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Document:	DECconcentrator 500 Problem Solving
Order Number:	EK-DEFCN-PS
Revision:	004
Pages:	77
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DECconcentrator 500
TM

Problem Solving

Order Number: EK–DEFCN–PS–004

NOTICE – Class 1 Laser Device:
The lasers in this equipment are Class 1 devices, compliant with CDRH Rules 21, CFR
Subchapter J, Part 1040.10, at date of manufacture. Class 1 laser devices are not
considered to be hazardous.

NOTICE – Class A Computing Device:
This equipment generates, uses, and may emit radio frequency energy. The equipment has
been type tested and found to comply with the limits for a Class A computing device
pursuant to Subpart J of Part 15 of FCC Rules, which are designed to provide reasonable
protection against such radio frequency interference when operated in a commercial
environment. Operation of this equipment in a residential area may cause interference; in
which case, measures taken to correct the interference are at the user’s expense.

CAUTION
The people who install the cabling system described in this manual should know local
building codes, fire codes, and any other applicable codes or regulations. The manufacturers
or their distributors and agents will not be responsible for damage due to improperly
installed cabling, neglect, misuse, or improper connection of devices to the cabling system.

DECconcentrator 500

Problem Solving

January 1992
This manual describes how to troubleshoot and service the
DECconcentrator 500 unit. Information includes an overview,
troubleshooting and testing, and removal and replacement
procedures.
For additional information about the option cards, refer to the
specific option card installation documentation.
Supersession/Update Information:

Order Number: EK–DEFCN–PS–004

This is a revised manual.

EK–DEFCN–PS–004
January 1992

The information in this document is subject to change without notice and should not be construed as a
commitment by Digital Equipment Corporation. Digital Equipment Corporation assumes no responsibility for
any errors that may appear in this document.

The following are trademarks of Digital Equipment Corporation:

DEC
DECbridge
DECconcentrator
DECconnect
DECelms
DECmcc

DECndu
DECnet
DECrepeater
DECUS
DELNI
DEMPR

DESTA
ThinWire
UNIBUS
VAX
VAXcluster
VAXstation
VMS

Hewlett-Packard and HP are registered trademarks of Hewlett-Packard Company.

ST is a trademark of American Telephone and Telegraph Company.

This manual was produced by Telecommunications and Networks Publications.

Contents
Preface

Controls and Indicators
1.1
1.2
1.3

1–1
1–2
1–3

Troubleshooting and Testing
2.1
2.2
2.3
2.4
2.4.1
2.4.2
2.5
2.6
2.7

Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Network Management Switch . . . . . . . . . . . . . . . . . . . . . . . . . .
Out-of-Band Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tools and References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Problem-Solving Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Network Management Initiated Self-Test . . . . . . . . . . . . . . .
Power-up Initiated Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . .
Problem Solving Using the LED Indicators . . . . . . . . . . . . . . . .
Loopback Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measuring the Optical Power . . . . . . . . . . . . . . . . . . . . . . . . . . .

2–1
2–1
2–2
2–2
2–3
2–3
2–7
2–10
2–10

Removal and Replacement Procedures
3.1
3.1.1
3.1.2

Preparing the Concentrator for Servicing . . . . . . . . . . . . . . . . . .
Removing and Replacing the Plastic Enclosure . . . . . . . . . . .
Removing and Replacing a Rackmount Unit . . . . . . . . . . . . .

3–1
3–2
3–4

iii

3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.2.6
3.2.7
3.2.8
3.3

Removing and Replacing Concentrator FRUs . . . . . . . . . . . . . .
Removing and Replacing Option Cards . . . . . . . . . . . . . . . . .
Opening the Chassis Cover . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing and Replacing the OBM Card . . . . . . . . . . . . . . . .
Removing and Replacing the Controller/Backplane Board . .
Removing and Replacing the Fan . . . . . . . . . . . . . . . . . . . . .
Removing and Replacing the Power Supply . . . . . . . . . . . . .
Removing and Replacing the Power Connector and Filter . .
Removing and Replacing the Circuit Breaker . . . . . . . . . . . .
Reassembling and Reinstallating the Concentrator . . . . . . . . . .

Parts List

Specifications
B.1
B.1.1
B.1.2
B.2
B.3
B.4
B.5
B.6

Physical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fiber Cable Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Specifications for ThinWire and Shielded Twisted-Pair
Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ThinWire Cabling Specifications . . . . . . . . . . . . . . . . . . . . . . . .
Shielded Twisted-Pair Cabling Specifications . . . . . . . . . . . . . .

3–6
3–8
3–10
3–12
3–14
3–16
3–18
3–20
3–22
3–24

B–1
B–2
B–3
B–4
B–5
B–7
B–7
B–7

Related Documents

Figures
1–1:
2–1:
2–2:

Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fault and Port Status LED Problem-Solving Flow Chart . . . . . .
Measuring the Transmit Power (Multimode) . . . . . . . . . . . . . . .

1–1
2–4
2–12

2–3:
3–1:
3–2:
3–3:
3–4:
3–5:
3–6:
3–7:
3–8:
3–9:
3–10:
3–11:
A–1:

Measuring the Receive Power (Multimode) . . . . . . . . . . . . . . . .
Plastic Enclosure Removal and Replacement . . . . . . . . . . . . . . .
Rackmount Unit Removal and Replacement . . . . . . . . . . . . . . .
Rackmount Bracket Removal and Replacement . . . . . . . . . . . . .
Option Card Removal and Replacement . . . . . . . . . . . . . . . . . . .
Chassis Cover Removal and Replacement . . . . . . . . . . . . . . . . .
OBM Card Removal and Replacement . . . . . . . . . . . . . . . . . . . .
Controller/Backplane Board Removal and Replacement . . . . . .
Fan Removal and Replacement . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Removal and Replacement . . . . . . . . . . . . . . . . .
Power Connector and Filter Removal and Replacement . . . . . .
Circuit Breaker Removal and Replacement . . . . . . . . . . . . . . . .
DECconcentrator 500 FRUs . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2–14
3–3
3–5
3–6
3–9
3–11
3–13
3–15
3–17
3–19
3–21
3–23
A–2

DECconcentrator 500 Controls and Connectors . . . . . . . . . . . . .
DECconcentrator 500 Indicators . . . . . . . . . . . . . . . . . . . . . . . .
Network Management Configuration Switch Settings . . . . . . . .
Main Unit Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Network Management Card Problem Solving . . . . . . . . . . . . . .
Port Card Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optical Bypass Relay Problem Solving . . . . . . . . . . . . . . . . . . .
Problem Solving During Loopback Testing . . . . . . . . . . . . . . . .
FDDI Transmit and Receive Power Calculation . . . . . . . . . . . . .
DECconcentrator 500 Parts List . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . .
Multimode Fiber Cable Specifications . . . . . . . . . . . . . . . . . . . .
Alternate Multimode Fiber Cable Specifications . . . . . . . . . . . .
Single-Mode Fiber Cable Specifications . . . . . . . . . . . . . . . . . .

