

Sequencing

the

LOCAL-REMOTE

REMOTE

position,

de-energized,

This
power

the

ground.

POWER

line

will

control

power

from

output

relay

will

not

opposite

When

board,

EMERGENCY

grounds

J2-2

and

has

and

not

the

outlets.

J2-2

pins

are

and

relay

switch

same

effect

given

K2.

the

output

returns

high,

J2-3

the

POWER

DOWN

the

pPilot

currents

coil

from

being

the

Switch

and

the

logic

shorted,

Reapplying

center-tapped

the

until

that

is
will

contactors

one-shot

pins

OFF

board

control

energized

the

that

possible

pPower

that

through

POWER

board

closing

flow

the

energized.

Panel
the

POWER

line.

cooling

fault

LED

override
Switch

in
is

CROBAR

stops

flowing

the

Power

disabled

Panel

triggered
WARNING

air
(No.

flip-flop

long

preventing

the

two

control

switched

the

these

Closing

DOWN

shorting

directions

that

relay

the

closed,

relay

outlets

one-shot

Pilot

the

While

the

then

power

switched

board.

will

13-second

DOWN

relay

the

removes

switch

will

and,

lines

(high),

light,

the

will

same

closed.

These

the

one-shot

therefore,

relay

removes

the

three

the

power

and

the

Fault

set.

FAULT

one-shot

POWER

output

Pilot

from

the

PWR20/3-19

cabinet,

DOWN
5

lines

the

and

POWER

later,

remain

Closing

the

Control

Board

switched

will

the

indicator

Approgimately

activated.

will

13-second

time,

rate

light

Logic

then

the

closes.

the

will

Control

line

de-energizes

the

closed

POWER

and,

outlets.

DOWN

line

an overtemperature

a similar

open,

cabinet door

cooling

circuit

fault

Pass Assembly,

Series

the H761

breaker trips

exists,

condition

will exist as did for air flow. The main difference is that
no

indicator

are

flip-flops

BKR and

associated with CKT

DOOR

OPEN.

(AC LOW line high)

When an AC LOW condition

13-second one-shot in the power control

to the
(Figure

time,
is

closed.

later,

5 ms

Approximately

line

POWER DOWN

the

Closing

the OVERRIDE

(POWER DOWN,
condition.

while

full

OVERRIDE

(LED

No.

Control.

power

line,

the AC

inoperative

the

removing ac power

from

causing

a similar

LOW

light

POWER

the

1line

PWR20/3-20

The

the

kept

event
be

fault
the

low).

fault

corrected

When

the

indicator

863

Power

also ANDed with the

indicator

fashion.
that

circuits

output of

the

associated

blinking

the

system.

the

enables

the

condition

the oscillator

LOW gate,
(AC

fault

closed,

CROBAR)

applied

still

providing

and

the

applied

to blink

inhibits

enables

The output of

PWR REQUEST

Panel

This

8),

relay

the power down

switch disables

POWER WARNING,

switch is

oscillator

the

causes

outlets.

switched

Closing

same

(POWER UP-DOWN)

CROBAR line

the

pilot control board to be de-energized,
the

at the

the POWER DOWN and POWER WARNING lines

a result,

closed.

input

is high

logic

triggered and,

the output of the associated NOR gate

low.

are

The one-shot

(B)).

3-4

the

exists,

OVERRIDE

the

Switch

signal

low voltage

detector

When

the

input

line

voltage

the

drops

below

the

preset

signal

goes

high

and

the

863

sequence.

The

one-shot

power-down

value

(nominally

Power

power

from

coming

When

the

input

line

voltage

returns

LOW

signal

goes

and

863

The

POWER

WARNING

status

reapply

and
LOW

signal,

power

the

CPU

the

POWER

one

ON
of

present,

the

machine

the

fault

until

placed

indicator
ON

3.2.3
The
2

-15

Auxiliary
contains

regulator.
manner.

circuit

through

amplifier

input
the

Consider

of
V

the

from

seven

fault

first

power-down

circuit

Q9,

Zener

through

board

the
and

manually

the

powered

machine

five

(see
+15

operates

and

voltage

the

divider

diode

(or

first

regulator

Q12

resistor

conditions

fault

opening

breaker

regulator,

the

remove

Panel.

cannot

only

seconds.

lamps

the

(CB1).

Supply

regulator

E6,

The

reset

Supply

the

and

corrected

Power

operational

output

Switch

can

reference

the

logic

sequence.

dependent

necessity

POWER-ON

the

main

are

LOW

value,

without

Power

Each

comprising

transistor).

applied

nominal
a

control

period

executes

condition).

Auxiliary

executes

power

the

automatically

actually

the

for

functions

switch

driver
or

the

Vac),

can

will

detector

and

the

override

W7000

7),

same

switch

W7000

CROBAR

comparison,

POWER

the

operating

the

back

voltage

Control

prevents

low

D15

regulator,

essentially

first

(i.e.,

external

(5.1

resistor

PWR20/3-21

Vdc).

3-3,

of
R43.

sheet
and
the

the

2N3790

approximately

amplifier,
sensing

Figure

Vdc

1is

operational

The

negative

E6,

tied

When the +5 V output decreases, E6 drives Q9 on, thereby

developing a base current for the external transistor. When
that transistor is turned on, the +5 V output will be
increased to the desired level.

Raw voltage for the +5 V regulator is obtained from the
full-wave bridge comprising D1 to D4, which has a 15 Vac

input. The external 30,000 uF capacitor provides filtering
and energy hold-up

(approximately 100 ms).

Transistor Q12 provides current limiting for the +5 V regulator
and is used for detecting a shorted output. Overvoltage

protection is provided by 02, D19, C8 and R23. For example,
if the series pass transistor (2N3790) becomes shorted, the
+5 V output would rise toward approximately +15 Vdc.

protect the 863 Power Control logic, the SCR (Q2) would turn

on, effectively shorting the output until the overvoltage
condition

corrected.

The +15 V operational amplifier (ES5) has a 5 V input which 1is
obtained by means of a resistor divider tied to the +15 V

output. If the +15 V output decreases, E5 turns on Q4 which,
.
in turn, causes Q7 to draw more current, increasing the output

Raw dc—voltage for the +15 Vv (and —15.V) regulators is obtained
from the full-wave bridge comprising D5 through DS8.

PWR20/3-22

The

-15

(pin
and

tied

-15

input

operational

ground.

outputs

(pin

amplifier

resistor

determines

E2.

the

Q10,

turn

increasing

the

-15

Transistor

Q6,

comprise

power

circuits

the

for

this

used

the
+5

W7000;

for

5.7

diode

The

Vdc,

between

the

+15

negative

decreases,

the

which

will

cause

D21,

Zener

D16,

and

Vdc

outputs

base

but

junction,

reference

output.

producing

(the

purpose).

base-to-emitter

for

the

integrated

W7000

(emitter

C22

cannot

follower)

because

the

output

approximately

the

drop

across

vdc.

the

logic

-15

that
E3

R35,

supply

approximately

Detection

resistor

voltage

output

will

its

divider

amplifier

on,

has

-15

operational
turn

(E2)

the

voltage
2

pins

sensing

and

(D20,

R19,

output

and,

reached

rated

decreases,

W7000

detect

the

input

detector

the

volts,

the

output

circuit

R12).

the

(pin

therefore,

output

included

output.

output

exceeds

Other

(D14,

R11)

and

goes

(POWER

also

low.

all

When

-15

UP)

the

low,

goes

after

the

side

rises.
12

inputs

R28

goes

+15

This

the

voltages

W7000

value.

PWR20/3-23

the
circuit

high,

input

are

sensing

When

causing

low.

E3.

the

1low,

decrease

rises,

When

inputs

the

that

the

goes

normal

have

high

the

input

that pin

low,

high.

This

causes

which

turn

shuts

down

the

delay during

rated value.

the

LED

D15,

D16,

rectifiers.

The

outputs

are

ripple

component with

High-frequency

noise

to pin

C10.

divider

input

The

on Q5.

and turns
positive
at

When Q5

ground.

determined by voltage
thereby

inhibiting

1is

R12.

and

point,
at

a
dc

R32-R33.
5.

PWR20/3-24

of
1

level

input

Q3.

positive

capacitor C15
12

capacitor

resistor

base

the

approximately

and

This

primary).

emitter goes

full-wave

to produce

resistor

and

divider

gate

form three

R11,

turns on,

reach

When pin

fault

863

the

enables

This

voltages

attenuated by

of E1

At this

direction.

(for

filtered by

goes positive,

ripple

the

reset

as pin

long

together

360

R10,

function

sequence.
to

and D19

tied

Zener diodes

cancelled by

When

consisting

high,

Detector

D18,

D17,

D11,

Diodes

1lit.

longer

Voltage

Low

basic

the W7000
as

E4 will

output

condition.

POWER UP
no

Its

high,

lights

system.

power-up

the

low after

(D24)

LED

The

indicating a

W516

3.2.4

to go

then

amplifier.

initially

to be

line

and

high,

goes

time

grounded,

operational

circuits,

goes

decreases,

POWER UP

the

voltage

LM301

provide

line

charges
is

essentially

Vdc,

also

now

low,

When
and

the
its

peak

the

collector

ripple

voltage

rises

reached,

+5.7

Vdc.

This

turns

off,

allows

9 of E1 to go high, permit£ing the sampling of volta
ge on pin
2

E1.

voltage

the

on pin

output

after

the

voltage

(AC

then

continues.

prescribed

limits,

one-shot

drops
AC

below

LOW

goes

low.

the

C15

the

discharges

long

the

prescribed

negative

limit,
down

greater

triggers,

then

the

keeping

C15,

and

remains

than

and

discharge,

longer

for

cycle

within

input

system

time

the

transition

charge

triggered.

shutting

voltage

continues

continually

capacitor

input

high,

one-shot

LOW)

peak,

and

voltage

triggers;

least

the

Field

seconds.

3.2.5

G8017

detailed

schematic

Maintenance
on

various

board

Indicator

Print
fault

contains

used

and

duty

and

falling

NE555

shown

through

R10

greater

than

CC)

and
the

Indicator
when

shown

oscillator,

the

accurately
The

Figure

first

R11.

