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Maynard, Massachusetts

aintenanc

P
P
R

anual

4/PC05
ER-TAP
DER/PU

(FEED-HOLE STROBED M

DEC-OOPCOA-D( 1)

PC04/PCO5
PAPER-TAPE
READER/PUNCH
(FEED-HOLE STROBED MODELS)

This manual pertains only to those PC04 or PC05 models that
strobe the data by the signal derived from the feed holes. This
method is provided when ECO number PCO4-00046 or P C 0 5
00021 is implemented on the corresponding PC04 or PC05 unit.
When the unit is not implemented with the above ECO, refer
instead to the corresponding maintenance manual:

PC04 (Document Number DEC-00-HGPA-D) or
PC05 (Document Number DEC-00-HGHA-D).

DIGITAL EQUIPMENT CORPORATION

MAYNARD, MASSACHUSETTS

1st Edition, August 1970
2nd Printing (Rev) June 197 1
3rd Printing October 1972
4th Printing December 1972

The material in this manual is for informational purposes and is subject to change without
notice.

The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
DEC
FLIP CHIP
DIGITAL

PDP
FOCAL
COMPUTER LAB

CONTENTS

Page
CHAPTER 1 GENERAL INFORMATION

1.1
1.2
1.3
1.3.1
1.3.2
1.4

1-1
1-1
1-2
1-2
1-3
1-3

Scope
General Description
Functional Description
Reader
Punch
Specifications

CHAPTER 2 INSTALLATION
2.1
2.2
2.2.1
2.2.2
2.2.3
2.3
2.4

2-1
2-1
2-1
2-1
2-2
2-3
2-3

Inspection
Installation
Mounting
Connections
Module Configurations
Power Requirements
Checkout

CHAPTER 3 OPERATION
3.1
3.2
3.3

3.3.1
3.3.2

3-1
3-1
3-1
3-1
3-3

Introduction
Controls and Fuses
Operating Instructions
Loading Blank Tape
Loading Prepunched Tape

CHAPTER 4 PRINCIPLES OF OPERATION
4.1
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.2
4.2.1
4.2.2

4-1
4-1
4-2
4-3
4-3
4-3
4-3
4-3
4-4

Paper-Tape Reader
Tape Feed Operation
Tape Reading
Tape Reader Control
Out-of-Tape
Strobe
Paper-Tape Punch
Feed Control
Tape Punch Control

CHAPTER 5 MAINTENANCE
5.1
5.2
5.2.1
5.2.1.1
5.2.1.2
5.3

Introduction
Preventive Maintenance
Preventive Maintenance Procedures
Mechanical Checks
Electrical Checks
PCO4/PCO5 Reader Adjustments (Feed-Hole Strobed Models)

5-1
5-1
5-2
5-2
5-2

5.3.1

Introduction

5-2
...

ll1

5-2

CONTENTS (Cont)
Page
5.3.2
5.3.3
5.3.4
5.3.5
5.3.6
5.3.7
5.3.8
5.3.9
5.3. I O
5.3.1 1
5.3.1 1.1
5.3.1 1.2
5.3.1 1.3
5.3.1 1.4
5.3.1 1.5
5.3.1 1.6
5.3.1 1.7
5.4
5.4.1
5.4.2
5.4.2.1
5.4.2.2
5.4.2.3
5.4.3
5.4.4
5.4.5
5.4.5.1
5.4.5.2
5.4.6
5.4.6.1
5.4.6.2
5.4.6.3

Prcliminary Adjustments
Test Tape Registration
Feed Whccl and Motor Adjustmen
Tape Depressor
Tape Hold-Down Bracket
Lamp, Lens, and Light Pattern
Full-Speed Running Rate
Acceleration and Stop Delay
Threshold and Skew
Testing and Error Correction
Data Bits Picked Up
Data Bits Dropped
Skipping Characters
Double Reading
Dropping Flags
Out-of-Tape Circuit
Acceptance Testing
Punch Adjustment Procedures
General
Tape Output Quality
Sprocket Wheel Adjustment
Burred Feed Holes
Elongated Feed Holes
Tape Depressor
Electrical Parameters
Basic Timing
Method (1)
Method (2)
Magnet Adjustments
Pulse Generator Air Gap
Forward Index Magnet Armature Adjustment
Punch Magnet Adjustment

5-3
5-4
5-4
5-5
5-5
5-6
5-6
5-8
5-9
5-1 0
5-10
5-1 1
5-1 1
5-1 1
5-1 1
5-1 1
5-1 1
5-1 1
5-1 1
5-1 1

5-1 2
5-1 2
5-1 2
5-13
5-13
5-15
5-1 5
5-16
5-1 6

5-16
5-1 6
5-1 7

CHAPTER 6 REFERENCE DRAWING LIST
APPENDIX A DIAGNOSTIC PROGRAMS
APPENDIX B SUGGESTED PROGRAMS FOR ALTERNATE ONES AND ZEROS TEST ‘TAPES
APPENDIX C STALL PROGRAMS
APPENDIX D SUMMARY SET-UP PROCEDURE

ILLUSTRATIONS
Figure No.
1-1

1-2
2- 1
3- 1
3-2

4-1

4-2
5- 1
5-2
5-3
5 -4
5-5
5-6
5-7
5-8
5-9
5-1 0
5-1 1
5-1 2
5-1 3
5-14
5-1 5

Title
Reader Functional Block Diagram
Punch Functional Block Diagram
PCO4/PCO5 Module Locations
Paper Tape Path, Top View
Installing Tapc in Paper-Tape Reader
Tape Feed Operation
Simplified Block Diagram, Punch Operation
Regulator Board
Feed Wheel and Motor Adjustment
Tape Depressor
Tape Hold-Down Bracket
PCO4/PCO5, Rear View
Light Pattern
M040 Input and Output Waveforms
Acceleration and Stall Waveforms
Summation Waveform, G 9 18 Test Point
Specifications for I-In. Paper Tape
Improved Tape Dcpressor
Electrical Parameters
Punch Assembly
Forward Index Magnet Armature
Punch Magnet

Art No.

Page

CO-0479
C0-0480
CP-0 133

1-2
1-3
2-2
3-2
3-3
4-2
4-4
5-3
5-5

CO-0478
C0-047 1
CP-0034
C P 4 1 15
CP-0 1 16
CP-0033
CP-0 1 I 2
C P 4 1 13
CP-0 1 14
C0-0473
CO-0476
C0-0474
C0-0472
C0-0475

5-5
5-6
5-7
5-7
5-8
5-9
5-10
5-1 2
5-14
5-14
5-16
5-17
5-18

TABLES
Table No.
1-1

1-2
2- 1
2-2
3- 1

5- 1
5-2
5-3
5-4
6- 1
6-2
6-3

Title

Page

PCO4/PCO5 Configurations
PCO4/PCO5 Specifications
CPU and BA Connections
Module Configurations
PCO4/PCO5 Controls and Fuses
Required Maintenance Equipment
Power Supply Output Checks
M040 Motor Driver Input and Output Pin Locations
G9 18 Photoamplifier Pin Locations
PC04 Engineering Drawings
PC05 Engineering Drawings
PCO4/PCO5 Module Circuit Schematics

1-1
1-4
2-1
2-3
3-1
5-1
5-2
5-8
5-9
6-1
6-1
6-2

-CHAPTER 1
GENERAL INFORMATION

1.1 SCOPE

This manual contains maintenance information for both the PC04 and PC05 High-speed Paper-Tape Readers and
Punches (feed-hole strobed models only) manufactured by Digital Equipment Corporation (DEC). The earlier
versions of thc PC04 and PCOS models, which do not strobe the data by the signal derived from the feed holes,
are described in the following maintenance manuals: PC04 Maintenance Manual, DEC-00-HGPA-DIand PC05
M a i n t e n ~ / ~Matlual,
ce
DEC-00-HGHA-D.
The PC04 is currently used with the PDP-8E, PDP-81, and PDP-8L computer systems, and the PCOS is used with

the PDP-I I , PDP-1 2 , and PDP-15 computer systems. Each computer system has its own unique interface and
control characteristics; consequently, this manual discusses only the electrical and mechanical operations of the
basic reader and punch and considers the computer an external piece of equipment.

-1.2 GENERAL DESCRIPTION

The PCO4/PCOS High-speed Reader and Punch is supplied as an option to the various computer systems and is
available in the configurations listed in Table 1-1.