1–2
1–2
1–3
2–7
2–8
2–8
2–9
2–10
2–15
A–3
B–1
B–2
B–3
B–4
B–5
B–6
B–6

Tables
1–1:
1–2:
1–3:
2–1:
2–2:
2–3:
2–4:
2–5:
2–6:
A–1:
B–1:
B–2:
B–3:
B–4:
B–5:
B–6:
B–7:

Safety

Any warning or caution that appears in this manual is defined as follows:
Warning

Contains information to prevent personal injury.

Caution

Contains information to prevent damage to equipment.

Vorsicht

Enthält Informationen, die beachtet werden müssen, um
den Benutzer vor Schaden zu bewahren.

Achtung

Enthält Informationen, die beachtet werden müssen, um
die Geräte vor Schaden zu bewahren.

Danger

Signale les informations destinées à prévenir les accidents
corporels.

Attention

Signale les informations destinées à prévenir la détérioration
du matériel.

Aviso

Contiene información para evitar daños personales.

Precaucion

Contiene información para evitar daños al equipo.

vii

The warnings and cautions you must observe for the hardware described in this manual
are listed below in English, German, French, and Spanish. The pages on which these safety
messages appear are also listed.

WARNING

Disconnect the ac power cord before removing any field-replaceable units. Do not apply power to the wiring concentrator
unless all covers are installed. Only qualified service engineers should perform any of these removal and replacement
procedures. (3–1)

VORSICHT

Ziehen Sie immer zuerst das Netzkabel aus der Wandsteckdose, wenn Sie FRUs entfernen oder austauschen müssen.
Sie dürfen an den Kabelkonzentrator erst dann Spannung anlegen, wenn alle Abdeckungen ordnungsgemäß angebracht
sind. Diese Arbeiten dürfen nur von qualifiziertem Wartungs-personal durchgeführt werden.

DANGER

Avant de procéder à la dépose d’unités remplaçables, débranchez le cordon d’alimentation. Ne reliez le concentrateur de
câblesau secteur qu’après l’installation complète de tous les
capots. Seuls des techniciens de maintenance qualifiés sont
habilitésà effectuer les opérations de dépose et de pose.

AVISO

Se desconecta el cable de corriente alterna antes de quitar
cualquier parte que se vaya a sustituir. No transmitir corriente al concentrador a menos que se hayan instalado todas
las cubiertas.

WARNING

Some fiber optic equipment can emit laser light that can injure
your eyes. Never look into an optical fiber or connector port.
Always assume the cable is connected to a light source. (3–1)

VORSICHT

Schauen Sie niemals direkt in ein Glasfaserkabel oder einen
Glasfaseranschluß. Die Laserstrahlen in faser-optischen
Geräten können Augenverletzungen verursachen.

DANGER

Certains équipements utilisant les fibres optiques peuvent
émettredes rayonne-ment laser dangereux pour les yeux. Ne
vous avisez jamais de regarder par
l’extrémité d’une fibre
optique ou dans l’ouverture d’un connecteur. Considérez
toujours que le câble est relié à une source lumineuse.

viii

AVISO

WARNING

Algunos equipos de fibra óptica pueden emitir luz láser que
dañalos ojos. No sedebe mirar en una puerta de conector o
fibraóptica. Siempre se debe suponer que el cable está conectado a la luz.

Always remove the power cord from the wiring concentrator
and ac source when performing any removal and replacement
procedures. Also remove any port cable connectors when
servicing the wiring concentrator. (3–2, 3–4)

VORSICHT

Ziehen Sie immer zuerst das Netzkabel aus der Steckdose
und anschließend aus dem Kabelkonzentrator, wenn Sie
Teile entfernen oder austauschen müssen. Bei Wartungsarbeiten am Kabelkonzentrator müssen Sie außerdem alle anderen Kabel abziehen.

DANGER

Assurez-vous toujours que le cordon d’alimentation est
débranchédu concentrateur et du secteur lors desprocédures
de dépose et pose de composants. Débranchez tous les connecteurs des ports du concentrateur lors des opérations d’entretien.

AVISO

Se debe sacar el cable de alimentación del concentrador y
eliminar cualquier corriente alterna antes de realizar cualquier tarea de sustitución. También se debe quitar cualquier
conectar del cable de puerta mientras se trabaja con el concentrador.

WARNING

Do not attempt to remove any of the field-replaceable units
(including the option boards) while the ac power cord is connected or while there is power to the wiring concentrator
(ON). Safety regulations require all covers to be installed before applying power to the wiring concentrator. Removal and
installation of the field-replaceable units should only be performed by qualified service personnel. (3–7)

VORSICHT

Versuchen Sie nicht, FRUs zu entfernen (einschließlich der
Erweiterungskarten), solange das Gerät an das Strom-netz
angeschlossen ist oder am Kabelkonzentrator Spannung anliegt. Vergewissern Sie sich, daß alle Abdeckungen angebracht sind, bevor Sie den Kabelkonzentrator mit dem Netz
verbinden. FRUs dürfen nur von qualifiziertem Wartungspersonal entfernt oder ausgetauscht werden.

DANGER

N’essayez pas de déposer des unités remplaçables (y compris
les cartes en option) sans avoir au préalable débranché le cordon d’alimentation ou mis le concentrateur hors tension.
Les instructions de sécurité imposent que tous les capots soient installés avant la mise sous tension. Seuls des techniciens de maintenance qualifiés sont habilités à effectuer les
opérationsde dépose et de pose des unités remplaçables.

AVISO

No se debe tratar de quitar ninguna unidad reemplazable
(incluyendo las placas de opciones) mientras esté conectado
el cable de corriente alterna o mientras haya corriente en el
concentrador. Las regulaciones de seguridad exigen que
esténinstaladas todas las cubiertas antes de aplicar corriente
al concentrador. La sustitución de aquellas partes que se puedan reemplazar sólo debería realizarla personal cualificado.

WARNING

Do not atttempt to remove the chassis cover while the ac power cord is connected or while there is power to the wiring concentrator. Chassis cover and field-replaceable unit removal
should only be performed by qualified service personnel.
(3–10)

VORSICHT

Das Gehäuse darf erstgeöffnet werden, wenn das Netzkabel
aus der Steckdose gezogen ist und am Kabelkonzentrator
keine Spannung mehr anliegt. Das Gehäuse darf nur von qualifiziertem Wartungspersonal geöffnet werden. Dasselbe
gilt für den Austausch von FRUs.

DANGER

Ne retirez pas le capot du châssis sans avoir au préalable
débranché le cordon d’alimentation ou mis le concentrateur
hors tension. Seuls des techniciens de maintenance qualifiés
sont habilités à effectuer les opérations de dépose et de pose du
capot du châssis et des unités remplaçables.