When

used

simplified

with

When

frequency

two

triggered

block

The

{(E2).

free-running

can

turn

occurs.

circuit

controlled

circuit
A

malfunction

stable

both

Driver

timing

waveforms.

monolithic

capacitor.

power

The

G8017

NE555

are

reset

When

the

indicators

highly

resistors

Set.

cycle

Driver

external
and

diagram

the

begins

charge

3-5.

threshold

applied,
the

capacitor

voltage

(i.e.,

PWR20/3-25

rises

greater

than

value

T Vee

5
o CONTROL

VOLTAGE

THRESHOLD
(3]

- U

COMPARATOR

. C8

LT 10uf

Ve
RH-

|
i

47K

t
|

S
3R

]

TO PIN6

\
|

Vee

2
COMPARATOR ——0 TRIGGER

]

L AAA~- 7

RiIO

62K

FLIP-FLOP }——o RESET

OUTPUT
STAGE

ouTPUT

1 =

GROUND

10-1834

Figure

3-5

NE555

Timer,

Simplified

PWR20/3-26
I

Block

Diagram

approximately

2/3

discharging

the

voltage

across

less

than

is
the

cut

off

output

falling

Vee)s,

through
C8

the
is

approximately

and

charges

capacitor

discharge

less

1/3

recharges
3

the

than

the

trigger

the

R10

exponential

and

discharges.

PWR20/3-27

triggered,

transistor

Vce)»

through

(pin

voltage

discharge

and

R11.

waveform

7).

When

(i.e.,

transistor

effect,

rising

and

3.3

861-D

POWER CONTROL

The 861-D Power Control controls application of ac power from

the 863 Power Control to the 2040 front-end device power

supplies and controllers
and Floppy

Disk

(i.e., the PDP-11/40, LA36 DECwriter

system).

Block Diagram Analysis

3.3.1

A block diagram of the 861-D Power Control is shown in Figure

3-6. Major sub-assemblies include a power line filter, circuit
breaker and relay assembly, pilot control board, and switched
(with spike suppression)
functions

are

performed:

Control large amounts of power by control signals of
small

and unswitched outlets. Four basic

power

content;

Distribute primary power to controlled devices
conveniently;

(front end power supplies and controls)

and

Filter primary power to controlled devices;

Remove primary power from controlled devices in case
of overload or temperature conditions automatically.

Operation of the 861-D is summarized as follows: When the

circuit breaker

(CB7)

is turned on, power 1is supplied to the

unswitched outlets and to the switched outlets,

when the

LOCAL/OFF/REMOTE switch is in the LOCAL position.

The circuit

breaker opens automatically when an overload condition exists
at a power outlet or within the power control.

PWR20/3-28

—————ad

—————of

—

———»

r"HASE.Z_—

Al
LINE
FILTER

g2
@3

PILOT

CIRCUIT

LAMPS

BREAKER

RELAY

wfi§w|¢¢¢¢|

L_.___.

GND ——»

r!;I-TA.S-E?—

15560

POWER REQUEST ——
EMERGENCY

SHUTDOWN ——y
COMMON —»

PILOT

CONTROL

LOCAL /OFF/ REMOTE ——»f
THERMAL SWITCH —e
10-2201

Figure

3-6

861-D

Power

Control,

PWR20/3-29

Block

Diagram

LOCAL/OFF/REMOTE

switch

with

the

means

When

the

power

controller

outlets

not

are

the

regardless

thermally

controlled

condition
and

outlets

resets

the

controller

3.3.2

Detailed

3-7

Control.

Refer

Maintenance

power

drops

conditions

the

LOCAL

the

pilot

lamps

position

also

when

signal

are

lighted

connected

the

power

the

control

disable

the

overtemperature

The

switch

ambient

120°

outlets

switch.

provided

the

below

I3)

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Description

simplified

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loads

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whenever

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high

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removing

lines

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across

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ground

present

light.

circuit

five

terminal

contains

filter

present

three

control

capacitors

this

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output

contact

each

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energized

energized,

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side

voltage

energized

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applied

filter

power

3-phase,

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components;

output

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impedance

5-wire,

filter.

series

components.

4-pole,

line

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the

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which

provide

line

power

ground.

connected

capacitors

Vac

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associated

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energized.

across

the
when

the

relay

remaining

lines

switching

control.

3.3.3

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Figure

3-7

shows

schematic.

which

Control

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allows

power

functions

are

the

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field

circuit

(D4,

D5)

turn-on

control

shown

the

lines
bottom

the

Shutdown)

line

lines

from

Request)

(from

the

lines

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the

pins

thermal

associated

full-wave

are

the

and

DEC

Control.

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the

voltage

applied

coil

connect

the

secondary

the

power

disable

bus;

switch)

are

connected

switch

and

current

center-tapped

relay

transformer.

relay.

board,

connector

full-wave

(Emergency
1

power

each

the

DEC

pins

rectifier

field

connected,

rectifier

the

with

circuitry

turn-off

full-wave

J3)

figure.

LOCAL/OFF/REMOTE

and

portion

from

the

circuit

K1.

the

line

Power

controlling

center-tapped

transformer.

emergency

861-D

simplified

contains

center-tapped

(J1,

rectifier

(Power

and

consists

the

board

the

relay

basically

Three

Description

control

accomplished
coil

Circuit

control

outlets

loaded

connects

pilot

remote

switched

the

Board

bus.

the

Two

enable

additional

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and

J4-2,

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flows
field

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REMOTE

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coil

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closes

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lower
to

the

relay

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to

power

applied

across

the

field

coil

control.

PWR20/3-33

associated

with

the

This

energizes

pins

and

the

are

connected

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coil

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through
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to
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before

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K1

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the

3).

center-tapped
through

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potential,

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transformer.

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not

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and

outlets.

provides

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are

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supply

relay

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controlled

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field

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instances

connection

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provides

connection

the

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line

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coil

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normally

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system.

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and

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Bus.

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1200

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Description

a simplified schematic diagram of the H7420

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signals

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integrated
voltage

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precision

circuit

reference

transformer

prime

the

purpose

this

control

noise

tripping

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cooling

fan

input.

secondary

the

power

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from

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the

control

power

line,

power-fail

board.

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Vdc

the

input

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sheet

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between

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power

out

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board,

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board

+15

control

230

control

provide

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contains

external

H7420

power

Primary

for

filter

Volt

power

Power

3.4.1.2

+15

the

secondaries

the

inadvertent

power

taken

device

TB1

regulators.

preventing

Circuits

power

either

and

through

transformer

assembly

(J1-1

thereby

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Vac

(terminals
board

T1.

regulator

operation

applied

circuit

the

regulator.

from

the

voltage

comprises
amplifier,

schematic

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rectified

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power

switching

20-to-33

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supply

regulator

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input

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temperature-compensated

error

amplifier,

series-pass

power

transistor, and current limiter; VéUT (pin 10) is not used in
this

application.

PWR20/3-37

The

voltage

applied

the

base

controls

the

current

through

controls

the

current

flow

Q6,

Q7)

the

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Q6

level

provide

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+15

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overall

shifter.

vVvdc

for

circuit

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through

voltage

pass

the

other

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diode

D17

used

the

regulator

output

capacitor

regulator

output

filter.

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ground

providing

emitter

decay

operation,

C10).

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device,

voltage

C10.

and

across

type

and the

These

off,

D12

circuit

output

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thus

reference
to

supplying

back

voltage.

whether

the

input

where

turns

output

pass

voltage

increases.

PWR20/3-38

a
of

voltage

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may

output

compared

transistor
level

used

thus

square-wave
the

appears

varying

D12,

make

off,

basically

regulation.

E1,

diode

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square-wave voltage

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most

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the

period,

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for

generating

terminals.

sensed

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components

when

output

and

with

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the

controlled,

according

turned

fixed

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applied

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for

filter

average

which

averaging

path

voltage

pre-driver;

standard

and

the

consists

choke

clamp

(04,

E1.

and

subsequently

transistors

regulators

the

and

curcuit.

switching
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transistor

transistor,

transistor;
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power

the

an
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varied

voltage

with

and

decreases

off,

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one

full

operation

follows:

+35

vdc)

applied

+15

Vdc

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level,

constant

build

through
this

output

voltage

output

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+20

Vdc

linear

constant

L1.

causes
the

same

point)

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clamped

ground.

becomes

forward

biased

ensure

off,

current

then
the

increase

turned

once

off;

already

L1.

current

capacitor

causing

C10

the

When

the

approximately
the

emitter

decays

through

D12,

back

emf

the

effective

and

off

turned

off

and

the

value

across

increase.

reaches
Q7

can

ramp

output

turning

present

voltage,

E1)

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output

time,

and

monitored

used

the

current

shuts

voltage

Pre-driver

high

regulator

voltage

(+15

the

across L1.

changing

and

Vdc,

which

then

absorbs

+15.2

turned

cycle,

L1.

gain

relatively

short

period.

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to

decrease,

reached,

again,

predetermined

causing

beginning

voltage

another

superimposed

turn

on.

cycle

the

predetermined

maximum

(+15.2

values

When

maximum

and

when

circuit

E1.
the

the

minimum

action

also

referred

causes

operation.

Vdc)

and

PWR20/3-39

turns
as

minimum

reached,
E1

voltage

approximately

This

output

reached,

output

E1
Q7

begins

+14.8

Vdc

conduct

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ripple

detected

(+14.8

Vdc)

turns
on.

"ripple

This

off
type

regulator.

The

overcurrent

and

through

however,

when

amperes,

the

RETURN

sensing
R6.

the

Transistor
output

current

line,

turns

draws

transistor

E1,

turns

Q1.

latched

on.

base

turns

Also,

current

R6,

not

D2,

and

on,

the

diode

series

effectively

shutting

off

and

on,

the

+15

pass

stopping

voltage

divider

(R2,

provides

current

line

allows

biased

begins

approximately

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the

turns

conducting;

approximately

turns

Q2,

off

and

Q1,

normally

exceeds

on.

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shuts

reaches

off.

through

Transistor
Now

consists

sensed

correctly;

regulation.

circuit

decrease.

volts,

turn

keep

R1)

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the
which

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off,

again

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begin

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cycle.

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overvoltage

components:

crobar

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R37,

diode

Q9,

the

following

R40,

C13

and

input

thyristor

08.