PC05 (Used with
PDP-11, 12, and 15)

PC04 (Used with
PDP-81)

PC04 (Used with
PDP-8E and 8L)

Reader Only

PC04R

PC04RB

PCOSR

Punch Only

PCO4P, PA*

PCO4PL, PM*

PCOSP, PA*

Reader and Punch

PC04BB, BC*

PC04BL, BM*

PCOSC, CA*

Description

1-1

The tape punch mechanism is a Roytron Model 500 modified by DEC. Contained in the unit is an electromechanical tape feed and punch system capable of punching five-, seven-, o r eight-level tape. In addition, an SCR Driver
is included on the PC05 that switches the ac power to the punch motor after a command to punch is received.

1.3 FUNCTIONAL DESCRIF’TION

1.3.1 Reader
A functional block diagram of the tape reader is shown in Figure 1-1. The read head, located below the tape,
contains nine photocells; eight for sensing data and one for sensing the feed hole.
The light source is located directly above the tape channel and read head. As the tape passes over the read head,
each photocell senses the presence (a hole) or absence (no hole) of light. When a hole is detected, tlhat photocell
is activated and feeds an individual photoamplifier. The output of the photoamplifier is sent to the M7050
Reader Control Module, which temporarily stores the eight data bits in a buffer and then signals the: central p r o 0
essor that data is available. The central processor responds with a command that strobes the data (KD holes 1
through 8) into the central processor via the Input-Output Bus lines.
The reader FEED switch, when pressed, enables the reader control, which advances the tape through the read
head without actually reading.

M040
SD

FEED HOLE
RD HOLE 8
RD HOLE 7
RD HOLE 6
RD
RD HOLE 4
RD HOLE 3
RD HOLE 2
RD HOLE 1

OUT OF TAPE
RD HOLES 1-8

M7050
READER
CONTROL
MODULE

SKIP
INTERRUPT

READER FEED SWITCH

INPUT/
OUTPUT
BUS

TO CPU

Figure 1-1 Reader Functional Block Diagram
Tape is advanced through the read station in a stepping motion by a sprocket wheel connected to the shaft of the
reader drive motor. The M040 Solenoid Driver Modules provide drive current to the two center-tapped motor
windings in turn. As each half of a winding is activated, the motor and, hence, the sprocket wheel rotate to pull
the tape through the read station.

1-2

1.3.2 Punch
The punch unit performs three basic operations: it moves the paper tape, positions the tape, and punches the tape
kloving, positioning, and punching of paper tape all occur during one rotation of the punch mainshaft.

A functional block diagram of the punch is shown in Figure 1-2. A punch command and the data t o be punched
are sent from the respective central processor and are stored in the h.1710 Punch Control Module'. When it has
been determined that the punch mainshaft is at the beginning of a punch cycle, the M7 10 activates the M044
Solenoid Interposer Drivers which, in turn, initiate operation of the punch pins. The M7 10 then signals the central processor that another punch command may be initiated.
The punch drive motor, which advances the tape through the punch block, is iontrollcd by the SCR Driver in lhe
PC05 and a switch in the PC04. The object of the SCR is t o run the motor only when punching t o eliminate unnecessary noise and wear. There are two ways of enabling the SCR Driver:
a. A punch command from the CPU.

b. Pressing the PUNCH FEED switch (overrides a punch command from the CPU).

Thc motor requires 0.4 sec to reach full speed, at which time the punch command is executed. A timer in the
punch circuitry allows the motor t o run for 5 sec after the last punch command, in the event more punching is
t o occur.
PUNCH PINS

..........'.
PUNCH
DRIVE
fiinTnD

PUNCH BLOCK
(INTERPOSERS)

1 2 3 F 4 5 6 7 8
115VAC

DATA FROM CPU

PUNCH
CONTROL
MODULE

ttt

Y
COMMANDS FROM CPU
CO-0480

Figure 1-2 Punch Functional Block Diagram
1.4 SPECIFICATIONS
Table 1-2 lists the mechanical, electrical, and environmental specifications for the PC04 and PC05 Reader/punch.

?The PCBE incorporates the M 7 0 5 0 (Reader Control), the M 7 1 5 (Reader Accelerator), and the M 7 1 0 (Punch Control) functions on one module:
the M840. Otherwise operation is identical.

1-3

Table 1-2
PCO4/PCO5 Specifications
Specification

Description

Physical dimensions

1Ieight: 10.5 in.
Width: 19 in.
Depth: 15 in.

Tape characteristics

Reader: Gray, moiled, fan-folded**
Punch: Oiled or moiled, fan-folded

Tape tension (in punch)

6 oz, maximum

Power requirements

115 Vac +lo%, 50 or 60 Hz

Power supplies (internal)

Regulated, - 1 5V f 1V
Regulated, +5V f: 0.25V
Unregulated, -36V f 4V

Logic levels

Logic 1 (H): +2.0V, input
+2.4V, output
Logic 0 (L): +0.8V, input
+0.4V, output

Temperature
(Operating)

Reader: 55" to 110°F
Punch: 55" t o 110°F

Temperature
(Nonoperdtilig)

Reader: 10" t o 150°F
Punch: 10" to 150°F

Humidity*
(Operating)

Reader: 20 t o 95% (w/o condensation)
Punch: 20 t o 95% (w/o condensation)

Humidity
(Nonoperating)

Reader: 5 t o 95% (w/o condensation)
Punch: 5 t o 95% (w/o condensation)

tions for operating environment should be followed. Suppliers o f paper tape include Digital Equipment
Corporation and Carter Rice Storrs and Bement.
**Tape o f up to 12% transmittance may be used. Consult DEC for operation o f redder with more transparent
tape.

1-4

CHAPTER 2
INSTALLATION

2.1 INSPECTION
On receipt of the equipment, inspect it for any visible signs of damage in transit, such as dents or abrasions. Inspcct the logic modules for any foreign material that may have lodged in them during shipment. Any damage
observed should be reported immediately to both the carrier and DEC. Check the contents of the carton with
thc shipping document and report any omissions immediately to DEC. Installation is not recommended until all
materials are in hand.

2.2 lNSTALLATION

2.2.1 Mounting
As previously noted, the PCO4/PCO5 is used with different computer systems, and therefore a specific mounting
procedure cannot be included in this manual. The unit is normally mounted in thc central processor cabinet
above the control panel. It can, however, be mounted in an accessory cabinet.

2.2.2 Connections
Refer t o Figure 2-1 for P C 0 connections and Table 2-1 for CPU or BA connections.

Table 2-1
CPU and BA Connections

PDP-8E

Reader Cable M840
Punch Cable M840
M840 Omnibus
-+

PDPSL

Readcr Cable DO 1
Punch Cable CO 1
M040 + C02-C06
M7050 HJ26
M710 HJ28
M7 15 + HJ27

Reader Cable -+C34
Punch Cable (234
M7050 AB30
M710 AB32
M715 AB29

PC04

PDP-81

--f

PDP-1 1
~

Reader Cable M78 1
Punch Cable M78 1
M105+ E13 or E l 4
M781 CD13 or CD14
M782 -+ F13 or F14
-+

PC05

BA12
~

BA15
~

Reader Cable -+ DO6
Punch Cable DO7
M I l 9 + BO6
-+

Reader Cable -+ B28
Punch Cable 13 13
M103+B15
M104+ B10
M 3 1 1 -+ A28
M606 B14
M776 -+ AB22
-+

5
c

PC04 (81)

- P C 0 4 (BE A N 0 8 L )

4
5
-

9 1 0 1 1 1 2

a
0
W

a
W

P0
5

P-

a
0

CP-0133

Figure 2-1 PCO4/PCO5 Module Locations

2.2.3 Module Configurations
Because the reader and punch are available in many configurations, the quantity and type of modules vary. Table
2-2 lists the modules required for each configuration.

2-2

Table 2-2
Module Configurations

Unit

Module

Description

Reader &
Punch

PC04
(PC8E and
PC8L)

G918
M040
M044

Photo Amplifier
Solenoid Driver
Solenoid Driver

PC04
(PC8I)

G918
M040

Photo Amplifier
Solenoid Driver

1
4

0
0

Photo Amplifier
Solenoid Driver
Solenoid Driver
Reader Control
Punch Control
Reader Clock

1
4
3
1

1
4

PC05

G918
M040
M044
M7050
M710
M715

0
1

0
0
3
0
1
0

Reader
Only

Punch
Only

4
3

4
0

0
0

0
1

2.3 POWER REQUIREMENTS
The 3-terminal, I IO-Vac power connectors (PI and P2), located at the rear of the chassis, provide both an input
and an output point for primary power. The connectors, one male and one female, permit the inclusion of the
PCO4/PCO5 in a power chain with other system devices.
Power and signal connections are made in accordance with the procedures given in the applicable IDEC interface,
installation, or maintenance manual.

2.4 CHECKOUT
When the PCO4/PCO5 has been installed, proceed as follows to checkout the unit.
Step

Procedure

Apply power to the computer system and turn on the punch and reader

Load a new carton of tape in the punch tape well, located at the rear of the
chassis, and feed the tape through the punch unit (refer to Paragraph 3.3.1).