AVISO

CAUTION

No se debe tratar de quitar la cubierta del chasis mientras
estéconectado el cable de corriente alterna o mientras haya
corriente en el contratador. Sólo personal cualificado debería
realizar la sustitución de las partes reemplazables y de la
cubierta del chasis.

Static electricity can damage modules and electronic components. Digital recommends you use a grounded wrist
strap and grounded work surface (Digital P/N 29-11762)
when you handle any modules or internal parts. (3–7)

ACHTUNG

Module und elektronische Komponenten können durch
elektrostatische Entladungen beschädigt werden. Benutzen
Sie immer eine antistatische Gelenkmans chette und eine
geerdete Arbeitsunterlage, wenn Sie am offenen Gerät
arbeiten in Antistatik-Kit ist in der BRD bei DECdirekt
unter der Bestellnummer 29-26246 erhältlich.

ATTENTION

Les charges excessives d’électricité statique peuvent endommager les modules et les composants électroniques.
Digital conseille l’utilisation d’un bracelet demasse et
d’un plan de travail mis à la terre (Réf. 29-11762) lors de
la manipulation des modules et des composants internes.

PRECAUCION

La electricidad estática puede dañar los componentes
electrónicos y los módulos. Digital recomienda que se utilicen cintas de pasadores y superficies de trabajo
conectadas a tierra (Digital P/N 29-11762) al trabajar con
cualquier módulo oparte interna.

CAUTION

Use a pointed tool to change switch settings. Never use a
pencil; graphite can damage switches. (1–3, 3–8)

ACHTUNG

Verwenden Sie einen spitzen Gegenstand, z.B. einen Kugelschreiber, wenn Sie Schaltereinstellungen ändern wollen. Benutzen Sie dazu keinen Bleistift, da der Graphitabrieb die Schalter beschädigen kann.

ATTENTION

Utilisez un outil pointu pour changer le positionnement
des commutateurs. N’utilisez jamais un crayon, car le
graphite de la mine pourrait endommager les
commutateurs.

PRECAUCION

xii

Con cualquier herramienta puntiaguda se cambian los
parámetros de conexión, pero nunca con lápices porque el
grafico daña los interruptores.

Preface

This manual describes how to troubleshoot, test, and service the DECconcentrator
500 unit. The manual contains problem-solving methods and removal and replacement procedures.
Intended Audience
This manual is for the system/network manager, as well as Digital Equipment Corporation training, services, and manufacturing personnel who have been trained to perform product maintenance and repair. Knowledge of Fiber Distributed Data Interface (FDDI) is a prerequisite to using this manual effectively.
Document Structure
This document has three chapters and three appendices:
Chapter 1

Contains information on the concentrator controls and indicators.

Chapter 2

Contains procedures to help isolate problems to a faulty
field replaceable unit (FRU).

Chapter 3

Provides removal and replacement procedures for each of
the FRUs.

Appendix A

Contains an exploded view and list of FRUs.

Appendix B

Contains concentrator specifications.

Appendix C

Contains a list of related documents.

xiii

1
Controls and Indicators

1.1 Controls and Indicators
Figure 1–1 shows the DECconcentrator 500 controls and indicators. Table 1–1 and
Table 1–2 describe the controls, connectors, and LEDs.
Figure 1–1:

Controls and Indicators

Multimode Network Management Card
optical bypass relay

Controller/backplane fault LED

Circuit breaker

Power supply DC OK LED
Connector reserved
for Digital manufacturing

AC power
Network
Management
Card
Port
Cards

Fan fault LED

OBM 25-pin
D-subminiature
connector
DECconcentratorTM 500

Network Management Card
configuration switches
Switch 1 (left): resets to factory defaults
Switch 2 (right):write access enable/disable

Ring operational LED

= Port status LED
= Fault LED
= Connectors
LKG–5114–91I

1–1

Table 1–1:

DECconcentrator 500 Controls and Connectors

Control

Description

AC power socket

For connection to an ac source.

Circuit breaker

Provides overcurrent protection for the concentrator. If the circuit
breaker trips, the white center of the circuit breaker pops out and
ac power is removed from the concentrator. Press the white center
to reset the circuit breaker.

Out-of-band management
connector

Provides remote management by allowing a connection directly to
a terminal or through a modem to a terminal.

Optical bypass connector

Provides connectivity of the FDDI ring in the absence of power or
during fault conditions in a node. The connector is located on the
Multimode Network Management Card.

Table 1–2:

DECconcentrator 500 Indicators
Color

Normal
State

Controller/backplane Fault

Red

OFF

Fan fault

Red

OFF

Power supply DC OK

Green

Red

OFF

Green/Red

Green ON

LED

Symbol

Ring operational

Ring
OK

Card fault
Port status

PHY

1.2 Network Management Switch
The Network Management Card has two software readable switches that are accessible through the front panel. The switch on the left (switch 1) is used to reset to default
control parameters that have been changed by remote management. The switch on
the right (switch 2) is used to enable or disable remote management write access
functions. The default setting for the switches is the OFF position. Figure 1–1 shows
the location of the switches. Table 1–3 lists the switch functions.

1–2

DECconcentrator 500 Problem Solving

CAUTION

Use a pointed tool to change switch settings. Never use a
pencil; graphite can damage switches.

Table 1–3:

Network Management Configuration Switch Settings

Switch
1 (Reset to
default)

Factory
Setting
OFF

Function
When set to OFF at power up, no parameters are changed, altered,
or reset.
When switch 1 is set to ON at power up, any control parameters that
have been changed through remote management (DECelms or
DECmcc) are reset to their default settings. For example, if remote
management has disabled a port, that port is no longer disabled
when you reset to the default parameters.
To reset to the default parameters, after the concentrator is installed
and operational, or after being reinstalled, do the following:

2 (Write
access enable)

OFF

Set switch 1 to ON.

Cycle the power and wait for self-test to complete.

Set switch 1 to OFF.

When set to ON, enables write access for system control parameters, such as the password and firmware upgrade.

1.3 Out-of-Band Management
The DECconcentrator 500 has an Out-of-Band Management (OBM) port that allows
the concentrator to be managed locally or remotely through a terminal. Refer to the
DECconcentrator 500 Installation manual for a description of how to use the out-ofband management feature.

Controls and Indicators

1–3

2
Troubleshooting and Testing

This chapter describes the problem-solving methods used for diagnosing and isolating a concentrator fault to the field-replaceable unit (FRU).

2.1 Tools and References
The following tools and references are recommended:

• Loopback connector (Refer to Appendix A for a list of connectors.)
• Optical power meter (P/N 29-28384-01)
• Option card installation manuals
• DECconcentrator 500 Installation manual
2.2 Problem-Solving Checklist
Before starting the problem-solving procedures and removing any attached cabling,
use the following checklist to ensure that a simple and easily overlooked problem is
not causing the concentrator fault:

• Ensure that the power cord is secure at the concentrator and power source
receptacles.

• Ensure that appropriate power is available at the electrical outlet.