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(Q8)

D18

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small

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base

voltage

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emitter

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current.

current

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drop

triggers
V

continues

forward

voltage

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the

cause

resistor

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because

trigger

sensing

shorts

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output

biased,
is

conduct.

thyristor,
to

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to
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turning
and

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clamping

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rise.

ground

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conducts,
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line

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current

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on.

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pass

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gate

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on

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capacitor

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3.4.1.3

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line

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to

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power

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volatile

time
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circuits

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to

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differential
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Q12

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pins

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harness

fail

initialize

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similar

manner

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the

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power

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turn-off

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LO

logic.

are.

sequences.

decrease

the

lines
signal

Figure

example,

For

lines

result

are

power

1is

restored,

before

3-10

also

shows

the

removed

applied

the

H7420

the

power

—l:— 95

132 VAC

—op—

0 —it
0

[" “""*
[

!
|

:'
!

L0200

+15V,

| Il

I~ MAX.
l

| ']'

is removed.

+8V

---

*ov

+—e DC LO (H7420)

0-1

o—l—-—r—r—- -15V

}

‘

t—

(H7420)

(H745)

T TT A
T

04---!

(H7420)

o-1

-5V

OFF

;L +5V (H744)

+3.5v

~15V (H745)

processor operation

POWER

’

+3.5v

for 70ms after AC

——

+5v

VAC

is internally inhibited

[ Ac Lo

t
|

+5V (H744)

-» DC

POWER

+{5V

+15V (H7420)

.001

025

.030‘.__

| IMAXI

F— ‘max—=1 |
—o; I<—| 002 NOM.
TIMES SHOWN ARE IN SECONDS

a. TURN ON

b. TURN OFF
CcP-201S

Figure

3-10

H7420

Power-Up

and

Power-Down

PWR20/3-45

Sequencing

3.5

H744

REGULATOR

VOLT

The H744 Regulator circuit is shown in the Field Maintenance

Print Set (drawing D-CS-H744-0-1) and includes a regulator
an overcurrent sensing circuit,

circuit,

and an overvoltage

The schematic shown is for a +5 Vdc Regulator,

crobar circuit.

where output pins J1-2 gnd J1-5 provide +5 Vdc; pins J1-3 and
J1-4 are grounded. To obtain a -5 Vdc regulated output at pins
J1-3 and J1-4, pins J1-2 and J1-5 are grounded. The following
paragraphs describe the positive regulator circuit, over-current
sensing circuit and overvoltage crobar circuit.

Detailed Circuit Description

3.5.1

As shown in the schematic

(D-CS-H744-0-1),

the 20-30 Vac

input from the associated H7420 Power Supply is rectified by
full-wave bridge D1

to provide a dc voltage

(24 to 40 vdc,

across filter capacitor C1

depending on line voltage)

and

bleeder resistor R1. This dc voltage is regulated by the circuit
comprising transistors Q2 through Q5 and monolithic integrated
circuit E1, which is a precision voltage regulator.

Filter capacitor C1

(31,000 uF)

is used to obtain a delay of

approximately 20 ms in the event of power failure.

H744 +5 V Regulator Circuit

3.5.1.1

Figure 3-11

is a simplified diagram of precision voltage

regulator E1.

This DEC723 integrated circuit comprises a

temperature—compensated voltage reference amplifier,

A¢

ouT

{pin

series-pass power transistor, and current limiter;
10)

not

used

amplifier,

error

this

application.

FREQUENCY
v+

TIN

COMPENSATION

1&)

Nve?bpufi o

VREF o)

ERROR

TEMPERATURE

AMPLIFIER

COMPENSATED 7%’
ZENER

‘
SERIES

PASS

TRANSIS TOR

VOLTAGE

REFERENCE

(10

AMPLIFIER

p—————ovour

Y'Y
(9)

—T
ovz

NONINVERTING (5]

CURRENT

INPUT

LIMITER

(Part no. 1910415)

(2)

(3)

CURRENT
LiMiT

CURRENT
SENSE
10-1976

Figure

3-11

H744

Precision

Simplified

Voltage

Diagram

PWR20/3~-47

Regulator

E1,

The

voltage

applied

the

base

controls

the

current

through

controls

the

current

flow

through

Q5)

pass

level

the

raw

power

transistor

transistor,

the

voltage

other

and

regulator

are

diode

used

Most

the

input

collector-emitter

Q5.

This

i1s

above

that

required

supplied

vdc

The

for

E1.

voltage

+15

Vdc

well

input

subsequently

pre-drivers;
with

(Q2

circuit.

Zener

transistors

and

input

operate.

the

+15
the

that

through

overall

transistor;

shifter.

provide
across

and

voltage

necessary

1is

absorbed
because

for

while

still

retaining the ability to switch pass transistor Q2 on or off
by

drawing

current

down

The

output

circuit

through

the

H744

switching

reqgulators

and

choke

and

capacitors

make

L1,

used to
thus

the

output

regulator

providing

operation

voltage

which

decay

consists

output

path

turned

applied

emitter

Regulator

for

and

across

Q5.

standard

"free-wheeling"

and

filter.

emitter of Q2

the

clamp

the

C9.

These

for

most

diode

DS,

components

Free-wheeling

diode

shuts off,

ground when Q2

L1.

off,
D5

generating
the

input

a
of

square-wave
the

filter

(L1, C8 and C9). This type of circuit is basically an averaging
device,

and

voltage

the

square-wave

output

voltage

terminals.

PWR20/3-48

appears

average

varying

voltage
The

the

may

output

compared

with

level

limits
+5.05

(see
Vdc

During

conduction

varied

voltage

transistor
voltage

fixed

and

Figure

full

+30

applied

Vdc)

Vdc

This

and

level,

absorb
level

(which

through

output

shuts

(+5

forward

biased

Q@2

can

L1.

turning

the

increase

turned

pass

whether
Defined

are

and

high

L1.

output

+25

Vde

linear
time,

current

decays

back

emf

the

L1.

present

across

L1.

ramp

current

capacitors

voltage,

causing

When

PWR20/3-49

which

the

+5.05

Pre-drivers

relatively

time.

D5,

gain

lower

operates

increase.

through

and

approximately

effective

off

upper

already

emitter

output

and

the

(approximately

the

same

off;

voltage

causes

approximately

regulator

reaches

and

turns

the

E1)

the

where

cycle,

point)

then

regqulation.

E1,

t1%).

the

output

this

vdc

constant

back

voltage.

the

(average)

supplying

changing

current

(i.e.,

across

monitored
off,

used

vdc

output

thus

increases.

for

fed

according

voltage

this

ground.

are

off,

turned

then

constant

build

reference

operation

follows:

and

3-12)

+4.95

the

controlled,

sensed

decreases

and

one

period,

short

the
output

vdc,

clamped

becomes

and

ensure

period

Q4
that

Q2 OFF

_______

— _REGULATED

N 4.95V (TYPICAL)

OUTPUT

ov
11-0098

Figure

3-12

H744

Regulator

Waveforms

Conversely,

once

decrease,

is reached,
again,

causing E1

superimposed
maximum

values

When

E1.

+4.95

action

3.5.1.2
The

R25,

R26,

+5.05

H744

Overcurrent

sensing

Programmable

the

forward

ohms)

anode

of
to

PUT
Q7,

transistor

Q7)
Q7

off.

below

amperes

removed.
allowed

that

turn

on.

This

Q1,

output

the

across

current

biased

output

voltage

turns

regulator

continues

then

discharges

until

repeats.

PWR20/3-51

at
at

condition
is

again

the
the

pass

maintained

regulator

overload

decreased

the

(present

which

the

exceeds

off,

and

R6,

fixed

current

through

causing

potential

on,

resistor

cycle

circuit

sensing

until

the

and

Transistor

turn

programmed

The

off

regulator."

the

type

mode

and

turns

Circuit

new

on,

Vdc)

however,

Vdc

ripple

(+4.95

C4.

the

and

begins

+4.95

detected

Q7,

protected.

Capacitor

consists

(approximately)

this

(PUT)

on.

Thus

minimum

"ripple

charges

Thus,

ensure

"short-circuit"
oscillate

equal

turns

required
35

and

Sensing

sufficient

voltage

This causes Q2 to conduct

reached,

output

approximately

output

turns

voltage

When

the

operation.

Vdc)

UJT

amperes,

charging.

circuit

conducting;

begin

refered

not

gate

also

value

the

(+5.05

normally

(0.02

and

cycle

reached,

overcurrent

off

to furn on.

another

predetermined

when

turned

predetermined

beginning

voltage

3.5.1.3

The

H744

Overvoltage

overvoltage

components:

crobar

Zener

Crobar

circuit

diode

D3,

Circuit

consists

SCR

D7,

D8,

the

R21,

following

R22,

R23,

and

the

SCR

(D7)

1is

Q6.

Under
at

normal

ground

small

Vdc,

conditions,

because
cause

Zener

registor

€

the

voltage

conduct.

diode

The

R21)

the

trigger

input

across

Zener

diode

conducts

emitter

continues

rise.

the
(D8

line

also),

(through

When

too

approaches

clamping

current

the

base

sensing

emitter/base

junction

becomes forward biased, Q6 begifls to turn on and pass current.
A

voltage

and

drop

triggers

line

discharge.

the

created

SCR

ground.

across

(D7),
The

R23.

turning

SCR

remains

draws

on.

The

until

gate

SCR

current

shorts

capacitors

the
C8

and

3.6

H745

The

H745

-15

Regulator

Set

volts.

VOLT

circuit

(drawing

The

REGULATOR
is

shown

D-CS-H745-0-1)

following

paragraphs

and

the

Field

supplies

describe

the

Maintenance

regulated

negative

-15

regulator

circuitry.

3.6.1

H745

shown

from

the

bridge

the

voltage

which

Filter

capacitor

3.6.1.1

This

through

H745

3-13

DEC723

(24

vdc,

depending

capacitor

and

bleeder

resistor

R1.

VOUT

(pin

applied

series
10)

the

Volt

the

pass

base

full-wave

line

comprising

integrated

circuit

E1,

regulator.

event

used

transistor,

power

delay

failure.

precision

regulator

E1.

reference

this

obtain

power

comprises

voltage

power

Circuit

diagram

circuit

the

circuit

monolithic

Regulator

used

the

uF)

simplified

not

and

(31,000

temperature-compensated

amplifier,

input

voltage

integrated

Vac

rectified

-15

20-30

regulated

precision

approximately

Figure

Power

the

Supply

filter

Description

(D-CS-H745-0-1),

H7420

provide

across

transistors

Circuit

schematic

associated

voltage)

This

Detailed

amplifier,

and

current

application.

transistor

error

limiter;

The

voltage

controls

the

current through that transistor, afid subsequently controls the
current

the

flow

overall

through

voltage

the

other

regulator

transistors

circuit.