Press the punch FEED switch on the front panel. Tape should feed out of the
tape slot and should be unpunched except for feed holes.

Hold the punch FEED switch on until a few feet of tape have been punched.
Tear off the tape and insert it in the reader head, feeding from left to right.

Press the reader FEED switch and observe that the tape feeds evenly without
binding on the edges of the tape guide.

Load and run the applicable MAINDEC diagnostic test (listed in Appendix A),
using the instructions contained with the diagnostic test. If any errors olccur,
refer to Chapter 5 of this manual.

2-3

CHAPTER 3
OPERATION

3.1 INTRODUCTION
This chapter contains information on the PCO4/PCO5 controls, and loading of tape. All programming is done via
the computer. Refer to the respective user’s guide or maintenance manual for this programming information.

3.2 CONTROLS AND FUSES
The controls and fuses for the PCO4/PCO5 are listed in Table 3-1.
Table 3-1
PCO4/PCO5 Controls and Fuses
Nomenclature

Function

PUNCH ON/OFF (SW) (PC04)

Applies power t o punch motor.

PUNCH FEED (SW)

Punches leader tape.

READER ON-LINE/OFF-LINE (SW)

Allows or disallows reading of tape (on-line).

READER FEED (SW)

Manually feeds tape through read station.

3A, SB

Fuses the ac power t o the unit.

Fuses the +5V regulated power input.

Fuses the -1 5V regulated power input.

UNIT ON/OFF (SW)

Switches ac power into the unit.

3.3 OPERATING INSTRUCTIONS
For routine operation of the PCO4/PCO5, refer t o Table 3-1, which describes controls and fuses. Tape loading
procedures are given below.

3.3.1 Loading Blank Tape (refer to Figure 3-1)
To load blank tape for punching, proceed as follows:
Step

Procedure

Pull the unit straight out of the rack on its drawer slides, then flex the tape-feed
bracket and remove and discard the exhausted tape supply carton.

Press the FEED button on the tape punch until the stub end of tape stops moving out of the machine.
(continued o n next page)

3- 1

Step

Procedure

Pull the stub out of the exit slot.

Install a carton of tape in the tape well provided on the rear of the tape punch
chassis.

NOTE
Under certain conditions, such as low humidity,
chad tends to build-up in the plastic punch cover
and subsequently the punch assembly. This condition can be avoided by dipping the plastic punch
cover in an antistatic solution.

Feed the new tape out of the carton, with the printing face down. Route the
tape through the two rollers, over the out-of-tape switch and guide plate, directly
into the punch block (see Figure 3-1).

Guide the tape out over the sprocket and down through the feed-chute tray.

Press and hold the PUNCH FEED switch until several folds of tape are present
in the bin. It is necessary to stack the first few folds by hand to guarantee
proper stacking.

It is good practice to empty the chad box whenever a new box of tape is loaded.

The punch should be oiled monthly by running a box of oiled tape through it
while punching all 1s.

Figure 3-1 Paper Tape Path, Top View

3-2

3.3.2 Loading Prepunched Tape (Figure 3-2)
To load prepunched tape for reading, proceed as follows:

Step

Procedure

Raise the tape depressor and load the tape into the right-hand bin. Thread the
tape under the tape hold-down bracket.

Place the tape on the sprocket teeth and lower the tape depressor fork. Press the
READER FEED switch. Run the tape leader into the left-hand bin and dress the
tape folds.

Figure 3-2 Installing Tape in Paper-Tape Reader

3-3

CHAPTER 4
PRINCIPLES OF OPERATION

This chapter describes the principles of operation for the paper-tape reader (refer t o Paragraph 4.1) and the papertape punch (refer t o Paragraph 4.2). The engineering drawings referenced in this chapter are contained in Volume
2 o f this manual. The principles of operation of the PC05 are described, but they are the same for all versions o f
the reader and punch. A list of all drawings contained in Volume 2 is included in Chapter 6.

4.1 PAPER-TAPE READER
The power and control schematic for the paper-tape reader appears on engineering drawing D-BS-lPC05-0-4, and
D-BS-PC04-0-2.

4.1.1 Tape Feed Operation (Figure 4-1)

Rotation of the reader motor is dependent on the simultaneous actuation of two halves of its two center-tapped
windings. The drive current for the windings is provided by four M040 Solenoid Driver Modules. There arc
actually two drivers per module resulting in eight current drivers or two for each half winding. The stepped activation o f both drivers in each o f two selected modules supplies the current necessary t o produce the required
torque.
Independent gates are provided at the input of each of the eight current drivers. The output of the A or B flipflop activates one driver o f each pair. Each of these drivers feeds into a series-connected current-dividing resistor.
The jumpered ends o f the resistors from each module connect t o one side o f a winding of the motor. Each section
of a driver module provides 600 mA t o a motor winding. With the A and B flip-flop outputs active, only one
driver in each of the two selected modules is activated. Therefore, only 600 mA is applied t o a winding, and the
torque produced by this current, although insufficient t o produce motor rotation, acts as an efficient holding
force.

To fully actuate a motor winding, the second driver in the two selected modules is enabled. This is accomplished
by applying the set output of the POWER flip-flop t o the second driver. With both drivers in each of the two
modules enabled, the output current rises t o 1.2A, which is the current required to rotate the motor.
For example, with flip-flop A (0) and flip-flop B (0) a +3V-level is applied to pins D2 and K2 of the two modules
located at A09 and B07. This condition supplies two of the three required inputs. (Therefore, levels A ( 1 ) and
B (1) are false, disabling the drivers located in slots AI 0 and B08.) The application of a +3V-level (POWER (1))
t o pin E2 of all modules provides the third input required t o the drivers in A09 and €307.

As a result of these three inputs, both sections of drivers in A09 and BO7 conduct, providing drive current to windings 4 and 2 . This drive current rotates the motor 1 .8 degrees. Switching the driver inputs 200 times results in one
complete revolution of the motor (1.8 degrees x 200 = 360 degrees). One motor revolution is equivalent t o 100
character positions. Continuous stepping of the inputs in the proper sequence (see chart in Figure 4-1) at the rate
of 1.667 ms per step produces a tape-feed rate of 300 characters per second.

4- 1

-1BV

CO-0478

Figure 4- 1 Tape Feed Operation
4.1.2 Tape Reading

The photoarray, consisting of nine photosensitive transistors, is arranged below the tape track perpendicular to
the direction of tape movement. A light source, located directly above the phototransistors, provides the light
necessary for sensing holes in the tape. Eight of the phototransistors sense the coded holes; the ninth senses the
feed holes.
The phototransistor, when shuttered from light, controls an output that is below the threshold of the photoamplifier. If the phototransistor is exposed to light, its output current increases in a positive direction and overcomes
the circuit threshold.
The photoamplifier, which consists of nine amplifiers, is used to monitor the outputs of the photoarray. The
photoamplifier provides an output of 5 Vdc when a hole is sensed, and an output of 0.2 Vdc when no hole is
sensed.
The following discussion describes the operation of the channel 1 phototransistor amplifying circuit. All other
channels operate in an identical manner. The referenced amplifying circuit is at the top left of engineering drawing D-BS-PC05-0-4, sheet l .
The photoamplifier ( 0 1 8 ) accepts the output of the photocell for channel 1 at terminal BP2. When the photosensor does not sense light (no hole), the bias level (determined by the setting of the threshold sensitivity potentiometer) is not overcome, which causes a 0 Vdc output at AE2. When the photosensor senses light, a positive
current change occurs at terminal BP2, which is enough to overcome the circuit current threshold, and the output
switches to +5V at AE2.
Approximately 0.1 ms after the data holes are over the photoarray, the feed hole signal rises, strobing the data
into the reader buffer in the M7050.

4- 2

4.1.3 Tape Reader Control

Regardless of the central processor, the control for the PCO4/PCOS is such that the next character to be read is
already directly over the photoarray. The following discussion outlines the cycle involved in reading a character.
a. The central processor issues a fetch character command that generates a tape-advance signal to

the reader. Before this tape-advance signal is actuated, however, the data that is already over
the photoarray is strobed into the buffer register.
h. When the data is stored in the buffer register, the reader control module M70S0 issues the
reader flag.
c.