2–1

•

Ensure that the circuit breaker (located on the concentrator front panel) has
not tripped. If it has, press in the white button to reset the breaker.

•

Verify that the switches on the Network Management Card are set properly
(see Section 1.2).

•

Ensure that all option cards are fully seated and locked.

•

Check that all option card modules are installed in the correct location. The
Network Management Card must be in the top slot. The Port Cards can be
installed in any slot.

•

Check that all interface cables are firmly attached.

•

Ensure that the green power supply LED is on.

2.3 Tests
To check the concentrator for normal operation or to isolate a fault, run self-test and
the loopback test, if necessary.

2.4 Self-Test
Self-test is initiated when power to the concentrator is removed and restored.
Self-test diagnostics verify that the FRUs are operating properly before the concentrator connects to the network. Visual indicators (LEDs) provide pass/fail status to
identify failed modules.
When self-test is in process the following events occur:

2–2

•

The green power supply LED, green ring operational LED, and all red fault
LEDs turn on.

•

The Network Management Card port LEDs turn red, then green, then turn off.

•

The Port Card LEDs turn red, then green, then turn off.

•

If there are no fatal errors, all red FRU indicators go out and the concentrator
becomes operational.

DECconcentrator 500 Problem Solving

•

If a non-fatal error is detected, the LED associated with the faulty port remains on, the controller/backplane fault LED turns off, and control passes to
operational firmware. Depending on the type of fault, non-fatal errors result
in either a single port being bypassed or the entire card being bypassed.

•

The fault LEDs turn off and the port LEDs blink green (if not connected).

•

The power supply and ring operational LEDs stay on.

•

If a fatal error is detected, the associated fault LED(s) remain on and the unit
is not operational.

When the operational firmware is running and the concentrator is connected to the
network, an LED next to each port indicates operational status.
2.4.1 Network Management Initiated Self-Test

The concentrator self-test can be run by software command from a host command
console by the Extended LAN Management Software (DECelms) or DECmcc. The
command sequence for self-test from the host consists of identifying the concentrator and forcing the initialization. This is equivalent to powering down and powering
up the device. See the DECelms Use or DECmcc Concentrator Access Module Use
guide for additional information.
2.4.2 Power-up Initiated Self-Test

If any ports have been disabled by remote management (DECelms or DECmcc), the
LEDs may not light as indicated in these procedures. This requires resetting the
switch on the Network Management Card to obtain the default parameters. Before
resetting the switch, notify the network/system manager. Refer to Section 1.2 for information on setting the switch.
To run self-test, apply power to the unit. The flow chart in Figure 2–1 shows the troubleshooting process. It identifies the test methods and suggested corrective action.
NOTE
When using the flow chart, start at Station A. Station B
is at the other end of the cable.

At the completion of the self-test, observe the LED display and refer to
Table 2–1through Table 2–4 to determine the appropriate course of action.

Troubleshooting and Testing

2–3

Figure 2–1:

Fault and Port Status LED Problem-Solving Flow Chart

FRU
fault LED ON
?

Yes

Replace failed FRU. If all FRU fault
LEDs are lit, replace the
controller/backplane board.

No
Port
status LED OFF
?

Yes

No
Port status
LED ON green
?

Yes

Port
state set ON
by network
management
?
No

Yes

Normal condition. End
problem solving.

Replace card (FRU).

Set port state ON
through network
management.

No
Illegal topology.
Port status
LED blinks red
?
No

Yes

Port status
LED blinks green
or red ON
?
No

Yes

Port status
LED blinks green,
red, green
?
No

Yes

2–4

Verify/reconfigure cable
connections or ring topology.

Perform loopback testing.

Port in BACKUP state.
End problem solving.

LKG–3992–90I

DECconcentrator 500 Problem Solving

Figure 2–1 (cont.): Fault and Port Status LED Problem-Solving Flow Chart

Install loopback connector
on faulty port.

Port
status LED
blinks red
?

Replace card and
retest.

Yes
Measure Tx power at the
concentrator port and Rx at
the cable input. Record
both power measurements.∗

Tx power
OK
?

Yes
Reconnect cables.

LKG–3993–90I

*Perform all transmit (Tx) power measurements at the concentrator transmit connector, not at a
patch panel. Always disconnect the receive (Rx) connector from the concentrator when measuring transmit power.

Troubleshooting and Testing

2–5

Figure 2–1 (cont.): Fault and Port Status LED Problem-Solving Flow Chart
C

Go to upstream station
at the other end of
cable. Verify operation
with steps A and B of
this flow chart.

Calculate loss. Compare
this with specification
data.

Loss
out of spec.
?

Yes

Repair/replace cable following
normal procedures.

No
Reconnect cables.

Verify that you are
checking both ends of the
same cable and have
correctly identified the
ring topology.

A
LKG–3822–90I

2–6

DECconcentrator 500 Problem Solving

2.5 Problem Solving Using the LED Indicators
This section lists typical LED displays for various error conditions, along with probable causes and suggested corrective actions.Table 2–1 describes problem solving
for the main unit, Table 2–2 for the Network Management Card, Table 2–3 for the
Port Card, and Table 2–4 for the optical bypass relay (optional).
Table 2–1:

Main Unit Problem Solving

Symptom

Probable Cause

Corrective Action

All LEDs OFF.

Circuit breaker tripped.

Reset the breaker. If the breaker continues to trip, it indicates a more serious
problem.

Power cord disconnected.

Make sure the power cord is firmly connected at both ends.

Faulty power cord.

Measure the continuity of the cord. Replace the cord if defective.

Incorrect power or no power at Check the wall outlet circuit breaker.
wall outlet.
Verify that correct power is available.
Connect the power cord to another wall
outlet.
Blown power connector fuse.

In some countries the power connector
at the wall outlet has a fuse. Replace
the fuse if necessary. If the fuse continues to blow, it indicates a more serious
problem.

DC OK LED is off and
any other LED is on.

Problem with the power
supply.

Replace or repair the power supply.

Fan LED is on (red).

Problem with the fan or fan Check the fan connector. Replace the
connection.
fan.

Controller/backplane fault LED Bad OBM card
is blinking red.

Replace OBM card.

Controller/backplane LED is on Problem with the Controller/ Check the connection to the power
(red) and all option card fault backplane, LED, or connec- supply. Replace controller/backplane
board. Rerun self-test diagnostics.
tion to the power supply.
LEDs are on (red).
Fan LED blinking.

Incompatible hardware/
Load the latest firmware.
firmware (firmware version is
2.3 or below, backplane hardware revision is 1 or higher*).

* The hardware revision number of the backplane can be read by the network management software as an attribute under a table column called FRU Revision. Refer to the documentation for
your particular management software for details.

Troubleshooting and Testing

2–7

Table 2–2:

Network Management Card Problem Solving

Symptom

Probable Cause

Corrective Action

Card Fault LED on (red); other Problem with the Network
Port Card LEDs off; unit LEDs Management Card.
are normal.

Replace the Network Management
Card.