PWR20/3-53

(Q2

through

Q5)

FREQUENCY

COMPENSATION

INVERTING _ 4)

(12)

INPUT

)

(3
ERROR

LY,

AMPLIFIER

TEMPERATURE

COMPENSATED &’
ZENER

‘

SERIES

PASS

TRANSISTOR
VOLTAGE

REFERENCE

AMPL IFIER

(10)

ovourt

(9)

0o
VZ

NONINVERTING . (5)

CURRENT

INPUT

LIMITER

{Part no. 1910415)
o

§4!

(2)

V-

(3)

CURRENT CURRENT
LIMIT

SENSE

10-1976

Figure

3-13

H745

Precision

Simplified

Voltage

Diagram

PWR20/3-54

Regulator

E1,

Transistor

and

+15

input

are

the

used

H744

allows

(=15

the

standard
D4,

choke

make

H745

The

and

decay

regulator

Transistor

basically

filter

(L1,

with

transister
voltage

level

fixed

and

voltage

when

and

applied

the

and

reference

These

05,

the
This

level

diode

components

used

shuts

Q2,

off,

thus

fed

type

according

output

PWR20/3-55

controlled

circuit

input

voltage

terminals.

(average)

supplying

back

to
E1

the

thus

decreases.

square-wave

voltage.

around

generating

across

the

centers

which

output

controlled,

off,

operation

transistor

period,

sensed

increases

Diode

the

varied

compared

C9.

Regulator.

and

transistor

and

example,

consists

and

device,

may

reversed,

For

H745

from

addition,

ground

NPN

Regulator

This

voltage

are

E}.

H745

C9).

conduction

H745

derived

ground

and

the

L1.

C8,

the

filter.

turned

varying

voltage

pre-drivers;

below

regulators

which

average

operate

pass

output

PNP

regulator

appears

The

the

for

averaging

and

voltage

components.

capacitors

conditions,

output

path

inputs

are

Regulator,

operation

H744

shifter,

circuit

and

across

various

switching

collector

square-wave

but

regulator

normal

the

level

applied

the

output

linear

output

the

correct

Regulator

most

the

E1.

Unlike

noninverting

for

providing

Under

for

Regulator,

Vdc).

clamp

and

polarities

transistor;

shifter.

source;

inverting

pass

required

the

level

external

which

regulation.

E1,

where

turns

pass

whether

the

output

Defined

are

lower

and

approximately

During

one

follows:

full

1is

already

ramp

current

the

same

time,

point)
E1)
Q2

current

the

L1.

the

off

Conversely,

once

(more

decrease

approximately
This

causes

across

then
dc

(more

voltage

the

output

the

1is

output

-15.15
Q2

Vdc,

clamped

D4,

which

gain

ensure

relatively

short

turned

and

positive),

Vdc

conduct

1is

off

again,

L1.

off,

this

turning

Choke

that

can

biased

used

causing

forward

output

beginning

linear

are

predetermined

reached,

monitored

period

the

output

Vdc

(-15

becomes

and

t1%).

changing

ground.

-15

shuts

the

through

Predrivers
of

1level

output

vdc

operates

this

(which

=15

causes

negative)

the

voltage

L1.

absorb

for

(i.e.,

constant

causing

L1.

through

-14.85

applied

Vdc

negative

effective

and

high

3-14)

regulator

and

approximately

emf

the

When

decays

Figure

-14.85

constant

capacitors

then

and

build

voltage,

and

level,

This

(see

cycle,

1is

Vdc

collector

increase
turned

-15

the

back

Vdc)

increase.

reaches
off;

vVvdc

operation

across

and

-15.15

-30

present

current

limits

turned

(approximately
is

upper

time.

voltage

begins

value

turn

on.

cvcle

another

operation. Thus, a ripple voltage is'superimposed on the output
and

detected

predetermined

maximum

(-15.15

Vdc)

and

minimum (-14.85 Vdc) values by E1. Wfien -15.15 V is reached,
E1

turns

This

type

off

and

circuit

when

-14.85

action

1is

also

regulator."

PWR20/3-56

reached,

referred

turns

on.

"ripple

POWER
ON

Q2
OFF

Q2
ON

Q2 OFF

|
|
|
-39V

— —-——Q2

|
|
i

[

Y
- =
\_15.‘5\/

=- REGULATED
QUTPUT

10-2236

Figure

3-14

H745

Regulator

PWR20/3-57

Waveforms

3.6.1.2

The

H745

Overcurrent

overcurrent

R23,

sensing

Programmable

UJT

circuit

(PUT)

normally

not

conducting;

amperes,

the

forward

ohms)

(0.04

begin
the

charging.

gate

turns

on.

off.

Thus,

ensure

PUT

the

that

(approximately)

When

Q7)

equal

biased

and

regulator

mode

until

the

overload

then

discharges

H745

crobar

current

anode

on,

(present
07,

transistor

required
below

to
amperes

"short-circuit"

to
is

again

causing

maintained

1is

resistor

pass

decreased

R18,

exceeds

potential

turns

R3,

sensing

potential

the

oscillate
removed.

allowed

this

new

Capacitor

turn

on,

and

Zener

Protection

circuit

diode

D6,

consists

SCR

D5,

R19,

the

R20,

following
R21,

C7,

C11,

Q6.

Under

normal

conditions,

because

cause

output

which

the

R2,

Transistor

condition

Q1,

turn

continues

Overvoltage

overvoltage

components:

and

repeats.

3.6.1.3
The

until

regulator

The

cycle

current

the

C3.

across

voltage

output

and

charges

off,

Circuit

consists

however,

sufficient

protected.

the

vqltage

output

the

Sensing

too

-15

small

approaches

-18

approximately
current

sensing

the

trigger

voltage

drop

conduct.

Vdc,

Zener

the

base

resistor

R19)

appears

diode

input

across

the

conducts,

¢6.

PWR20/3-58

The
to

the

SCR

Zener

-15

(DS5)

diode

line

clamping

emitter
rise,

(through

although

1is

the
line

base

that

goes

actually

negative.

becoming
When

the

biased

correctly,
Q6

turns

created

across

R21.

gate

SCR

(D5),

ground,

and

turning

stopping

draws

negative

base/emitter

becomes

on.

and

on.

The

SCR

shorts

the

output.

The

SCR

remains

discharge.

PWR20/3-59

the

junction

voltage

current

drop

triggers

-15

until

line

-15

1is
the

capacitors

3.7

H754

The

H754

circuit,

two
and

regulator,

(20-30
pins

Vac)

J1-7

and

voltage

the
1s

J1-8.

this

integrated

the

Maintenance

regulator

overcurrent

sensing

With

J1-3

outputs

regulator,

overvoltage

J1-2

-5

Vdc.

shunt

crobar

circuitry.

Description

(D-CS-H754-0-1),

input

H7420
to

circuit

includes

and

addition

rectified

Field

circuit.

Vdc

associated

regulated

monolithic

+20

sensing

schematic

from

the

circuits,

describe

Circuit

and

crobar

outputs

paragraphs

rectification,

boosting

regulator

J1-5

the

shown

D-CS~-H754-0-1)

overcurrent

overvoltage

Detailed

shown

REGULATOR

circuit

shunt

following

3.7.1

VOLT

(drawing

grounded,
The

-5

Regulator

Set

circuit

+20,

the

Power

circuit

E1,

doubler,

50-60

comprising

which

connects

full-wave

voltage

approximately
circuit

input

Supply

providing

Vdc.

Q2,

The

and

Q3,

precision

voltage

regulator.

3.7.1.1

Figure

H754

3-15

regulator

+20,

E1.

-5

simplified

This

DEC723

temperature-compensated
amplifier,
VOUT

(pin

series
10)

applied

current

through

current

flow

the

overall

the

Regulator

pass
not

base

that

through

voltage

diagram

integrated

voltage
power

used

the

precision

circuit

transistor,
this

power

other

regulator

reference

transistor,
the

Circuit

comprises

amplifier,
and

current

application.

error
limiter;

voltage

controls

the

subsequently

controls

the

transistors

circuit.

PWR20/3-60

The

transistor

and

voltage

(Q2,

903,

and

Q5)

FREQUENCY
COMPENSATION

ml&

INVERTING _ &)
INPUT

(8)

VREF o—

"
(n

ERROR
AMPLIFIER

TEMPERATURE

COMPENSATED 73

ZENER

SERIES

PASS

TRANSISTOR

VOLTAGE
REFERENCE
AMPLIFIER

(10}

[

VOouT

7Y
(9)

————o
V2

NONINVERTING . (5)

CURRENT

INPUT

LIMITER

(Port no. 1910415)

(2)

V-

CURRENT
LiMIT

(3)
CURRENT
SENSE
10-197¢

Figure

3-15

H754

Precision

Simplified

Voltage

Diagram

PWR20/3-61

Regulator

E1l,

Transistor

shifter.

level

provide

+15

absorbed

because
E1

Vvdc

the

drawing

The

output

one

for

+20

the

-5

Q10

and

The

basic

+20

Circuitry

for

used
the

the

consists

the

Q5.

voltage

This

shunt
for

necessary

while

-5

transistors

for
still

and

off

Q5.

regulator

the

required

supplied

and

transistor

two

comprises

that

emitter

other

comprises

with

above

through

pre-driver;

input

well

pass

+25

connected
between

output
C9

and

filter.
V

switch

output

ground

-5

Q4,

transistors

circuits:

ocutput.
Q10,

The

and

Q11;

Q9.

Both

transistors.

are

output

Most

when

across

pass

this

C16.

These

Diode

shuts

Vdc

+20

vdc).

output,

transistors

consists

(-5

diode

D6,

components

with

The

and

Q10.

choke

make

used

clamp

off,

thus

providing

the
a

and

the

emitter
decay

path

L1.

for

pass

this

input

output,

capacitors

toward

Vdc

down

regulator

+15

regulator

are

connection

E1.

yoltage

regulator

shunt

diode

collector-emitter

ability

regulators

output

for

circuitry

shunt

The

transistor;

Zener

input

current

the

pass

the

raw

operate.