On detecting the reader flag, the processor issues a command that strobes or ;;ates the data o n t o
eight input-output bus lines and t o the central processor.

d. The tape-advance signal generated in step u brings the next character over the photoarray, and

the process described above is repeated.
4.1.4 Out-of-Tape

The out-of-tape condition arises when attempting t o read with no tape in the reader. A 10 ms one-shot is retriggcred with each fall of the feed hole (tape web). As long as the one-shot is “on”, an out-of-tape does not occur.
If, while trying to read tape, no feed holes are detected, the one-shot times out and an out-of-tape condition
exists. This condition inhibits further attempts t o read. The out-of-tape is cleared by covering the feed hole
sensor when reloading tape in the reader. While stopped between blocks of information, the out-of-tape one-shot
is prevented from timing out by enable being low.
4.1.5 Strobe

Strobe is generated from the signal derived from the feed hole. When the motor has rotated enough to have data
over or approaching the photosensors, a gating flip-flop is turned on. This flip-flop allows detection of a feed hole
and thus generates a strobe. The rise of strobe turns off the above flip-flop and prevents noise on the feed hole
line from generating further strobes. Another strobe is allowed after additional motor rotation.
4.2 PAPER-TAPE PUNCH

The power and control schematic for the paper-tape punch appears on engineering drawing D-BS-IPCOS-0-4, sheets
1 and 2.
4.2.1 Feed Control

A reluctance pick-up (Pulse Generator) signals the M7 10 Punch Control Module when the punch mainshaft has
rotated t o an angular position marking the beginning of the punch cycle. If a character is in the punch buffer at
the time that the pulse generator signal occurs, the punch control immediately applies a voltage across the index
magnet coil and appropriate punch magnet coils.
When the flux in the index magnet coil has built up enough t o overcome the spring return force, the magnet armature ‘‘pulls in” and engages a tooth on the feed ratchet. Continued rotation of the punch mainshaft tries t o draw
the ratchet past the magnet armature. The armature, however, is held stationary and acts as a pawl, resulting in a
rotation of the ratchet. The feed ratchet drives the sprocket wheel through a pair of gears. In this manner, motion
of the paper tape is initiated.

A ball detent on the sprocket wheel shaft is used t o accurately position the tape and then hold the: tape motionless during the ensuing punching operation. Activation of the punch magnets by the solenoid drivers causes

4-3

interposers to be set up. As rotation of the punch mainshaft continues, these interposers push the punch pins
through the paper. As the punch pins are being retracted from the paper, the punch mainshaft is ju!jt completing
one revolution. The reluctance pick-up again signals the logic that the machine is starting a new cycle and is ready
to punch another character.

4.2.2 Tape Punch Control
The punch is selected for operation when it senses its device code or address from the current instruction. Command pulses or data lines are then asserted by the central processor, which subsequently causes IOT pulses to be
generated within the M7 10 Punch Control Module. The IOT pulses clear the punch buffer, load the buffer with
new data, and cause various flags to indicate the state of the punch to the central processor.
A typical operation follows (see Figure 4-2). The punch control senses its device code being transmitted by the
central processor unit (CPU). The CPU checks if the punch is currently active and, if not, sends a command to
clear the punch buffer. Data is then strobed into the buffer from the CPU input-output bus.
A punch command is then sent by the CPU or is generated by the punch FEED switch, and the punch motor is
activated by the SCR. After a 0.4-sec delay to allow the motor to reach full speed, the solenoid drivers are activated, and the punch is allowed to start punching the data in the buffer (PBO-7).
When the punch command is disabled or the punch FEED switch is released, the timer in the M710 module will
time-out after three seconds, unless another punch command is received, and then stops the motor.

pi---’

ADDRESS OR
DEVICE
SELECT

PED-7

BPUNCH
UFFER

CENTRAL
PROCESSOR

----J

CONTROL

7’
PUNCH
FEED

SOLENOID
DRIVER

U T OF T A P E

I -

PUNCH

----MOTOR

t
CO-0471

Figure 4-2 Simplified Block Diagram, Punch Operation
The OUT-OF-TAPE signal provides a warning when approximately 2 in. of tape remains (PC05 only).

4-4

CHAPTER 5
MAINTENANCE

5.1 INTRODUCTION
This chapter contains both preventive and corrective maintenance procedures. An optimum amount of preventive
maintenance, performed on a routine schedule, can eliminate costly equipment breakdowns and allow the detection of impending failures. If a specific item does fail, equipment design is such that replacement of modular
elements can restore the equipment to service in a minimum amount of time. The design objective of the PC04/
PC05 High-speed Paper-Tape Reader/punch is to provide a dependable and relatively maintenance-free assembly.
The tape reader motor is electromagnetically driven; thus, it does not experience the mechanical failures normally
inherent in systems using ratchets, detent, and clutch-brake mechanisms.

5.2 PREVENTIVE MAINTENANCE
Preventive maintenance tasks should be performed at periodic intervals to ensure proper equipment operation and
to minimize unscheduled downtime, These tasks consist of visual inspection, operational checks, cleaning, lubrication, adjustment, and replacement of borderline, or partially defective parts.
Preventive maintenance scheduling is contingent on the environmental and operating conditions ait the installation
site. Under normal environmental and work-load conditions routine preventive maintenance should be ptrformed
after every 600 hours of operation (or every four months, whichever occurs first). This schedule should be modified when extreme temperature, humidity, dust, or work-load conditions exist.
Maintenance activities for the PCO4/PCO5 require the standard test equipment and special materials listed in Table
5-1.

Multimeter

Triplett or Simpson

Model 630-NA or 260

Oscilloscope

Tektronix

Type 547 or 453

Plug-in Unit

Tektronix

Type CA (for 547 scope)

XI 0 Probe

Tektronix

P6008

Module Extender

DEC

Type W980

Tape Registration Gauge
I

5- 1

5.2.1 Preventive Maintenance Procedures
Preventive maintenance procedures for the tape punch can be found in the Roytron Maintenance Manual, which
is supplied with the equipment.

5.2.1.1 Mechanical Checks - Inspect the tape reader periodically as follows:
Step

Procedure

Visually inspect the general condition of the tape reader.

Clean the interior and exterior of the tape reader, using a vacuum cleaner or a
clean cloth that has been moistened with a nonflammable solvent.

Lubricate the chassis slide mechanisms with a light machine oil. Wipe off excess
oil.

Inspect ail wiring and cables for cuts, breaks, fraying, deterioration, kinks, strain,
and mechanical security. Tape, solder, or replace any defective wiring or calble
covering.

Inspect the following components for mechanical security: READER FEED
switch, READER ON/OFF LINE switch, light condensor, phototransistor assembly, depressor arm, holddown bracket, all connectors and circuit modules, tapefeed motor, front cover, and resistor assembly.

5.2.1.2 Electrical Checks - Perform the power supply output checks described in Table 5-2. With the normal
load connected, use a multimeter to measure the output voltages and an oscilloscope to measure thle peak-to-peak
ripple content on all dc outputs of the supply. The +5 Vdc and -15 Vdc supplies are adjustable. The -18 Vdc and
-36 Vdc supplies are not adjustable.
Table 5-2
Power Supply Output Checks
+5V kO.25V

-15V+1V

-1 8V +2V

-36V +4V

0.1v

1 .ov

1.ov

PC04 (81)

AIA

AIB

B6V

B2D

PC04 (8E, 8L)

AIA

AIB

B6V

A5 V

PC05

A1A2

A1B2

B8V2

A8V2

Output Volt age
Ripple (Peak-to-Peak)
Pin
Numbers

5.3 PCO4/PCO5 READER ADJUSTMENTS (FEED-HOLE STROBED MODELS)
5.3.1 Introduction

This section contains the adjustment procedures for the PC04 and PC05 paper-tape readers that strobe data by the
signal derived from the feed holes. The procedures should be followed as closely as possible and should be performed in the order in which they are presented.

Tools and equipment required are listed in Table 5-1. MAINDEC diagnostic programs are listed in Appendix A.
A summarized setup procedure is given in Appendix D. If the unit can read programs, it is advisable to load the
diagnostic in at this time. If not, a ONE-ZERO test tape can be made with a toggle-in routine given in Appendix
B. A read and stall routine can be found in Appendix C.

5-2

This procedure was written for a completely misadjusted machine; adjustments that are already correct need not
be redone. It is good policy, however, to check each adjustment to make sure it is correct.

5.3.2 Preliminary Adjustments
Step

Procedure

Remove power from reader.

Remove tape depressor knob by loosening the two Allen screws that secure it on
the shaft.

Remove the reader front panel by removing the four Phillips screws that hold it
to the front plate.

Remove the protective screen that covers the reader modules and power supply.

Apply power and ensure that +5V = 5V 0.25V and -1 5V = 15V k 1.0V. k d justing potentiometers can be found on the regulator board. (Refer to Table
5-2 and Figure 5-1 .)