Card Fault LED blinking red.

Network Management Card is Install the Network Management Card
installed in the wrong slot
in the top slot (A).
(B or C).

Ring Operational LED off.

Network is not operational or Verify activity on network. Replace Netproblem with Network Man- work Management Card.
agement Card.

Port LED off.

Port disabled by management, Enable port through the management
Bad LED or faulty card.
software. Otherwise, use the reset to
default parameter switch (and notify
the network manager that you are resetting the parameters). Replace the
card

Port LED blinking red.

Unsupported configuration or Notify your network manager. Reconfiring topology, or loopback con- gure the cable connections or ring tonector installed.
pology.

Port LED blinking green

Unable to connect; no cable at- Check cable connections. Run looptached.
back test described in Section 2.6 to
test the port. See Table 2–5 for problem
solving during loopback testing.

Port LED red and
card fault LED off.

Link Confidence Test (LCT)
Check the cable connections. Run the
failure. Possible cable or cable loopback test to verify the port.
connection problem.

Port LED red and
card fault LED on.

Port in broken state.

Replace the card.

Port LED alternates red
and green (port A only).

Port is in backup state.

No corrective action is required. The
backup link becomes active if the primary link fails.

Table 2–3:
Symptom

Port Card Problem Solving
Probable Cause

Corrective Action

A Card Fault LED is on (red), Problem with the Port Card.
other Port Card LEDs are off,
and unit LEDs normal.

2–8

The card needs to be replaced or repaired. Notify your system/network
manager or service provider.

DECconcentrator 500 Problem Solving

Port LED off.

Port LED blinking red.

Unsupported configuration or Notify your network manager. Reconfiring topology.
gure the cable connections or ring topology.

Port LED blinking green

Connection in progress

Connection may take up to 1 minute to
achieve. LED remaining in this state
may be caused by very poor signal.
Make sure the cable is fully connected
and the connecting unit on the far end
is powered up. If LED is still blinking
green, perform the loopback test, as
described in Section. 2.6.

Port LED red and card
fault LED on.

Port broken.

Port LED red and card
fault LED is off.

Link Confidence Test (LCT) Check cable connections. Run the
failure, possible cable or cable loopback test described in Section 2.6
connection problem.
to test the port. See Table 2–5 for problem solving during loopback testing.

Port LED alternates red
and green.

Port is in backup state.

Table 2–4:

The card needs to be replaced or repaired. Notify your system/network
manager or service provider.

No corrective action is required. The
backup link becomes active if the primary link fails.

Optical Bypass Relay Problem Solving

Symptom

Probable Cause

Corrective Action

DECconcentrator 500 is OK but Optical bypass relay is stuck in Verify by removing the relay and obcannot communicate with the the bypass position or RJ12 serving that communications among all
dual ring.
connector is not plugged in.
stations is re-established. Replace the
relay.
Upstream and downstream stations are wrapped when the concentrator is powered down or
the controller/backplane LED is
red.

Troubleshooting and Testing

1. Optical bypass relay is stuck 1. Replace the relay.
in the inserted position.
2. Excessive loss induced by 2. Ensure that the link loss induced by
the optical bypass relay.
the relay does not cause the total interstation loss to exceed 11 dB. (Refer to
the FDDI Network Configuration
Guidelines manual.)

2–9

2.6 Loopback Testing
Perform loopback testing when LEDs indicate port faults on either the Port or Network Management Cards. Do this by using a loopback connector, which routes the
transmitter output back into receiver. This test is used to discriminate between faults
originating at the concentrator and those caused by the network or by devices on the
network.
This test verifies the basic ability to transmit and receive. However, it does not verify
the ability to receive minimum level signals or that the transmitter’s output level is
within specification.
To perform loopback testing, follow these steps:
1. Refer to the option card installation manual for the type of loopback connector to use.
2. Install the loopback connector in the port to be tested.
3. Observe and record the port LED status on the port where the loopback connector is installed. Normal operation for this LED is to blink red (indicating
an illegal configuration).
4. Refer to Table 2–5 for corrective action.
Table 2–5:

Problem Solving During Loopback Testing

Symptom

Probable Cause

Corrective Action

Port LED red ON, green ON,
or blinking green.

Port failure.

Replace the Port card
for that port.

Port LED blinking red.

Normal during loopback
testing.

No action required.

2.7 Measuring the Optical Power
If a failure in a port disappears when a loopback test is performed, check the optical
signals into and out of the port to determine if they are within specifications. To measure the power levels of the transmit and receive optical signals at the concentrator,
use the SDU optical power meter kit (P/N 29-28384-01). This kit contains an optical
power meter, a receive cable, and cleaning pads. To make the measurements, use the
following steps:

2–10

DECconcentrator 500 Problem Solving

NOTE
If measuring power at a simplex connector (ST), both
the transmit and receive cables must be disconnected to
get a proper light-signal pattern and observe correct
power readings.

1. Set up the optical power meter as follows:
a. Remove the protective cap from the input test head.
b. Turn on the meter by pressing the ON/OFF switch.
c. Use the λ select switch to select the 1300-nm wavelength range. The
wavelength value will appear on the LCD display.
2. To ensure a clean test connection, remove the protective caps from the test
cable connectors and use a cleaning pad to wipe the connector faces.
3. To measure the power of the fiber optic signal transmitted by the concentrator
port, refer to Figure 2–2 and follow these steps:
a. Connect the FDDI connector end of the receive cable to the port receptacle on the concentrator.
b. The other end of the receive cable has two leads (and fiber optic connectors). The lead with the arrow pointing towards the connector carries the
transmit signal from the concentrator. Plug this lead into the test head of
the meter.
c. The power level of the transmit signal will be displayed on the meter’s
LCD display. Record the value in Table 2–6.
d. Disconnect the receive cable from the concentrator and from the meter.

Troubleshooting and Testing

2–11

Figure 2–2:

Measuring the Transmit Power (Multimode)

Tester
(receive)
cable

Transmit signal
from concentrator

On/Off
Wavelength
select
LKG–5196-91I

2–12

DECconcentrator 500 Problem Solving

4. To measure the power of the fiber optic signal received by the concentrator,
refer to Figure 2–3 and follow these steps:
a. Move the power meter close to the FDDI cable that normally plugs into
the port of the concentrator.
b. Plug the output connector on that cable into the test head of the meter.
(Note: The output connector is the smaller of the two connectors on the
cable.)
c. The power level of the receive signal will be displayed on the meter’s
LCD display. Record the value in Table 2–6.
NOTE
If there is no reading when you perform step 4.-c, you
could be checking the wrong connector (that is, the input
connector rather than the output). If this occurs, measure
power at the other connector.

Table 2–6 shows a sample table that you can use to record the receive and
transmit power for the concentrator (station A) and for the upstream device (station B). You can also use the table to record the cable loss between the two stations (the transmit power at one station minus the
receive power at its downstream station).