(V,)

across

retaining

1is

operation,

applied
This

voltage

which

(L1,

and

C16).

device,

and

the

average

voltage

turned

and

across

off,

generating

the

type

circuit

square-wave

voltage

(+25

the

input

the

PWR20/3-62

input

basically

shunt

of
an

appears

sgquare-wave

the

filter

averaging
as

regulators.

varying

voltage

the

may

conduction

varied

The output voltage
compared

with

transistor

voltage

During

Vdc

L1.

one

constant

causes

C16

absorb
level

output

(which

shuts

toward

-5

turning

biased

increase

the

decrease,

reached,

current

the

off

once
a

level

across

L1.

pass

the

output

build-up,

1is

two

(-5

+20

V),

constant

through

L1.

capacitors

voltage,

increase.

causing
When

off;

the

emitter

through

emf

L1.

gain

ensure

short

turned

off

and

value

on.

PWR20/3-63

D6,

the

Vdc,

clamped

used

can

output

becomes

that

period

the

which

Pre-driver

relatively

turn

1is

the

approximately
Q2

then

voltage

reaches

decays

across

shunt

E1)

then

applied

the

output

and

operates

(approximately

This

build

point)

predetermined

causing

turns

back

effective

and

Conversely,

monitored

input)

(before

current

this

voltage

Vdc

current

changing
at

regulation.

where

whether

doubler

present

current

supplying

regulator

high

+25

this
the

forward

turned

the

output

ramp

(+25

off,

and

regulator

Vdc

with

output

voltage

linear

Coincident
and

already

+35

cycle,

the

(average)

increases.

turned

basic

regulators)

thus

voltage.

according

operation

because
the

off,

output

sensed by E1,

reference

decreases

full

the

controlled,

(+25 V)‘is

fixed

level

follows:
60

period,

time.

voltage

approximately

begins

Vdc

This

causes

conduct

again,

beginning

another

cycle

the

shunt

operation.

The

voltages

regulator
on

the

-5

+20

relative

this

because
Vvdc.

Transistor

the

tabs

until

was

increases,

the

current

the

output

the

this

+20

sensed

causing

the

ground,
from

with

depending

the

+20

voltage

respect

while
at

negative

regulator

fixed

and

bases

begin

conducting,

the

+20

met,

-5

and

ends

the

-5

Q4.

ground

output

conducting;

this

period.

the

Q10

conduct

balance

and

increases

output

two

the

during

the

between

transistors

current

basic

condition

conducting

output

current

(in

negative

-5

balance

drawn

constant,

and

respect

the

When

not

conducts,

increasing

with

change

thus

restored.

vary

remains

causes

outputs.

tends

This

bases

amount

current

output

ground;

+25

the

circuits)

regulator

the

also

-5

current

the

outputs.

3.7.1.2

H754

Overcurrent

The

overcurrent

UJT

(PUT)

08,

sensing

Q13,

Transistor

total

current

peak

not

exceeds

across

conducting;

current

sensing

M
S

on.

Q1,

Programmable

circuitry.

associated

approximately

normally

Circuit

consists

and

R4,

turns

voltage

circuit

forward

Q14,

Sensing

however,
14

amperes,

resistor

the
the

(0.04

ohms)

This

establishes

fire

PUT

voltage

Q8.

The

the

reference

Now

diode

Q14,

which

determined
action
The

(E1,

conducts

and

the

output

allows

the

off-time

the

duty

current

3.7.1.3

H754

Two

crobar

+20

The

+20

circuits
and

Zener

normal

because

cause

+24

Vdc,

Zener

diode

+24

-5

small

The

continues

rise.

biased

properly,

created

across

SCR

(D9),

the

-5

line

and

Q5.

and,

in
-5

the
V

circuit
D9,

across

on.

The

through

SCR

D3,

H754:

R24,

input
Zener

the

+20

the

on-time.

The

on.

amperes.

PWR20/3-65

for

the

and

the

SCR

(D9)

too

the

base

shorts

resistor

and

the

1is

R23)

becomes

drop

triggers

+20

Q7.

approaches

voltage

the

following

R25,

junction

cu;rent

shorts

line

sensing

also

one

diode

clamping

turn
gate

load.

consists

emitter/base

draws

this

regulator.

When

the

R23,

trigger

turn,

Circuits

conducts,

begins

period

approximately

current

R25.

turning

(through

turns

increases,

SCR

the

for

Q2.

current

the

conduct.

R37

off

overload

for

the

shutting

above

than

one

D7,

pulled

greater

Crobar

crobar

then

employed

Li.

proportion

voltage

emitter

the

sufficient

through

and

R38

thereby

keeps

limited

conditions,
the

5),

current

diode

Under

are

overvoltage

components:

Overvoltage

requlator

thus

voltage

cycle

and

This

changing

the

Q13.

increases

across

voltage

turns

off-time

output

voltage

+15

line

volt

the

source

loses

When

output.

stopping

Q2,

off

thus

(C9)

capacitor

the

on until

SCR remains

The

shuts

which

off

shuts

(V.),

+15

discharges.

manner.

Under

conduct.

again

on,

a voltage drop

the

SCR which then

shorts

The

SCR remains

connector.

set

disconnect the

power up,

load,

top,

the

the H754;

side of

located on the

next to

power down

output voltages,

the

discharges.

(C9)

capacitor

line.

the
system,

the

adjust

for

a 25 V reading

and

-5 V outputs with

the

20 V potentiometer

set

the

-5

between

its

output

power

up,

and

Regulator

adjustment

(i.e.,

(R21)

actually

from +20

VvV,

controls

necessary

sets

the

-5

(&)

H754

(R17)

the

potentiometer

procedure

[6)]

This

(e}

+20

again.

load,

[#8)

outputs

the

reconnect

[\]

down,

Power

line

-2

Then

+20 V

the +20

(R17).

-5

the

between

line

-5 V

turns

triggers

(R21)

-5 V potentiometer

the

Q12

R25.

the

(R17)

The +20 V adjustment

Adjustments

Voltage

H754

3.7.1.4

line

created across

the

on until

on.

turn

-5

the

begins

Q12

increase,

continues

Q12.

base

the

clamps

and

turns

not

D14

negative),

(more

increases

line

-5 V

the

does

D14

diode

Zener

conditions,

normal

similar

in a

functions

crobar circuit

-5 V overvoltage

The

the

V
to

and

check

and

because

overall

ground.

-5

ground

V),

adjust
the

output

while

the

output.

3.8

H770

The

H770

VOLT

crobar

3.8.1

Detailed

input

from

and

the

depending

resistor

circuit

comprising

circuit

E1,

capacitor

Figure

H770

3-16

regulator

E1.

Voyr

(pPin

applied

current

through

the

current

the

that

flow

overall

the

and

the

delay

failure.

precision

circuit

amplifier,

and

transistor
and

current

error

limiter;

voltage

controls

subsequently

controls

transistors

pre-drivers;

PWR20/3-67

The

circuit.

shifter.

voltage

comprises

application.

other

are

integrated

obtain

power

reference

this

regulator
Q5

Vdc,

regulator.

transistor,

power

the

Circuit

diagram

power

(24-40

monolithic

used

Vac

rectified

regulated

voltage

20-30

capacitor

and

event

transistor,

and

remote

overcurrent

the

Supply

filter

voltage

through

circuit.

voltage

integrated

used

voltage

pass-transistor;

Regulator

DEC723

base

voltage

uF)

simplified

not

precision

series-pass
10)

(31,000

This

Maintenance

includes

crobar

Power

across

through

temperature-compensated

amplifier,

H7420

and

Field

(D-CS-5411207-0-1),

provide

the

Description

This

+15

R1.

which

circuit,

overvoltage

voltage)

bleeder

3.8.1.1

Circuit

line

shown

regulator

associated

bridge

approximately

schematic

full-wave

Filter

D-CS-5411207-0-1)

circuit,

circuit

shown

circuit

(drawing

sensing

REGULATOR

Regulator

Set

on/off

+15

(03

1is

and

through

1is

the

Q6)

level

FREQUENCY

T“3)

(12)

INVERTING _ ‘4)
INPUT

COMPENSATION

(6)

(n)

ERROR

VREF ©URE

AMPLIFIER

TEMPERAT

COMPENSATED /&
ZENER

SERIES PASS

)

TRANSISTOR

VOLTAGE

(10)

REFERENCE

1 p— o v ouT

AMPLIFIER

A
9
(9

NONINVERTING (5)

CURRENT

LIMITER

INPUT

{(Part no. 1910415)

(3)

(2)

CURRENT CURRENT

V-

LIMIT

SENSE

10-1976

Figure

3-16

H770 Precision Voltage Regulator E1,
Simplified

Diagram

PWR20/3-68

Transistor

application
System

has

Zener

five

This

necessary

that

required

Q3
L@

Transistor
A

ground

and

still

provides

output

turning

diode

shuts

off,

the

raw

only

after

Control

+15

However,

across

the

input

cooling

The

voltage

+15

Vdc

ability

drawing

current

down

fans

from

this

input
of

well

input

the

2040

for

derived

most

the

collector/emitter

turn-on

which,

held

off

J1-3/J1-5.

open

+15

applied

the

H770

regulators

make

used

off

for

L1,

thus

remote

appears

choke

E1.

controls

ensures

circuitry

components

this
on,

Power

on;

switching
D3,

863

off,

(i.e.,

output

the

that

switch

Q6.

above

pass

through

the

With

turns

operate.

off

off.

retaining

turns

removed

diode

J1-1

most

E1.

turns

because

regulated

The

absorbed

for

while

transistor
emitter

1is

transistor

seconds;

passed

supplied

(5)

When

voltage

Vdc

energized

speed.

diode

switching

+15

been

approximately
are

and
the

J1-1),

and

output

providing

the
a

When

the

output

path

PWR20/3-69

+15

Vvdc
signal

resulting

J1-3/J1-5.

standard

for

"free-wheeling"
C8

and

filter.

both

on,

pins

circuit.

crobar

turned

capacitors

decay

turns

and

Regulator

emitter

crobar

turn,

consists

regulator

clamp

the

for

to
L1.

C9.