+ 8
TAB 4

+5
TAB 1

8VAC
TAB 5

8VAC
TAB 7

+5
POT

Figure 5-1 Regulator Board
5-3

15
POT

GND
TAB 6

-15
TAB 2

- 18
TAB

5.3.3 Test Tape Registration
The following reader adjustment procedure uses the tape output from the punch or a prepunched tape. If this
tape is not in accurate registration (ten characters per inch), the reader may not be able to read other tapes, such
as DEC Program Library tapes. T o check registration, use the following procedure:
Step

Procedure

Obtain a prepunched ONE-ZERO tape or generate a tape with a MAINDEC o r a
toggle-in routine listed in Appendix B.

Use the pins on the tape gauge to check that the registration is not off by more
than one-half feed hole per 6 in. of tape.

The tape gauge provides holes 1 in. apart. Check that every one of these holes is
uncovered. If some holes are covered and the feed holes line up with the tw'o
pins 6 in. apart, registration is off by a multiple of one hole spacing.

It is also important that the feed holes be evenly spaced 0.1 in. from each other.
This can be checked by sighting along the punched tape at a shallow angle.

5.3.4 Feed Wheel and Motor Adjustment
The purpose of this adjustment is to properly position the feed wheel on the motor shaft, thus, placing the data
holes in the paper in their proper relationship with the photosensors.
Step

Procedure

Advance the feed wheel by momentarily pressing the FEED switch. This will ensure that the motor stops on a character and not between characters.

Install a piece of ONE-ZERO test tape (about 6 in. long) over the photo array
and hold it on the feed wheel by means of the tape depressor.

Loosen the four mounting screws that hold the motor to the back plate (three
in front, one in the rear).

Position the motor to the center of its rotational swing and tighten the mounting screws. Repeat Step 1.

Loosen the two Allen screws that hold the feed wheel to the motor shaft.

Move the feed wheel in or out so the tape just comes in contact with the back
plate. The tape must not be jammed against the back plate, nor should there be
a gap between the tape and the back plate. Jamming will cause paper handliing
problems and a gap can cause skew. At the same time, rotate the feed wheel
on the shaft until the holes in the tape have approximately the relation to the
photosensors as shown in Figure 5-2. Tighten the Allen screws.
If the Allen screws have dented the shaft, it may be difficult t o make a small
correction, since the screws tend to slide back into the original dents. To correct this, rotate the wheel on the shaft about one quarter turn and repeat this
step. The important adjustment in this step is the in and out adjustment. Be
sure the tape is not jammed.

Loosen the motor mounting screws again and rotate the motor until the holes
and photosensor appear as in Figure 5-2. This position of the tape allows for
the maximum margin in case of an off registration tape. Repeat Step 1 and
check the alignment per Figure 5-2.

5-4

TAPE MOTION FORWARD

\CELL

LENS

CP-0034

Figure 5-2 Feed Wheel and Motor Adjustment

5.3.5 Tape Depressor
Step

Procedure

Loosen the two Phillips screws holding the tape depressor to the shaft.

Place one thickness of unpunched paper tape (except for feed holes) on the feed
wheel and lower the tape depressor.

Apply light finger pressure on the horizontal position of the tape depressor, centering the slot in the depressor around the feed wheel teeth (see Figure 5-3).

Tighten the screws. The heel and toes of the depressor should now make a fourpoint contact with the paper, holding it evenly against the feed wheel.

TAPE DEPRESSOR

PRESS

PAPER

FOUR POINT
CONTACT
FEED WHEEL

CP-0115

Figure 5-3 Tape Depressor
5.3.6 Tape Hold-Down Bracket

The purpose of this adjustment is to limit the vertical motion of the tape as it passes the read station, yet allow
room for passage of splices and folds.
Step

Procedure

Loosen the two Phillips screws holding the bracket to the back plate.

Insert three thicknesses of unpunched tape (no folds included) under the holddown bracket and up against the back plate.

Press down carefully on the left-hand side of the hold-down bracket and
tighten the screws (see Figure 54).
(continued on next page)

5-5

Step

Procedure

The tape should have even tension as it is being pulled out. If not, the bracket is
bent, and not parallel with the tape path guide. Remove the bracket and adjust it,
checking it with a square or the right angle formed by the tape path guide and the
back plate. Remount and readjust. When the tape depressor is properly adjusted,
point A limits tape skew and point B keeps the paper close t o the photoarray
(Figure 5-4). Maladjustment at either point can cause misreads.

HOLD DOWN BRACKET

HOLD DOWN HERE
(TILT SHOWN I S
EXAGGERATED)

NOTE.
THREE-TAPE THICKNESS
(0.012") AT POI N'TS
A ANDB

TAPE PATH GUIDE

CP-0116

Figure 5-4 Tape Hold-Down Bracket

5.3.7 Lamp, Lens, and Light Pattern
Step

Procedure

Set the adjustable resistor in the lamp circuit (see Figure 5-5) for minimum resistance (maximum brightness). This will reduce the effects of stray outside
light.

Due to the offset filament in the lamp, the lamp should be placed in the reader
so that the end with the lettering is nearest the back plate. This position will
give a more uniform light at the photoarray. Rotate the lamp so the seam is
not projected on the photoarray.

Loosen the lens and rotate it so the light beam is concentrated and centered
over the photoarray. A ONE-ZERO tape with the holes over the photoarray
will help define the light pattern. The pattern should appear as in Figure 5-6,.

5.3.8 Full-Speed Running Rate

Proceed as follows to adjust the full-speed running rate to 300 characters per second, +5 CPS:
Step

Procedure

Connect an oscilloscope to the A(0) flip-flop (refer to Table 5-3 for pin locations).

Run the reader at full speed using either the reader FEED switch or program control.

Check the time between transitions of the A flip-flop. The time should be 3.33
ms (three transitions in 10 ms). The time is adjusted by R6 on the M7 15 (or R27
on the M840 for a PC8E) (see Figure 5-7A).

Check the output (pins R and S) of each M040 Motor Driver Module. Module
locations can be found by referring to Table 5-3. A bad waveform causes faulty
start and stop characteristics and can be caused by a bad M040 or a broken wire
leading to one of the 2 5 q h m , 40W motor resistors. The desired waveform is

shown in Figure 5-7B. Figure 5-7C is an example of a faulty waveform.
5-6

MOTOR
MOUNTING
SCREW
-AMP
RESIST
PHOTO
ARRAY

-.
Figure 5-5 PCO4/PCOS, Rear View

P H O T O T R A N S I S T O R S (9)

FEED HOLE

(CENTERED ON T R A N SISTORS)

IO'
I@ I
I I

~ T A P E
HELD OVER PHOTO T R A N S I S T O R L E N S TO
HELP DEFINE LIGHT PATTERN
CP-0033

Figure 5-6 Light Pattern

5-7

Table 5-3
M040 Motor Driver Input and Output Pin Locations
PC81

PC8E & 8 L

PC05

Out

OlUt

AIP

B3 R&S

A9 D2

A9 R&S

B4 R&S

AIR

B4 R&S

A10 D2

AlCI R&S

A2 S

B5 R&S

AIS

B5 R&S

B7 D2

B7 lR&S

A2T

B6 R&S

AlT

B6 R&S

B8 D2

B8 lR&S

Out

A2 P

B3 R&S

A2R

j-3.33ms

10ms

, ,
*I

ov
(RUNNING RATE)

(GOOD DRIVER)

CP-0112

Figure 5-7 M040 Input and Output Waveforms

5.3.9 Acceleration and Stop Delay
Proceed as follows to determine if the acceleration rate and the stop delay are within specifications. There is no
adjustment. Corrective action should be taken if either condition is not met.
Step

Procedure

Load a program that will read two characters and then stall for approximately
5 ms. Use the MAINDEC program or a short routine listed in Appendix C. The
5-ms stall allows the internal machine stall (stop delay) to activate.

Connect the oscilloscope to the A (0) flip-flop (refer to Table 5-3 for pin locations). The waveform should be either a positive or negative pulse train as
shown in Figure 5-8. The polarity depends on the motor phase the program
happens to start on. Be sure to trigger the oscilloscope on the leading edge of
the narrower pulse, which should be 6 to 7 ms wide. The longer internal pulse is
the stop delay and should be 30 to 70 ms. (Use 10 ms/cm on the oscilloscope to
view this.)

5-8

I---

-1
I

-I

6-7ms

I
!

30-7Oms

I
!
I

C P - 0 1 13

Figure 5-8 Acceleration and Stall Waveforms
5.3.10 Threshold and Skew

Skew can be caused by feed wheel wobble. This wobble causes the tape to walk in and out acros':, the photoarray,
varying the outputs of the photoamplifiers. Skew can also be caused by array placement in the tape path guide
and placement of the individual sensors on the array board. The relative scnsitivity of each sensor in the array
will also cause skew.
Step

Procedure

Using a ONE-ZERO test loop, operate the reader at full speed by either program
control or the FEED switch.