Troubleshooting and Testing

2–13

Figure 2–3:

Measuring the Receive Power (Multimode)

Normal
connection

FDDI cable
to concentrator
Receive signal
to concentrator

LKG–5195-91I

2–14

DECconcentrator 500 Problem Solving

5. Check the recorded values against the specifications given below. If either
measurement falls outside the given range, that optical signal is not within
specifications. Refer to the flow chart in Figure 2–1 for recommended corrective actions.
ANSI multimode (using 62.5-µm multimode fiber cable):
–

Power level of the transmit signal: –20 dBm to –14 dBm (max)

–

Power level of the receive signal:

–31 dBm to –14 dBm (max)

Low-power multimode (using 62.5-µm multimode fiber cable):
–

Power level of the transmit signal: –22 dBm to –14 dBm (max)

–

Power level of the receive signal:

–29 dBm to –14 dBm (max)

Single-mode:
–

Power level of the transmit signal: –8.0 dBm to –2.5 dBm (max)

–

Power level of the receive signal:

Table 2–6:

–30 dBm to –14 dBm (max)

FDDI Transmit and Receive Power Calculation

Tx Power

STA

__________ dBm

STB

__________ dBm

Rx Power

STB

__________ dBm

STA

__________ dBm

Loss

Troubleshooting and Testing

__________ dBm

2–15

3
Removal and Replacement Procedures

This chapter contains the removal and replacement procedures for the concentrator
FRUs.
WARNING

Disconnect the ac power cord before removing any
field-replaceable units. Do not apply power to the concentrator unless all covers are installed. Only qualified
service engineers should perform any of these removal
and replacement procedures.
WARNING

Some fiber optic equipment emits laser light that can injure your eyes. Never look into an optical fiber or connector port. Always assume that the cable is connected
to a light source.

3.1 Preparing the Concentrator for Servicing
The concentrator can be a desktop unit or rackmounted. The Network Management
Card and Port Card(s) can be installed or removed without removing the plastic enclosure (for desktop models) or removing the concentrator from the rack. If the concentrator is a desktop unit, remove the plastic enclosure before servicing the internal
FRUs. If the concentrator is rackmounted, remove it from the rack before servicing
the internal FRUs.

3–1

The steps in Section 3.1.1 explain how to remove and replace the plastic enclosure
from a desktop model. The steps in Section 3.1.2 explain how to remove and replace
the concentrator from a rackmount.
3.1.1 Removing and Replacing the Plastic Enclosure

Desktop units have a plastic cover (top, bottom, and side spacers) and rubber feet that
you must remove to access the main unit.
To remove the plastic enclosure, perform the following steps:
1. Remove power to the concentrator by unplugging the power cord from the
wall outlet and then from the concentrator.

WARNING !
Always remove the power cord from the concentrator
and ac source when performing any removal and replacement procedures. Also remove any port cable connectors when servicing the concentrator.

2. Record the location and cable tag number of each port cable. Note the orientation of each cable and remove all port cables.

NOTE
Reinstall all cables back in their original ports and position; an incorrectly installed cable can cause the network to fail.

3. Turn the unit upside down and remove the four rubber feet screws as shown
in Figure 3–1. (These screws also hold the top plastic cover and side spacers
in place.)

NOTE
The top and bottom of the enclosure have arrows imprinted on the inside to help with the reassembly. The arrows indicate the front of the unit.

4. Remove the four bottom cover screws as shown in Figure 3–1.

3–2

DECconcentrator 500 Problem Solving

5. Lift the bottom cover up and off, remove the side spacers, and lift the concentrator up and away from the top cover.
6. Save all removed hardware for later reinstallation.
To reinstall the plastic cover, reverse steps 1–5.
Figure 3–1:

Plastic Enclosure Removal and Replacement
Screws for feet
Rubber feet

Screws to chassis

Spacer

LKG–3804–90I

Removal and Replacement Procedures

3–3

3.1.2 Removing and Replacing a Rackmount Unit

To remove the concentrator from a rackmount, perform the following steps:
1. Remove power to the concentrator by unplugging the power cord from the
wall outlet and then from the concentrator.

2. Record the location and cable-tag number of each port cable. Note the orientation of each cable and remove all port cables.

NOTE
Make sure to reinstall all cables back in their original
ports and position; an incorrectly installed cable can
cause the network to fail.

3. Support the unit and remove the four rackmount screws as shown in
Figure 3–2.
4. Remove the unit from the rack.
5. Place the concentrator on a clean flat surface.
6. If necessary, remove the rackmount brackets by removing the six bracket
screws as shown in Figure 3–3.
7. Save all removed hardware for later reinstallation.
To install the concentrator in a rack, reverse steps 1–6.

3–4

DECconcentrator 500 Problem Solving

Figure 3–2:

Rackmount Unit Removal and Replacement

Front of cabinet

(4) 10–32
Phillips-head screws
with (4) lock washers
NOTE:
Always leave 2.54 cm (1 in) of space between
mounted devices for passing cables to the back of the rack.
LKG–3807–91l

Removal and Replacement Procedures

3–5

Figure 3–3:

Rackmount Bracket Removal and Replacement

LKG–3805–91I

3.2 Removing and Replacing Concentrator FRUs
This section describes how to remove option cards and how to remove the metal
chassis cover to gain access to the concentrator internal FRUs. Options cards are removed directly from the concentrator and do not require the removal of any covers
for access. Internal FRUs require the removal of the metal chassis cover. Once the
chassis cover is removed, follow the appropriate procedure for the FRU to be replaced.

3–6

DECconcentrator 500 Problem Solving

The major concentrator FRUs are:

•

Option cards (Network Management and Port Card—all variations)

Internal FRUs:

•

Controller/backplane board

•

Fan

•

Power supply

•

OBM card and cable assembly

Additional procedures are included for the following replaceable items:

•

Power connector and filter

•

Circuit breaker removal

A Phillips-head screwdriver is required to perform the removal and replacement procedures.

WARNING !
Do not attempt to remove any of the field-replaceable
units (including the option cards) while the ac power
cord is connected or while there is power to the concentrator (ON). Safety regulations require all covers to be
installed before applying power to the concentrator. Removal and installation of the field-replaceable units
should only be performed by qualified service personnel.

CAUTION

Static electricity can damage modules and electronic
components. Digital recommends you use a grounded
wrist strap and grounded work surface (Digital P/N
29-11762) when you handle any modules or internal
parts.

Removal and Replacement Procedures

3–7

3.2.1 Removing and Replacing Option Cards

Options cards are removed directly from the concentrator and do not require the removal of any covers. Rackmount units do not need to be removed from the rack to
replace the option cards.
Several versions of the Network Management Card and the Port Card exist. Make
sure that you replace a defective card with an identical card. Refer to the option card
version identification on the left side of the handle.

NOTE
The Network Management Card contains two switches.
Set the switches on the replacement card to match the
card you removed. (See Section 1.2 for information on
location and setting the switches.)