These

Free-wheeling

ground

when

In operation,

generating a sgquare-wave

is turned on and off,

voltage which is applied across D3 at the input of the LC filter
This type circuit is basically an averaging

(L1, C8 and C9).
device

square-wave voltage

and the

the output

(average)

average

By varying Q3 conduction

voltage at the output perminals.

period,

appears

voltage may be varied or

controlled, thus supplying regulation. The output voltage 1is
sensed and fed back to E1, where it is compared with a fixed
reference voltage. E1

turns pass transistor Q2 on and off,

according to whether the output voltage level decreases or

increases. Defined upper and lower limits

(see Figure 3-17)

for the output are approximately +15.45 vVdc and +14.55 Vdc
(i.e.,

+15 vdc *3%).

During one

full operation cycle,

the

regulator operates as

follows: Q3 is turned on and a high voltage
+30 Vdc)

is applied across L1.

+15 vVdc level,

(approximately

If the output 1is already at a

then a constant +15 Vdc is present across L1.

At the same time, C8 and C9 absorb this changing current and
voltage,

causing the output level

increase. When the output

(+15 V at this point)

(which is monitored by E1)

approximately +15.45 Vdc, E1

reaches

shuts off, turning Q3 off; the

emitter of 03 is clamped to ground.

current then decays

through D3, which becomes forward biased by the back emf of L1.
Pre-drivers Q4 and Q5 are used to increase the effective gain

of 03 to ensure that Q3 can be turned on and off in a relatively
short

period

time.

PWR20/3-70

Q3 OFF
_______

— _REGULATED

[

OUTPUT

+14.55v

ov
10-2235

Figure

3-17

H770

Regulator

PWR20/3-71

Waveforms

Conversely,

when

decrease,

reached,

again,

causing

superimposed
maximum

values

When

when

E1.

+14.55

also

1is

H770

overcurrent

R20

through

Q@1

normally

amperes,

(0.03

ohms)

charging.

anode

gate

Q9,

transistor
required
25

amperes

protected.

turns
off.

ensure

Thus,
that

the

regulator

on.

+14.45

Vdc

conduct

Thus,

ripple

detected

minimum

the

consists

(+14.55

turns
This

type

(PUT)

across

Q1,

Q9,

and

C4.

turn

potential

biased

output
output

and

the

Vvdc)

off
of

and
circuit

on,

the

continues

causing

voltage

regulator

resistor

voltage

which

exceeds

(present

off,

at
at

turns

the

maintained

oscillate

the

pass

decreased

RS,

Transistor

sensing

fixed

current

through

output

current

programmed

the

(approximately)

The

and

however,

charges

on.

and

begins

regulator."

UJT

voltage

Sensing

sufficient

equal

operation.

turns

circuit

causes

reached,

"ripple

output

approximately

This

Vdc)

the

output

conducting;

When

Q9)

(+15.45

forward

1is

begin

PUT

the

Programmable

not

the

sensing

R22,

value

cycle

Overcurrent

The

and

on.

+15.45

off

turn

reached,

referred

3.8.1.2

another

predetermined
by

turned

predetermined

beginning

voltage

1is

below

"short-circuit"

this

new

mode until the overload condition is'removed. Capacitor C4
then

discharges

cycle

repeats.

until

again

allowed

PWR20/3-72

turn

on,

and

the

3.8.1.3
The

H770

overvcltage

components:

and

crobar

Zener

normal

ground

small

circuit

diode

D5,

conditions,

because

cause

approximately

the

Circuit

consists

SCR

+18.6

D4,

D12,

the

following

R13,

R14,

(through

current

When

emitter-base

the

begins

across

R14.

turning

turn

remains

on.
on

Q07

The

across

Zener

diode

+15

output

the

diode

+18.6

gate

current

the

capacitors

the

conducts

R15,

SCR

forward

(D4)

1is

too

line

(D12

emitter

continues

becomes

The

R13)

current.

shorts

Vdec.

resistor

pass

SCR

until

junction

and

draws

input

Zener

sensing

trigger

voltage

Vdc,

the

base

the

conduct.

clamping

SCR

Crobar

Q7.

Under

Overvoltage

also),
Q7

rise.

biased,

voltage

drop

created

and

triggers

the

SCR

(D4),

+15

PWR20/3-73

and

line
C9

ground.

discharge.

The

H760

POWER

the H760 Power

Two models of
1.

H760A -

H760B

Basically,
models

SUPPLY

Supply

are

available:

120 Vac,

3-phase

Vac,

3-phase

240

two main

differences

between

two

the

supply

power

exist:
H760B

H760A

Diode
208

assembly

Vac

phase

obtain

fans

from phase

and

T2 and T3

have connections at input
1

from

Vac

obtain

fans

phase

and

lines.

Primary windings of

terminals

240

assembly

neutral

lines.

transformers T1,

Diode

transformers T1,

T2 and T3

have connections at input
terminals

and 2.

jumper
2

and

and 4,

between

plus a

terminals

The H760A and H760B Power Supply schematics are shown in the
Field Maintenance Print Set
D-CS-H760B-0-1,

(drawings D-CS-H760A-0-1

respectively).

and

The following paragraphs

reference those schematics and some additional simplified
drawings.

3.9.1

Detailed Circuit Description

Ferroresonant transformers are used to regulate changes in line
voltage.

PWR20/3-74

The

the

transformer

primaries

are

outputs

wired

3-phase

are

Figure

3-18).

The

Square

waves,

which

change

load

(7009878)

The

H760A

then

208

H760A

the

diode

the

eénergy

(208

the

due

With

vdc

when

Vdc

distribution

CPU

and

Primary

and

aiso

phase

cabinet.

the

240
and
CPU

the

Vac

H760B,

J1-2);

240

Vac

applied

the

fans

and

Vac

240

applied

power

diode

uF,

cabinet.

PWR20/3-75

the

30%)

the

1is

removed.

fans

120

assembly

That

diode

and

filter

respectively).

vac

CPU

1is

provided

input

120

the

H760A

supply

power

the

(+10%

vac,

fans

the
60

Hz,

the

identical

J1-1
is

and

cabinet

the

In the case

assembl!y

ceiling

J1-2)

applied

ceiling fans in the CéU cabinet
via J1-3 and J1-7.
of

power

(through

Only

essentially

the

lines.

(see

Assembly

input

power

are

line

30,000

applied

operation

while

Capacitor

outputs

the

applied

the

delta,

Outputs

output,

(50,000

3-phase

rectified.

holdup

the

full-wave

volts

+15

transformers

phase

Vac)

-11

the

When

power

the

fans

for

shows

Vac

the

variations.

and

H760B.

from

voltage

3-19
and

are

holdup

capacitors

Figure

100%)

added

outputs

approxmiatel
1.5
y

(25%

capable

for

wired

fans;

(through
fans

J1-1

the

£1o

-12vDC

@ 490A

£
112

A
T2

)

(@ 4A
+15V

4 3

RTN

=
D4

}E
-1sv(@ 2A

Lind

D13

RTN

D16

D10
3

D15

D17

<
<

¢ 7

D18

D12
10-186%5

Figure

3-18

H760A Power Supply,

Simplified Schematic

H760A

H7608
DIODE
ASSEMBLY
FANS

120 X /3 =208VAC

DIODE
ASSEMBLY
FANS

I 240 x /

= 415VAC

)

._I 120VAC

¢C
N

J 240VAC
(CONNECTIONS

J1
J1

r—
[ros—

o
H76!1

COOLING
FANS

T0O

FANS

CABINET

FLUSHING

S‘UPPIJED)

!
2

CPU

COOLING
ASSY

’

FANS || 7

o~
10-1969

Figure

3-19

Distribution

Power

PWR20/3-77

Fans

H760A

and

H760B

3.10

CAPACITOR ASSEMBLY

The Capacitor Assembly is shown in the Field Maintenance Print
Set (E-AD-7009878-0-0 and D-CS-7009475-0-1). The following
paragraphs reference the circuit schematic.

3.10.1

Detailed Circuit Schematic

The Capacitor Assembly is connected between the H760 Power
Ssupply and the H761 Series Pass Assembly. Thirteen (13)0.3

Farad capacitors are connected in parallel to achieve an
overall capacitance of 3.9 Farads. The output voltage under

full load is approximately -11 Vvdc *10% when the assembly is

connected to the H761. When the input voltage to the Capacitor
Assembly drops below this value (e.g., during normal shut-down
or a power failure), the capacitors discharge exponentially

through the parallel resistance load, which is only a fraction
of an ohm (see Figure 3-20). A delay of 20 ms is thus

obtained before the discharge voltage decays to a value of
about -7.5 Vdc. During this 20 ms period, critical information
may be appropriately stored in memory for reuse after power

j00)

restoration.

VOLTS

-12vDC

—

—_—

—

=10.5vDC

!
!
|
!

|
|

_+zo

Msec

TIME —e»
10-1866

Figure

3-20

Capacitor

PWR20/3-79

Discharge

Curve

The

function

-11

Vdc

input

ASSEMBLY

PASS

SERIES

H761

3.11

the

from

H761
the

H760

(D-CS-7009475-0-1)

into

regulated

outputs

include

negative

(9)

Figure

shown

The

-5.2

Vdc

the

-5.2

nine

-2.0

Detailed

The

Series

H761

the

Capacitor

(13)

the

lines

are

unregulated,

CPU.

highly

These

outputs

Vdc

=-2.0

(4)

four

single

Assembly

separate,

2040

and

labelled
are

Circuit

Pass

Quantity

and

thirteen

Vdc

outputs

3.11.1

convert

lines,

3-21.

outputs
Vdc

labelled

and

Description

Assembly

comprises

six

subassemblies:

Subassembly

Name

G8013

+10

G8010

-5.2

G8011

Reference

(Quad)

Control

(Triple)

-2.0

Control

(Triple)

7009405

-5.2

V Heat

Sink

Ass'y

(Quad)

7009404

-2.0

Sink

Ass'y

(Dual)

G8014

DC Low Vbltage Detector

The Y15 Vdc
Reference

from the H760 Power Supply is

and to

The

-12

Vdc

and

-2.0

from
Heat

all of
the

the

-5.2 V and

Capacitor

Assembly

Sink.