Set the oscilloscope t o 1 ms/cm, 1V/cm, triggering internal positive.

Connect the probe to the feed hole output of the G9 18 test point. See Tatble
5-4 for the pin location.
Table 5-4
G918 Photoamplifier Pin Locations
PC04

PC05

RH 1

A7 E

A l l E2

RH 2

A7 F

AI 1 F2

RH 3

A7 J

AI 1 J 2

RH 4

B7 D

B11 D2

RH 5

A7 L

A l l L2

RH 6

A7 N

A l l N2

RH 7

A7 P

A l l P2

RH 8

A7 R

A l l R2

Feed Hole

A7 T

A l l T2

Sum (TP)

A7 V

A l l V2

Adjust the potentiometer on the G918 for a feed hole pulse width of approximately 1.5 ms. (Measured at the 10%point.)

Observe the pulse stability. If the width varies more than 500 p s (1 / 2 ms) at a
3 cycle per second rate, the feed wheel wobble is too great and the feed wheel
must be replaced. Because the feed wheel makes 3 revolutions per second, the
wobble signal will be a harmonic of 3 Hz. Do not mistake the passage of the tape
loop splice for a variation. Attempts t o straighten the feed wheel are usually ineffective. If the feed wheel must be replaced, repeat the procedure in Paragraph
5.3.4.

(continued on next page)

5-9

Step

Procedure

Observe the waveform at the SUM TP of the G918. It should appear as shown
in Figure 5-9 (A). Measure the time “T” between the last data bit rise and the
feed hole (slow rise signal). The time should be greater than 0.1 ms. If not, adjust by rotating the photoarray in its mounting hole as follows: Loosen the
mounting screw of the photoarray enough t o allow light, finger-pressure movement of the array. Gently rotate the array t o maximize the time “T”. Tighten
the screw.

Turn the potentiometer on the G9 18 counterclockwise until a data bit is picked
up in the all Os section of the waveform. (Do not mistake the feed hole signal
when reading all Os with a picked up bit). Then while counting the turns, turn
the potentiometer in the opposite direction until a data bit or the feed hole is
dropped in the Is section of the waveform and set the potentiometer to the
middle of these two extremes.
These adjustments should be made using the tape with the highest transmissivity
t o be used on the system. For instance, if the reader is to read oiled tape, the
threshold adjustment should be made while using oiled tape.

-I

T MUST BE AT LEAST O . l m s

FEED HOLES

ALL ONES

ALL ZEROES

A . GOOD

FEED HOLE
FEED HOLE
BEFORE
LAST DATA
BIT
BITS.ONE MISSING)

E. BAD (2 CONDITIONS)
CP-0114

Figure 5-9 Summation Waveform, G918 Test Point
8

Recheck for a minimum of 0.1 ms time “T” as described in Step 6 above.

5.3.11 Testing and Error Correction
When the adjustment procedure is completed, test the reader for proper operation by reading a tape for which
there is an error checking routine. The Special Binary count is recommended. If a test loop is used, be careful
that the splice does not generate a false error indication. For testing purposes only, the tape can be run from the
punch t o the reader if the MAINDEC program allows. Review Appendix D for the summary set-up procedure to
be sure all adjustments have been completed.
5.3.1 1.1 Data Bits Picked Up - Data Bits are picked up if:
a. Photosensor not turning on. Return t o threshold adjustment (refer t o Paragraph 5.3.10).

b. Photoarray exposed t o stray light (determine if sunlight is falling o n the reader)

c. Data is picked up during transmission t o processor due t o faulty reader control module, cable,
or processor.

5-10

5.3.1 1.2 Data Bits Dropped -- Data bits are dropped if:
u. Photosensor not turning on. Return t o threshold adjustment, Paragraphs 5.3.7 and 5.3. I O .

h. Skew. Return t o Paragraphs 5.3.4, 5.3.6 and 5.3.10.

c. Data is dropped during transmission to processor due to faulty reader control module, cable.
or processor.

5.3.1 1.3 Skipping Characters - Skipping characters is caused by dropping the feed hole, which c,an be caused by:
u. Skew. Return t o Paragraphs 5.3.4, 5.3.6, 5.3.8 and 5.3.10.

b. Threshold set incorrectly (refer t o Paragraph 5.3.10).

5.3.1 1.4 Double Reading - If the reader reads a character twice, ensure that the adjustments in Paragraphs 5.3.4,
5.3.6, 5.3.8 and 5.3. I O are properly made.
5.3.1 1.5 Dropping Flags - The processor may lose the reader flag because of an out-of-tape indication. This may
happen because of missing reader strobes (refer t o Paragraph 5.3.1 I ) .
5.3.1 1.6 Out-of-Tape Circuit - The out-of-tape circuit clears itself when a web is found. If a web does not occur
within 10 ms of an enable-to-read, the out-of-tape occurs, the flag i s reset, and further commands to read are ignored. A bad M040 motor driver can cause a slow enough start that the I O ms one-shot will timeout before it is
retriggered by the next feed hole. Recheck M040 waveforms, Paragraph 5.3.8, Step 4.
5.3.1 I .7 Acceptance Testing - With all adjustments complete, the PC05 is capable of running any program. A
reasonable acceptance program consists of running one box of tape, which is equivalent to 6 in. of vertical stacked
height. For reference, each vertical inch represents 6 to 8 minutes of full-speed punching time.
5.4 PUNCH ADJUSTMENT PROCEDURES
5.4.1 General
This section contains adjustment procedures for the punch mechanism. Additional information can be obtained
from the Roytron Afuintenance Manual, which is supplied with each unit.

5.4.2 Tape Output Quality
At times, troubles relating t o data being dropped or picked up can be caused by incorrect alignment of feed and
data holes. Figure 5-10 shows the correct dimensions for paper tape in accordance with the USA Standard for
1%. perforated paper tape.
Punched-hole diameters and transverse centerline dimensions are almost never out of specification because the
punches and die blocks are made from hard tooling. There are no adjustments involved in setting up these dimensions.
Two dimensions that do involve mechanical adjustments are the 0.392-in. dimension from the feed hole centerline t o the rcference edgc of the tape, and the 0.100-in. dimension between adjacent'feed holes. Eloth of these
dimensions depend on properly positioning the sprocket wheel on its shaft. If the 0.100-in. dimension is consistcntly long or zonsistently short, adjustment of the angular position of the sprocket wheel on its carrier shaft
will eliminate the problem.

5-1 1

-1h-f

0003

CODE H O L E L O C A T I O N
WITH RESPECT TO
0100 I N C H G R I D

0072 DIA ? 0002

E N C E EDGE

CUMULATIVE
SPACING ERROR
UP TO + O O l O I N 1.0 I N C H
UP TO 0.025 I N 5.0 INCHES

0.500
C O 0473

Figure 5-10 Specifications for 1-In. Paper Tape

5.4.2.1 Sprocket Wheel Adjustment - Burrs on the sides of the feed holes indicate that the sprocklet wheel is not
positioned t o pull tape squarely through the punch. Adjust the sprocket wheel as follows:
Step

Procedure

Loosen the set screws on the sprocket wheel and slide the wheel along its h a f t
until the sprocket teeth are directly in line with the feed hole punch.

Line up the sprocket by removing the tape skew guide at the rear o f the die block
and then placing a punched length of good tape in the die block. Ensure that
the reference edge of the tape is squarely against the guiding edge of the die block.
The feed hole in the tape can be used t o accurately gauge the position of the
sprocket.

Longitudinal registration may requiI e adjustment after repositioning the sprocket.
Once proper registration has been achieved, the set screws in the sprocket wheel
must be tightened firmly so that the sprocket wheel does not creep sideway:;
back into its original position.

5.4.2.2.Burred Feed Holes - Burrs on the front or back edges of the feed holes can be caused by excessive drag
on the tape or by a timing problem in the sprocket wheel motion.
5.4.2.3 Elongated Feed Holes - If the paper drive sprocket moves while the punches are piercing the paper, the
feed holes in the tape will be elongated or burred. There are several ways in which this can happen.
a. An eccentric shaft around which the entire punch yoke pivots determines the length of time

allowed between the initiation of paper feed motion and the instant the punch pins enter the

(continued on next page)
5-12

paper. Improper angular positioning of this shaft may leave too little time for paper motijon.
The sprocket will still be moving the paper as the punches enter the paper. The punch pins will
lock the paper in place, and the subsequent settling motion of the sprocket wheel will cause the
feed holes engaged with the sprocket teeth t o be elongated.
The time allowed between the feeding and punching operations is 7 ms k0.3 ms o r 126 degrees
25 degrees of the punch cycle. The paper feed motion begins at 105 degrees in the punch cycle;
the punch pins begin t o pierce the paper at 23 1 degrees. The difference is the time allowed for
paper motion.
b. A large diameter knob installed on the sprocket shaft of the punch will greatly increase the rotary inertia o f the paper-positioning mechanism and will lengthen the time required t o position
the paper tape. As a result, even in a properly timed punch, the paper will still be moving when
the punches enter the paper. The large knob must be replaced by a smaller plastic knob having
an outside diameter no greater than 3/4 in. This knob is stocked as DEC part no. 12-09904.
c. A final adjustment affecting the motion of the paper concerns the forward indexing magnet.