NOTE
Follow the directions in Section 2.4.2 when you are
ready to reapply power to the unit.

CAUTION

Use a pointed tool to change switch settings. Never use a
pencil; graphite can damage switches.

To remove an option card, perform steps 1–5.
1. Remove power to the concentrator by unplugging the power cord from the
wall outlet and then from the concentrator.
2. Record the location and cable tag number of each port cable being removed.
Note the orientation of each cable and remove all port cables from the option
card.
3. Push in each option card handle captive screw and rotate it 1/4 turn counterclockwise to release as shown in Figure 3–4.
4. Unlock the option card locking levers.
5. Pull the option card straight out.

3–8

DECconcentrator 500 Problem Solving

Figure 3–4:

Option Card Removal and Replacement

1/4 turn

Locked

Unlocked
LKG–3802–91I

Removal and Replacement Procedures

3–9

To replace an option card, perform steps 6–9.
6. Place the option card locking levers in the unlocked position (swung outward) and slide the card into the slot until it makes contact with the controller/backplane board connectors.
7. Push the option card locking levers inward to lock the card in place.
8. Push in each option card handle captive screw and rotate it 1/4 turn clockwise
to secure the card.
9. Connect the interface cables and the power cord when you complete the installation.
3.2.2 Opening the Chassis Cover

Before opening the chassis cover, ensure that the concentrator is prepared for servicing by following the instructions in Section 3.1.

WARNING !
Do not attempt to remove the chassis cover while the ac
power cord is connected or while there is power to the
concentrator. Chassis cover and field-replaceable unit
removal should only be performed by qualified service
personnel.

Open the metal chassis cover (make sure that the ESD wrist strap is attached) by performing the following steps:
1. Remove the four top chassis screws as shown in Figure 3–5.
2. Remove the 14 end screws shown Figure 3–5. (On a rackmounted unit, you
removed six of these screws when you removed the rackmount brackets.)
3. Lift the chassis cover off.
4. Save all removed hardware for later reinstallation.

3–10

DECconcentrator 500 Problem Solving

Figure 3–5:

Chassis Cover Removal and Replacement

LKG-3981-91l

Removal and Replacement Procedures

3–11

3.2.3 Removing and Replacing the OBM Card

Before beginning this procedure, refer to Section 3.1 for instructions on preparing
the concentrator for servicing, and to Section 3.2.2 for instructions on removing the
chassis cover.
To remove the OBM card, perform the following steps:
1. Disconnect the OBM cable from the backplane connector.
2. Remove the two hex screws that attach the OBM card to the I/O panel, as
shown in Figure 3–6.
3. Remove the OBM card and cable assembly from the concentrator.
4. Save the screws for later reinstallation.
To install an OBM card, reverse steps 1 – 3.

3–12

DECconcentrator 500 Problem Solving

Figure 3–6:

OBM Card Removal and Replacement

OBM cable
OBM card

Hex screws

LKG-5707-91l

Removal and Replacement Procedures

3–13

3.2.4 Removing and Replacing the Controller/Backplane Board

Refer to Section 3.1 for detailed instructions on preparing the concentrator for servicing. Refer to Section 3.2.2 for instructions on removing the chassis cover.
To remove the controller/backplane board, perform the following steps:
1. Remove all option cards.
2. Disconnect the OBM cable from its backplane connector as shown in
Figure 3–6.
3. Remove the two controller/backplane board screws from the card cage posts
as shown in Figure 3–7.
4. Disconnect the controller/backplane board from the power supply by gently
pushing the top edge of the card away from the power supply.
5. To remove the controller/backplane board, lift the card straight up from the
chassis.
6. Save all removed hardware for later reinstallation.
To install a controller/backplane board, reverse steps 1–5.

3–14

DECconcentrator 500 Problem Solving

Figure 3–7:

Controller/Backplane Board Removal and Replacement

1
2

LKG-3982-91I

Removal and Replacement Procedures

3–15

3.2.5 Removing and Replacing the Fan

This section describes how to remove the concentrator fans. Both fans are replaced
as an assembly.
Before beginning this procedure, refer to Section 3.1 for instructions on preparing
the concentrator for servicing, and to Section 3.2.2 for instructions on removing the
chassis cover.
To remove the fan assembly, perform the following steps:
1. Remove the chassis cover as described in Section 3.2.
2. Disconnect the two 3-pin fan connectors from the power supply as shown in
Figure 3–8.
3. Remove the two fan restraining screws as shown in Figure 3–8 and lift the
assembly straight up.
4. Save all removed hardware for later reinstallation.
To install a fan assembly reverse steps 1–3.

3–16

DECconcentrator 500 Problem Solving

Figure 3–8:

Fan Removal and Replacement

2
LKG-3983-91I

Removal and Replacement Procedures

3–17

3.2.6 Removing and Replacing the Power Supply

This section describes how to remove the concentrator power supply.
Before beginning this procedure, refer to Section 3.1 for instructions on preparing
the concentrator for servicing, and to Section 3.2.2 for instructions on removing the
chassis cover.
To remove the power supply perform the following steps:
1. Remove the controller/backplane board as described in Section 3.2.4 to allow
access to the power supply.
2. Disconnect the OBM cable from the OBM card and remove the cable.
3. Disconnect the two 3-pin fan connectors from the power supply as shown in
Figure 3–8.
4. Disconnect the blue and brown lead wires from the circuit breaker and line
filter as shown in Figure 3–9.
5. Remove the five power supply screws from the card cage as shown in
Figure 3–9.
6. Lift the power supply straight up and out of the cage.
To install a power supply, reverse steps 1–6.

3–18

DECconcentrator 500 Problem Solving

Figure 3–9:

Power Supply Removal and Replacement

LKG-3985-91l

Removal and Replacement Procedures

3–19

3.2.7 Removing and Replacing the Power Connector and Filter

This section describes how to remove the concentrator power connector and filter.
Before beginning this procedure, refer to Section 3.1 for instructions on preparing
the concentrator for servicing, and to Section 3.2.2 for instructions on removing the
chassis cover.
To remove the power connector and filter, perform the following steps:
1. Disconnect the green/yellow grounding strap from the chassis, and the blue
and brown lead wires from the filter as shown in Figure 3–10.
2. Remove the two power connector and filter screws as shown in Figure 3–10.
3. Pull the power connector and filter out from the unit.
To install a power connector and filter, reverse steps 1–3.

3–20

DECconcentrator 500 Problem Solving

Figure 3–10: Power Connector and Filter Removal and Replacement

LKG-3987-91I

Removal and Replacement Procedures

3–21

3.2.8 Removing and Replacing the Circuit Breaker

This section describes how to remove the concentrator circuit breaker.
Before beginning this procedure, refer to Section 3.1 for instructions on preparing
the concentrator for servicing, and to Section 3.2.2 for instructions on removing the
chassis cover.
To remove the circuit breaker, perform the following steps:
1. Disconnect the two brown lead wires from the circuit breaker as shown in
Figure 3–11.
2. Remove the circuit breaker nut and washer as shown in Figure 3–11.
3. Push the circuit breaker away from the panel and remove.
To install a circuit breaker, reverse steps 1–3.