PWR20/3-80

Heat

input to the +10 V

-2.0 V Control
is

input

Circuits.

each

-5.2

[

—2.001

]

—z.oTl

I
(NOT USED) —f

-208

L8-€/02dMd

-5.2 Jw

15y

+10 v

(+10V)
_REF

INHIBIT

LOW VOLTAGE
DETECTOR

(68014)

SENSE '03

RTN

—

[

SENSE

310

Ll I el

-5.241

-5.20

-5.2¢C

OVER-

_____

LOAD

TERMINAL

BOARD

r—--- ,
:'
E

HEAT SINK
70094

SCR (GATE)

(7009405)

]

1
-12V RTN
r

H761

Lyt ]

VOLTAGE

|-——( NOT USED)

-5.2 fl
-5.2F |

-52 A

DRIVE

~ ~-

-5.2k

528 l

CONTROL

RTN—s] REFERENCE | \gTn)
(68010)
-15v
(coon3)
+—15V —o OPEN
—
::
-2.0v

-5.2¢

5.2 91

2.0A

-5.2 E ]

[

-5.2 A
-5.2V

{

-5.2L

-5.2 € 1

-5.2 D |

[

5.2 H
-5.2 F]

[

(7009404)

-5.2K ]

[

HEAT SINK

~-572q

[

-20¢C

-2.0B

e EB
]
-2.0v CONTROL (G8011) _20A ]

[

-2.00

{

-52V
L
=

1
CIRCUIT

| SCR
IRTN
!
l

BREAKER

TRIPPED

-5.2V SENSE

-5.2v 2VOP OPEN SENSE

4
i

| -

SCR RTN

10-186
4

Figure

3-21

H761

Regulated

Simplified

Series

Diagram

Pass

Assembly,

+10

-2.0

V
V

reference
Control.

voltage

The

labelled YREF

1is

supplied

each

voltage

the

reference

the

one

the

-5.2
-5.2

V
V

=-2.0 V Controls

and
Controls

labelled IREF C.

The
an

outputs
SCR

gate,

each

which

control
are

circuit

applied

comprise

each

heat

sink

applied

lines

are

tied

from

the

load

back

the

detector

1is

present

circuit
"open

overvoltage

that

sense"

and

its

the

sense

lines

associated
and

lines

event

sense

Direct
the

+10

that

from

3.11.1.1

Two

the

-2.0

with

the

broken

are

made

This

identical

the

are

sink.

and

each

heat

ohm

the

regulators
at

voltage

the

sense"

detector.

fed

inhibit

back

signal

and

off

Control
set

sink

the

The

Because

-2.0

resistor

"open

(load).
V

purpose

-2.0

of
output

separates
"open
in

sense"”

the

load.

lines
A
to

single
the

which

the

+10

ensures

proper

regulators.

utilized

the

2040

system configuration,

the

-2.0

the

heat

and

(G8013)

with outputs

Controls;

turned

-5.2

Reference

signal

lines.

each

detector

are

-5.2

disconnected

low

voltage

CPU

sense

The

and

output

circuits

Reference board,

the

between

the

regulators

respect

+10

low

the

lines.

-5.2

and

circuit.

sense"

controls

Reference.

the

time,

connected

Control

protect
line

directly

"open

connections

-5.2

output

tied

drive

associated

output

Controls,

*TREF

the

G8013

labelled *REF

and *REF

the *REF C output is
B

output

controls.

PWR20/3-82

applied

applied to
the

=-5.2

Consider

the

Figure

3-22.

appears

operation

The

both

input

6.2

because

decreases,

causing

Vdc,

the

reference

necessary

=5.2

+10

that

applied

the

Q6.

reference
Q6

the

-2.0

+10

inhibit

line

always

turned

(See

+6.2

when

+6.2

Q@1

the

and

the

differential

voltage

the

output

conduct,

thereby

reference

voltage

reference

and

-2.0

increases

result,

control

before

-5.2

the

above
causes

6.2

line

Zener,

about

off

and

The

the

grounded,
Section

0.5

PWR20/3-83

after

regulators.

which

effectively

When

This

bringing

the

inhibit

reference

1is

*REF

circuit,

which

Controls,

that

the

for

the

-5.2

the

controls

activated,

Volt.

+10

3.11.1.6

operation).

line

and

the

voltages,

turned

inhibit

reference

off.

causes

Controls.

permanently

+6.2

shown

when

the

regulators

output

reference

-5.2

the

turned

Vdc

Volts).

increasing

the

off

the

+10

level.

means

When

circuit,

(i.e.,

below

above

and

the

and

zero

the

goes

-2.0

This

diode.

more,

desired

clamping

furnishes

inhibit

on,

removed,

drops

sequence

and

voltage

accomplished

turned

the

regulators

operation

*REF

output

Zener

conduct

the

properly

positive.

decrease

pins

the

goes

+10

reference

pulling

the

approximately

(pin

and

has

its

equivalent
details

1is

+15

$1.5k
<

$10K
<

©+REF C

$sn
)

$511
)

2700t
1

3 +
1;

$15K

2003«

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-_T
4

-15

INHIBIT C o—1

8 6

| 1n825

¥ 6.2v

+15

315K
o —REF
C
10- 1063

Figure 3-22

+10 V Reference, Simplified Schematic of *REF C Circuit

PWR20/3-84

3.11.1.2

-5.2

Referring

three

Vdc

Controls

drawing

identical

D-C5-G8010-0-1,

circuits

subassemblies

provide

necessary

2040

and

for

(G8010)

the

each

nine

operation.

overvoltage

Figure

3-23,

the

-5.2

point

+10

Vdc,

while

the

10K

because

goes

the

output

and

+SENSE

decreasing

the

current

through

associated

heat

sink.

current

regulator

such

circuits

includes

Vdc

Control

Circuit.

The

and

-SENSE

the

increases

the

Q1,

which

regulator

through

-5.2

effect

the

-5.2

negative,

and

the

less

with

Vdc.

ground

conduct

+REF

dividing

goes

decreases

grounded.

voltage

are

causes

-5.2

point

the

goes

current

of
Pin

This

drive

Three

are

circuit

points

follows.

occurs,

there

Each

because

reverse

subassembly.

-5.2

resistors.

and

negative,

(pin

Vdc

5.2K

-REF

that

detector.

Refer

notice

less,

drive

thereby

for

negative,

the

increases.

Thus,

fluctuations

the

load.

Overvoltage

detection

inadvertent

short

lines.

the

-0.

provided

circuit

(Minus

protect

against

negative

supply

Overvoltage)

point

goes

the

negative, the base of Q9 goes moré negative, turning it on.
The

gate

the

SCR

positive

and

lines

approximately

the

current

breaker

turns

through
the

H761

the

associated

SCR,

-1.5

heat

thereby

Volts.

removed

the

The
by

supply

PWR20/3-85

sink

clamping

SCR

goes

the

remains

tripping

shorted

-5.2

until

circuit
it.

-5.2

DRIVE

+REF

(+10V)

100

- REF

i€

M-

€l
3]

SENSE,
B

+15v

+i15Vv

10
e

220

OPEN

352k

52K3
-

-15V

3 10k

10K $

0.01ut

(RTN)

A A sammmJ

+ OVERVOLTAGE (+0V.)

osGE>
+

)

3903

032

SENSE
RTN

268
3

¥s

AV
SCR

-5.2V

- OVERVOLTAGE (- 0.V.)

(GATE)
10-1862

Figure

3-23

Typical

G8010

Simplified

-5.2

Vdc

Schematic

PWR20/3-86

Control

Circuit,

The

LED

the

indication

that

determining

long

the
or

sense

V),

ohm

which

supply

module

resistor

are

disconnected,

3.11.1.3

identical

regulator

the

Vdc

circuits

3-24,

point

at
is

10K

and

regulator

negative,

the

has

also
no

aids

output.

output,

the

LED

the

each

maximum

prevent

the

sense

lead

supply

only

and

voltage

this,

leads

and

broken

increases

Vdc,

while

the

Vdc

because

are

goes

remain

2040

Vdc

the

grounded.

at
the

negative,

follows.

PWR20/3-87

such

unused)

=-2.0

Each

Circuit.

point

are

circuit

detector.

voltage

there

Two

operation.

Control

-SENSE

that

subassembly.

overvoltage

-2.0

points

notice

(some

for

the

each

(G8011)

four

resistors.

+SENSE

goes

circuit.

Thus,

necessary

Figure

output

D-CS-G8011-0-1,

provide

+10

sink.

circuits

associated

the

Controls

Refer

(pin

the

mV.

-REF

provides

voltage.

regulator

between

output

includes

the

D3)

which

open,

added

drawing

subassemblies

and

(diode

output

overvoltage

heat

300

-2.0

Referring

the

approximately

has

present

leads

tripping

output

three

circuit

on.

the

(=11

the

voltage

remains

overvoltage

The

-2.0

+REF
vdc.

dividing

effect

ground

because

the

-2.0

goes

and

the

output

DRIVE

+ REF

(+10V)

- REF

0.01uf

(RTN)

)4
1

3l
4

AA r—

&
+15v

-15V

+15V

3 2k

2K 3
10

OPEN — "W

SENSE,

3 10k

10K $

A A A et
e

+ OVERVOLTAGE (+0V.)

osGE>

SENSE
RTN

<€

368

68
3

¥ 2av
SCR

(GATE)

-2.0v

- OVERVOLTAGE (- O.V.)
10-2234

Figure

3-24

Typical

G8011

-2.0

Vdc
v

Simplified

Schematic

PWR20/3-88

Control

Circuit,

This

causes

through

the

Q17,

-2.0

current

conduct

which

goes

with

negative,

on.

The

gate

negative,

the

reverse

the

-0.

SCR

the

lines

approximately

the

current

breaker

the

that

which

through
the

H761

overvoltage

the

supply

module

continually

on,

-1.5

the

negative,

voltage

heat

SCR

the
increases

shorted

provides

also

the
goes

sink

goes

the

-2.0

until

circuit
it.

aids

output.

present

turning

remains

tripping

D3)

has

point

clamping

The

voltage.

regulator

long

supply

(diode

current

negative

sink.

and

against

thereby

removed

heat

protect

associated

output

drive

current

load.

Volts.

the

occurs,

Overvoltage)

goes

which
as

SCR,

circuit

has

and

the

(Minus

and

base

positive

turns

associated

the

provided

circuit

the

short

lines.

for

fluctuations

inadvertent

decreasing

drive

Thus,

detection

thereby

increases.