Specification of the adjustment of this magnet is gjven in Paragraph 5.4.6. If the magnet ;Irmature engages too far out on the ratchet tooth, the ratchet and sprocket will receive a larger than
normal acceleration and a longer period of time will be required for the tape t o be positioned.
Punch pins will enter the paper before the paper has been properly positioned.
At 205 degrees in the punch cycle, the magnet armature must just miss contacting the ratchet
tooth; otherwise, the paper drive sprocket will be disturbed and will not be able t o reposition
the tape before the punch pins enter the paper.

A simple registration adjustment will eliminate burrs on feed holes only if the feed hole spacing
is drastically incorrect (more than 0.100 in. error per inch; i.e., 9 o r 1 1 holes per in. instead of
10). In all other cases, the cause for burring must be corrected before attempting t o register
the punch.

5.4.3 Tape Depressor
The tape depressor mechanism (see Figure 5-1 1) is a new device that is added, by DEC, t o the punch in place of
the lucite cover and hinge. This mechanism is in the form of an assembly, which is held on the punch platen by
two spring clamps and two screws. The assembly is properly positioned when the radius of the tape depressor
arm conforms t o the radius of the drive sprocket, and when the sprocket teeth pass through the slot provided in
the tape depressor arm. The whole assembly is shifted t o make these adjustments.
The latch is still used with this tape depressor but, now that the tape depressor is spring-loaded against the drive
sprocket, the latch serves only t o hold the depressor in place when tape is first started through the unit. In normal operation, there should be about 0.010-in. free play between the latch and the depressor tab.

5.4.4 Electrical Parameters (see Figure 5-12)
Basic timing for the punch system comes from a reluctance-type pulse generator, which supplies a positive-going
and a negative-going pulse for every revolution of the punch mainshaft. The positive-going pulse signals the beginning of the punch cycle. If the amplitude of this signal is not great enough t o trigger the electronics, the generator
air gap must be reduced; this is done by loosening the generator coil assembly and moving it closer t o the generator disc. The coil must not rub against the disc. The correct gap is .004 ? .002. Refer t o Paragraph 5.4.6. l t o adjust the generator air gap.
It is possible for the coil core t o become demagnetized. A weak signal will result. The core may be remagnetized
by momentarily applying 36V t o the coil. The voltage polarity is important. Proceed as follows:

5-13

With power off, remove punch cable card from its slot. Make a temporary connection from Pin
F of cable card to -36V and connect Pin V to Ground. Turn the power on, then off. The coil is
polarized. The punch cable card may be plugged into any unused slot in order to apply the: polarizing voltages.

b. Remove temporary jumper wires and plug cable punch card back into its proper slot.

c. If the SYNC PUN signal remains below an acceptable level, the coil assembly may be defective.
If placing a screwdriver blade against the exposed core end causes a significant rise in output
level, it is an indication that the assembly should be replaced.
TAPE DEPRESSOR

1
T A P E CHUTE

NYLON W

TORSION SPRING

E - RING
CO-0476

Figure 5-1 1 Improved Tape Depressor
MAINSHAFT
POSITION

360°

1800

e@I

P U L S E GENERATOR O U T P U T

-9..5msT;5rns7

Z05ms

-22 TO-38V
PUNCH M A G N E T C O I L V O L T A G E
CO-0474

Figure 5-12 Electrical Parameters

5-14

Magnets in the punch must be energized by some voltage between 22 and 38V. Voltages are applied to the magnets at the beyinning of the punch cycle and must remain for exactly half of the punch cycle. This is usually 9.5
ms, but it can vary slightly depending on line voltage, line frequency, and on the hole pattern being punched.
(Punching all holes requires much more torque than punching only feed holes. The punch motor slows down
slightly under increased load.) Turning the magnets off early may cause dropping of bits. Leaving magnets on too
long will wear out the forward index magnet armature at its tip.
The gear ratio between the electric motor and the punch is critical. The punch mainshaft pulley has 18 grooves;
60-cycle motor pulleys have 16 grooves; 50-cycle motor pulleys have 20 grooves. A 50-cycle gear ratio unit plugged into a 60 cycle outlet will cause the punch to run too fast. Registration will be exceedingly poor.

5.4.5 Basic Timing
There are three basic adjustments that affect the times at which events occur within the punch.
When the punch starts its cycle, the first event is the engagement of the forward index magnet annature with the
ratchet wheel. The magnet armature actually pulls in against the ratchet wheel, and the ratchet moving past the
armature causes a tooth to be engaged and paper motion begins. This engagement must occur as early as possible
in the punch cycle. As soon as the punch pins have been withdrawn from the paper during the preceding punch
cycle, the new paper motion can occur. This is placed at 105 degrees in the punch cycle.
The next event is the piercing of the paper by the punch pins. This operation must be delayed for a period of
time (7 ms) while the detent positions the paper. Piercing the paper begins at 23 1 degrees in the punch cycle.
Neither the 105 nor the 231 degree settings are critical in themselves. However, the difference between these two
settings is critical (this is the time allowed for paper to move from one character position to the next). In general,
if the difference in these two settings is less than 1 19 degrees, the punch probably will burr feed holes and will
wander in and out of registration, depending on the hole pattern being punched, the fold position in relation to
the punch die block at the time the hole is punched, etc.
Proper ratchet and pawl (armature) engagement is checked with the mainshaft rotated to the 205-degree position.
At this point, with the pawl in its energized position, the ratchet and pawl are at their nearest point following the
paper feed. The pawl should just contact the ratchet at this time, but no motion of the ratchet should result. If
this adjustment is not correct, the ratchet must be repositioned on its shaft. This is easily done b y loosening the
two set screws in the ratchet. After making this adjustment be sure that the pawl is about 0.005 in. from contacting the root of the ratchet tooth when the pawl and ratchet are engaged.
Once the ratchet and pawl have been adjusted, the alloted time between feeding and punching of paper can be set.
'There are two methods to determine whether the proper amount of time is being allotted, but only one adjustment,
the Pawl Carrier Eccentric Shaft, actually affects this time.

5.4.5.1 Method ( 1 ) - Refer to Figure 5-13. Remove the lucite chad guide and install gauges (DEC No. 29-15 194)
in the number 1 and 8 holes in the die assembly.
Select the number 1 and 8 punches and rotate the mainshaft (7) until the high point of shaft (7) is completely to
the rear (307 degrees on the timing dial). The previously inserted pins must raise 0.080 +0.010 above the surface
of the plate (2).
When adjustment is required, loosen lock nuts ( I 1) on both sides of the unit and turn Pawl Carrier Eccentric Shaft
(10) to increase or decrease the amount of movement imparted to the punch pins.

5-15

5.4.5.2 Method (2) - Insert a feeler gauge or other hard flat device between the die blocks ( I and Z!) so that the
punch travel is obstructed. Set up a punch, and rotate the mainshaft (7) until the punch comes up ragainst the
feeler gauge. This should occur at 23 1 degrees in the punch cycle, or 126 degrees after the initiation of the paperfeed motion (which should occur at 105 degrees).

If adjustment is required, loosen lock nuts ( 1 1) on both sides of the unit and turn Pawl Carrier Eccentric Shaft
(IO) until the desired 126-degree difference is reached.

Figure 5-13 Punch Assembly*

NOTE
Changing the position of the eccentric shaft (10) may
necessitate the adjustment of all eight punch magnet
air gaps. I t is not recommended that this magnet adjustment be attempted in the field.

5.4.6 Magnet Adjustments
There are three magnet air gap adjustments; all are critical.

5.4.6.1 Pulse Generator Air Gap - The Pulse Generator Air Gap is the easiest to adjust. Firmly pinch a single
layer of paper tape between the coil pole piece and the pulse generator disc and tighten the pole piece in place.
5.4.6.2 Forward Index Magnet Armature Adjustment - The Forward Index Magnet Armature Adjustments (Figure 5-14) are the most critical adjustments in the machine and most frequently the adjustments in need of attention.