Overvoltage

-~2.0

the

less

through

decreases

less,

The

indication
in

determining

The

LED

the

associated

output.

the

(=11
10

sense

V),

ohm

output

tripping

resistor
of

the

disconnected,

300

leads

are

the

open,

the

output

overvoltage

added

between

heat

sink.

Thus,

the

output

the

circuit.
each

goes

sense

supply

mvV.

PWR20/3-89

the

maximum

prevent
sense

lead

increases

voltage

this,

leads

and

broken,

a
the

approximately

V Heat

-5.2

3.11.1.4

identical

other

shown

circuits

is,

causes the -V.0.
a

The

limit
the

current
less;

limiting

in Q2

thus,

rating of
breaker

the

trips,

the

current

the

-V.O0.

Q2.

the

clamping
power

1is

-v.0.

the

internal

shuts off power to

(D1)

output to

1is

-1.5 Vdc.

removed.

two

steps.

a point which

circuit breaker,

SCR

The main current

the breaker

110%

-11
to

trips.

switch in the breaker

sending a ground signal to the 863 Power Control.
signal

the

Regulation

is performed

the

causes

output to go more negative.

until

increases

1is

in current

is provided by a circuit breaker in the

current

circuit

an increase

Conversely,

function of

effectively

SCR remains

Current

Assembly.

an overvoltage condition,

In the event of
turned on,

conduct

Four

a power Darlington amplifier with

A decrease

transistors

therefore,

overall

the associated -5.2 V Control

which forms

and Q6.

the

comprise

output goes more positive.

in Q2

3-25.

(D-CS-7009405-0~1)

Q5,

four

in Figure

the

applied to Q2,
Q4,

Sink

schematic of

The drive output of

Q3,

-5.2 V Heat

one

A simplified
Assemblies

Sink Assembly

V line.
125%

PWR20/3-90

the

When the
closes,

This ground

the H760 Power Supply and

H761.

consequently

r——_—f

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-12v

rar |

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220
SCR RTN
10-186¢

Figure

3-25

Typical

-5.2

Heat

Sink,

PWR20/3-91

Simplified

Schematic

The circuit breaker is a magnetic mechanical device and

(trip time at 500% of rating is

therefore is relatively slow

trip under short-circuit

be damaged.

Therefore,

ohm resistors,

The 5.1

During the time that the circuit breaker needs to

10 ms).

conditions,

the transistors could

a faster current limiter is needed.
12 ohm resistors,

and Q1

form this

circuit.

Current drawn by the Darlington is sensed through the 0.07
ohm resistors and then summed by the 5.1 ohm resistors. When
the voltage across the 0.07 ohm resistors is above the Vpe at

01, Q01

conducts, decreasing the base drive to Q2. This causes

03, 94, Q5, and Q6 to conduct less, achieving current limiting.
The circuit breaker is the main current limiter, while the
transistor circuit provides transient current limiting.

The

0.07 ohm resistors are current sensors and also ensure better
Q5,

and Q6.

sharing of current among Q3,

Q4,

The series combination of C1

and R17 minimizes parasitics;
filters.

are

networks C2/R19 and C6/R30

-2.0 V Heat Sink Assembly

3.11.1.5

A simplified schematic of one of the -2.0 V Heat Sink Assemblies
is shown in Figure 3-26. Two identical

(D-CS-7009494-0-1)
circuits

comprise

the overall Assembly.

The drive output of the associated -2.0 V Control circuit is
applied to Q2, which forms a power Darlington amplifier with
Q3,

Q4,

Q5,

Qo,

Q7,

and Q8.

PWR20/3-92

r--=9

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DRIVE o—

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—{]-v.0. (-2.0vdc)

ToOot

SCR.

(GATE)

347

3rR19

kD1

322

JLc3

220
—oSCR RTN
10-1859

Figure

3-26

Typical

Simplified

-2.0

Vdc

Schematic

Heat

Sink,

The

circuit

except

for

the

essentially

the

same

addition

two

transistors

power-dissipation

the
in

transistors
the

the

-5.2

other

output
in
is,

In
on,

causes

the

therefore,

event

Current

limiting

the

rating

trips,

sending

ground

signal

consequently

circuit

relatively
the

slow

short-circuit

the

conditions,

faster

resistors,

ohm

placed

thus,

Sink,

for
across

(5)

volts

causes

the

-V.O0.

increase

negative.

current

Regulation

Q2.

the

SCR

(D1)

1is

turned

-1.5

Vdc.

The

SCR

two

the

steps.

which

the

863
to

-11

110%

125%

trips.

When

the

H760

breaker

Control.
Power

current

the

Power

the

main

breaker
in

The

line.

If
the

closes,

This

Supply

and

H761.

that

Q8)

output

switch

power

(trip

Therefore,

and

current

breaker

point

off

breaker

time

breaker,

signal

the

circuit
to

(Q7

five

condition,

-V.0.

Heat

removed.

internal

shuts
to

The

During

the

performed

circuit

breaker

ground

versus

less;

current

overvoltage

increases

the

Conversely,
to

-5.2

volts

conduct

output

power

provided

decrease

function

until

current

clamping

-V.0.

(8)

the

configuration,

Sink.

remains

Eight

positive.

effectively

limit

this

transistors

goes

the

purposes.

Heat

six

magnetic

time

circuit
the

current

resistors,

mechanical

500%

breaker

transistors

limiter
and

PWR20/3-94

device

rating
needs

form

could

needed.
this

The

and

10
trip

therefore

ms).
under

damaged.

5.1

circuit.

ohm

Current

drawn

resistors
voltage
Q1

Q5,

the

and

then

across

the

conducts,

Q4,

Q6,

summed
0.1

Q7,

and

while

transistor

ensure

circuit

The

0.1

better

and

Q8.

The

series

3.11.1.6

The

G8014

Maintenance
paragraphs

The

-2.0

Low

Detector

circuit

will

turned

before

outputs

are

board

the

are

allowed

are

allowed

+10

V
on

-5.2

accomplished

they

limiter,

sensors
Q5,

and
Q6,

also
07,

parasitics:

The

the

Field

following

schematic.

regulators

off

causes

current

Q4,

shown

(D-CS-G8014-0-1).
the

91,

(G8014)

the

and

Q3,

the

filters.

When

detector

are

current

ohm

current

minimizes

LOW)

outputs.

-2.0

R13

the

and

this

segquencing

achieving

0.1

When

Vpe

This

transient

among

the

Q2.

main

provides

current

above
to

less,

are

through

resistors.

the

regulators,

-5.2

Voltage

function

resistors

Voltage

Set

ohm

drive

conduct

C3/R19

reference

(labelled

Vdc

Power

Low

primary

signal

ohm

and

sensed

5.1

base

circuit

combination

C2/R15

the

breaker

sharing

networks

the

Q8
. to

The

limiting.

ohm resistors

decreasing

limiting.
the

Darlington

provide

after

-5.2

Vdc

the

that

the

Vdc

regulators.

sensing

the

negative

turn

on.

PWR20/3-95

inhibit

Reference

all

float.

level

than

-4.75

Unused

inputs

the

v,
the

-5.2

comparator E2 goes

into

tied

turning

off

Reference

and

regulators.
until

the

-4.75 Vdc.
the

output

positive

than

low and turns Q1

off.

goes

V output

the base

detector

the

shuts

down

When power

=-5.2 Vdc

circuit of Q11

turns

the

Q11

the

in Figure

3-22.

the +10

for

-2.0 Vdc

the

negative

in the detector

are all more

output

The collector of

+10 V reference

applied,

regulators

-4.75

is off

than

s oscillation in
‘any
Internal hysteresis eliminate
of

the

comparator.

Supply voltages of +11

Vdc and -6.2 Vdc
D5,

D6,

for operation of E2

and D7

on the

detector

and Q1

are provided by diodes

board.

The Y15 V input to the diodes comes from the H760 Power

Supply.

PWR20/3-96

3.12

AIR

The

2040

FLOW

System

approximately

diameter.

the

CPU

SENSORS

and

air-flow

air

3-1/2

They
I/0

3.27.

Sensing

inches

are

accomplished
module

the

head

temperature

several

small

change

self

cooled

until

heat.

air

reduced,

begins

increase.

reaches

This

the

rapid

used

flow,

stability

long

that

sensor

are

protective

has

low

resistance

point,

for

applied

cooling

air

remains

both

and
in

housing

critical

this

voltage

cm)

temperature

shown

reaches

(1.27

diagram

magnitude

inch

switches

locations

wiring

positive

curve.
of

1/2

vane

its

point

the

resistance

correspondingly
across

flows,
stable

the
at

causes

sensor

its

low

point.

normal

cooling

temperature.

sufficiently

resistance

Below

wvarious

typical

sensor

orders

long

mounted

temperature/resistance

changes

using

This

increases,

cm)

solid-state

simplified

sensor

probe.

(8.9

are

positioned

cabinets.

coefficient

sensors

characteristics

Figure

its

flow

less

and

trigger

and

point,

gate

the

elevated
and

subsequent

efficient

disturbed,

critical

rise

damage

equipment
heat

transfer

sensor

module

temperature,

resistance

current

the

863

PWR20/3-97

can

causes

With

the

temperature

the

increases

reduction

Power

result.

Control.

module
sharply.

sensed

and

DEVICE

SOLID
STATE

AIR FLOW
SENSING

POWER
SUPPLY
—

SECTION

SWITCH

A. SIMPLIFIED WIRING DIAGRAM

170

160
140

v 130
W

TRIP

REGTON

120

115._.-_-._.4-—.

§§
—

e v | —

—f —

510

100

REG

60
50

100

300

S00

700

100

900

L. FT/MIN
VELOCITY

8. AIR FLOW VERSUS TEMPERATURE
10-1860

Figure

3-27

Air

Flow

Sensor

PWR20/3-98

Characteristics

shown

left

Figure

3-27

the

dashed

curve,

region

sensor

will

and

the

500

air

the

right

indicate

flow

(b),

the

"tripping"

and

the

dashed

problem

region

"non-tripping"
curve.

the

200

feet/minute.

feet/minute,

the

sensor

will

PWR20/3-99

For

not

indicate

the

"hold"

example,

temperature

However,

1000

air

fault.

the

flow

Reader’s Comments
DECSYSTEM-20 POWER SYSTEM
SYSTEM DESCRIPTION
EK-PWR20-SD-001

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