5-16

I
2

0.0052 0.001

10'

ir
C0-0472

Figure 5-14 Forward Index Magnet Armature
a. The Armature Assembly (71, when operated, must have 0.005 +O.OOl-in. gap between Magnet

Shell (9) and Armature (7). Adjustment may be made by loosening Binding Screws (6 and 11)
and repositioning either the Armature Assembly (7) or Plate (10).

b. Prior to performing the adjustments to the Indexing Ratchets, the Detent Wheel must be secure
on the Sprocket Shaft, and the Detent Balls must be located in the Teeth of the Detent Wheel.

c. Index Magnet (8), when called, must bring Interposer (4) t o within 0.005 in. of the bottom of
Forward or Reverse Feed Ratchets (2).
d. The Index Magnet Armature may be held in its energized position by looping a rubber band
around the armature and coil.
e. To adjust the Index Magnets, loosen Binding Screws (51, and move Magnet and Interposer Assembly to obtain the above clearance.

f Rotate the Timing Dial to 205 degrees and operate Forward Interposer (4). Interposer (4)
must contact Ratchet ( 2 ) with no play between the top of Interposer (4) and Ratchet Toloth
(3). If adjustment is necessary, loosen Set Screws ( l ) , and reposition Ratchet (2). Check this
adjustment on all Teeth of the Ratchet.
g. On late style units, the Forward Index Magnet Rear Mounting Screw Hole has been enlarged to
permit the Forward Index Magnet adjustment to be made in the following manner: Loosen
Screws (5) and pull Magnet (8) to the rear of the Unit so the Rear Screw rests on the edge of
the enlarged hole. Rotate Magnet (8) forward until Interposer (4) meets the 0.005-in. clearance
as previously described. Tighten Screws (5).

5.4.6.3 Punch Magnet Adjustment - The Punch Magnet Adjustments (see Figure 5-1 5) are very difficult to measure without taking a side frame off the machine. It is not recommended that this be attempted in the field. The
punch magnet adjustments are the least critical of the magnet adjustments, and a machine seldom requires attention in this area.

5-17

3 (omit for new style)

t 0.004
Oooo4 -0.000
6

0.002 t o 0.008

Figure 5-15 Punch Magnet
a. If adjustment is necessary, loosen Binding Screws ( 1 ) and move Plate (2) so there is 0.004 in.
(+0.004, -0.000-in.) clearance between Armature (6) and Shell ( 5 ) as indicated, with Bowed
Spring (3) in the position shown.

b. Set the Timing Dial at 127 degrees. There must be 0.002- to .008-in. air gap between Armature
(6) and Point (7) of Shell (5). When required, loosen Screw (4) and move the Magnet forward
or backward to obtain the aforementioned clearance.

5-1 8

CHAPTER 6
REFERENCE DRAWING LIST

This chapter contains a list of reference drawings required for maintenance of the PC04 and PCOS. Table 6-1 lists
the PC04 drawings by number and title and Table 6-2 lists the PC05 drawings. Table 6-3 lists the module circuit
schematics. Refer to the appropriate Module Utilization List for applicable modules. The actual drawings are
contained in Volume 2 of this manual.
Table 6-1
PC04 Engineering Drawings
Number

Title

Revision

D-DI-PC04-0-1
D-UAPCO4-0-0
A-PL-PCO4-0-0
D-BS-PC04-0-2
C-MU-PC04-0-3
A-PL-PCO4-0-3
E-AD-7006268-8-0
A-PL-7006268-0-0
A-SP-PCO4-0-4

Drawing Index
Unit Assembly
Unit Assembly, Parts List
Power and Control Schematic Diagram
Module Utilization List
Parts List, Modules
Bus Bar
Bus Bar, Parts List
PC04 Engineering Specification
Table 6-2

PC05 Engineering Drawings
Number

Revision

Title

D-DI-PC05-0- 1
D-UA-PC05-0-0
A-PL-PC0 5 -0-0
D-BS-PC05-0-4
C-MU-PC05-0-3
A-PL-PC0 5-0-3
C-AD-7006253-0-0
A-PL-7006253-0-0

S
M
M
F
B
B
C
C

Drawing Index
Unit Assembly
Unit Assembly, Parts List
Power and Control Schematic
Module Utilization List
Parts List, Modules
Bus Bar
Bus Bar, Parts List

6- 1

Table 6-3
PCO4/PCQ5 Module Circuit Schematics

Solenoid Driver
Punch Control
Reader Clock
Reader/punch Control
Reader Control

B-CS-M044-0-1
D-CS-M7 10-0-1
C-CS-M7 15-0-1
E-CS-M840-0- 1
D-CS-M7050-0-1

6-2

APPENDIX A
DIAGNOSTIC PROGRAMS

The following are suggested MAINDEC test programs.
Suggested MAINDEC Reader Test Programs
PDP-8E

MAINDEC-8E-D2CA

PDP-8,81,8L, PDP-12

MAINDEC-08-D2GC

PDP-1 1

MAINDEC-1 1-D2BA

PDP- 1 5

MAINDEC-1 5-D2CA

A- 1

APPENDIX B
SUGGESTED PROGRAMS FOR ALTERNATE
ONES AND ZEROS TEST TAPES

The following is a list of ONES and ZEROS Tape Test programs.

Address

Mnemonic

Octal

PDP-8, 81, 8L,
PDP-12, 8E

0200
020 1
0202
0203
0204

CMA
PLS
PSF
JMP- 1
JMP200

7040
6026
602 1
5202
5200

PDP-I 1

200
206
212
214
222
226
230

01 2737
105737
100375
012737
105737
100375
000 137

177777
177554

177556

000000
177554

177556

01
11
21
31
41
51

CLA
PSA
PSF
JMP-1
CMA
JMP-4

PDP-9, 15

000200
750000
700204
70020 1
600002
74000 1
60000 1

--.

B- 1

MOV
TSTB
BPL
MOV
TSTB
BPL
JMP

#177777, @#I77556
@#177554
.-4
#0, @#I77556
@ 177554
.-4

START

APPENDIX C
STALL PROGRAMS

Stall programs for the PCO4/PCO5 are listed below.

Suggested 5-ms Stall Program
Multiple Character
(Switch reg = N, Number of characters to read)

Add
PDP-8E, 81, 8L, 12

200
20 1
202
203
204
205
206
207
210
21 1
212
213
214
215
216
217

Start

Mnemonic

Octal

CLL CLA
LAS
CIA
DCA 220
TAD 217
DCA 22 1
CLL CLA
RRB RFC

7300
7604
704 1
3220
1217
322 1
7300
6016
601 1
5210
2220
5206
2221
5214
5200
0000

RSF
JMP -.1
ISZ 220
JMP A
ISZ -. 1
JMP -.1
JMP START
0

c-1

READ N Char.
STALL (5-15 ms)

(10 ms)

Address

Mnemonic

Octal

0200
020 1
0202
0203
0204
0205
0206
0207
0210

LAS
AND MSKl
CMA
DAC COUNT
RSA
RSF
JMP.- 1
ISZ COUNT
JMP READ

750004
500221
74000 1
0402 17
700 104
700101
600205
4402 17
600204

021 1
0212
0213
0214
0215
0216

LAS
AND MSK2
DAC PAUSE
ISZ PAUSE
JMP.- 1
JMP BEGIN

750004
500222
040220
440220
6002 14
600200

PDP-9 and
PDP- 1 5

Read
16
Lines

Stall
Between
Groups

Count 0217 0
Pause 0220 0
MSKl 0221 000777
MSK2 0222 777000
AC SWITCHES = 600017 (Bits 0 t o 8 determine stall time. Bits 9 t o 17 = number
of characters -1 to be read between stalls.)

PDP-1 1 Read “N” Characters
And Stall 5 ms Program
(Set SR = N, Number of bits to read)
Address
PDP-1 1

200
204
210
214
216
220
222
226
230
232

Octal
013703
105237
105737
100375
005303
001371
012704
005304
100376
000137

177570
177550
177550

003000

000200

Mnemonic
Read: MOV SR, %3
INCB PRS
TSTB PRS
BPL .-4
DEC %3
BNR .-12
Stall: MOV 3000, %4
DEC 764
BPL .-2
JMP READ

c-2

---.

APPENDIX D
SUMMARY SET-UP PROCEDURE

The following is a summary set-up procedure:

Procedure

Step
1

Feed wheel and motor adjusted correctly (5.3.4).

Tape depressor aligned correctly (5.3.5).

Tape Hold Down Bracket set for three tape thicknesses (5.3.6).

Lamps, lens, and light pattern adjusted properly (5.3.7).

Full speed running rate set for 3.33 ms/character (5.3.8).

Acceleration and stop delay within tolerances (5.3.9).

Threshold set midway between pickup and drop out errors ( 5 . 3 .IO).

Skew greater than 0.1 ms (5.3.10).

D- 1

Digital Equipment Corporation
Maynard, Massachusetts

printed in U.S.A.