3–22

DECconcentrator 500 Problem Solving

Figure 3–11: Circuit Breaker Removal and Replacement

LKG-3987-91I

Removal and Replacement Procedures

3–23

3.3 Reassembling and Reinstallating the Concentrator
To reassemble the concentrator, perform steps 1–4.
1. Carefully replace the chassis cover onto the bottom of the chassis.
2. Reinstall the 18 screws on the sides and top of the unit. Note that four
flathead screws go on the top of the chassis and should be reinstalled first to
help with the cover alignment. Six of the side screws hold the rackmounting
brackets, which should be installed at this time.
3. Reinstall the option cards.
4. Test the unit for proper operation by following the procedures contained in
Chapter 2.
To reinstall the concentrator, perform step 5 or 6.
5. If the unit is a desktop model, reinstall the plastic enclosure by following the
instructions in Section 3.1.1. Note that the unit is shown upside down so that
the rubber feet and screws can be reinstalled. Connect all cables and verify
the installation by referring to the DECconcentrator 500 Installation manual.

NOTE
The top and bottom of the enclosure have arrows
imprinted on the inside to help with the reassembly.
The arrows indicate the front of the unit.

6. If the concentrator is rackmounted, reinstall the unit by following the instructions in Section 3.1.2. Verify the reinstallation by referring to the
DECconcentrator 500 Installation manual.

3–24

DECconcentrator 500 Problem Solving

A
Parts List

Figure A–1 is an exploded view of the concentrator modular components.
Table A–1 lists the FRUs and their Digital part numbers.
Refer to the DECconcentrator 500 Illustrated Parts Breakdown manual for
additional information on part numbers.

A–1

Figure A–1: DECconcentrator 500 FRUs

*Top plastic
cover

*Top metal
chassis

Fan assembly

Controller/Backplane
OBM card & cable
Power supply
Network Management
Card
Port card

*Bottom metal
chassis

*Not an FRU
*Bottom plastic
cover
LKG-5708-91l

A–2

DECconcentrator 500 Problem Solving

Table A–1:

DECconcentrator 500 Parts List

Part

Digital Part Number

Controller/backplane board

54-19379-01

OBM card

54-19449-01

OBM cable

17-03347-01

Network Management Card (DEFCN-MA)

54-19383-01

Network Management Card (DEFCN-EA)

54-19383-02

Network Management Card (DEFCN-CA)

54-19383-03

Network Management Card (DEFCN-DA)

54-19383-04

Port Card (DEFCN-NA)

54-19381-01

Port Card (DEFCN–LA)

54-19393-01

Port Card (DEFCN-FA)

54-19381-02

Port Card (DEFCN-SA)

54-19431-01

Port Card (DEFCN-TA)

54-19425-01

Dual fan assembly

70-26996-01

Power supply

H7855-A

Circuit breaker assembly

12-19912-02

Power connector/filter assembly

12-32976-01

Blank handle

70-26994-01

Subassembly, base (chassis)

70-26993-01

Assembly, cover (chassis cover)

70-26727-01

Plastic enclosure bottom

74-32072-03

Plastic enclosure spacer

74-32246-01

Plastic enclosure top

74-32072-01

Rackmount brackets

H041-AE

Fiber optic loopback connector

12-32005-01

Low power loopback connector

17-02970-01

Single-mode loopback connector

12-34830-01

STP loopback connector

12-35629-01

ThinWire loopback connector

12-35621-01

Antistatic service kit

29-11762

Parts List

A–3

B
Specifications

This section contains the DECconcentrator 500 physical, electrical, and environmental specifications.

B.1 Physical Specifications
The DECconcentrator 500 is available as either a rackmounted or desktop unit. The
physical dimensions are detailed in Table B–1.
Table B–1: Physical Specifications
Rackmounted Unit

Desktop Unit

Height 13.4 cm (5.3 in)

Height 16.1 cm (6.3 in)

Depth

29.9 cm (11.8 in)

Depth

31.4 cm (12.3in)

Width

43.6 cm (17.2 in)

Width

49.3 cm (19.4 in)

Weight

7.9 kg (17.5 lbs)

Weight 10 kg (22 lbs)

B–1

B.1.1 Environmental Specifications

The DECconcentrator 500 operates in an open office environment, equipment room,
or in an exposed area of an industrial site. The DECconcentrator 500 is not designed
for operation in an air plenum. The environmental specifications are detailed in
Table B–2.
Table B–2: Environmental Specifications
Parameter

Specification

Operating Environment:
Temperature (at sea level)*

5° C (41° F) to 35° C (95° F) – with plastic enclosure
5° C (41° F) to 50° C (122° F) – without plastic enclosure

Relative humidity

10% or less to 95% (noncondensing)

Wet bulb

32° C (90° F) maximum

Dew point

2° C (36° F) minimum

Altitude

Sea level to 2.4 km (8000 ft)

Air flow

200 LFM (minimum). For adequate airflow, provide about
10 to 15 cm (4 to 6 in) of space at both ends

Inlet/outlet air temperature

Inlet: 50° C (122° F) maximum
Outlet: 60° C (140° F) maximum

Shipping Environment:
Temperature

–40° C (–40° F) to 66° C (151° F)

Relative humidity

10% or less to 95% (noncondensing)

Altitude

Sea level to 9.1 km (30,000 ft)

*Reduce the maximum operating ambient temperature by 1.8° C/1000 m (or 1° F/1000 ft) for operation
at high-altitude sites.

B–2

DECconcentrator 500 Problem Solving

B.1.2 Electrical Specifications

The DECconcentrator 500 operates at 120 Vac or 220/240 Vac. The electrical specifications are detailed in Table B–3. Details on the internal power supply are contained in Table B–4.
Table B–3: Electrical Specifications
Parameter

120 Vac Operation

220/240 Vac Operation

Line voltage

110 V

220 V

Voltage tolerance

88 Vac to 132 Vac

176 Vac to 264 Vac

Power source phasing

Single

Frequency

50/60 Hz

Line frequency tolerance

47 Hz to 63 Hz

Input current (typical)

1.6 ARMS at 88 VRMS line

0.92 ARMS at 176 RMS line

Input current (maximum)

2.3 ARMS at 88 VRMS line

1.2 ARMS at 176 RMS line

Input power (typical)

105 W (input VA 155 maximum) 105 W (input VA 177 maximum)

Input power (maximum)

120 W (input VA 200 maximum) 120 W (input VA 200 maximum)

Overvoltage condition

150 VRMS for 1 second
maximum

300 VRMS for 1 second
maximum

Cold start inrush current

Low range: 35 A peak
High range: 35 A peak

Heat dissipation (typical)

105 W

Heat dissipation (maximum)

120 W

Specifications

B–3

B.2 Power Supply
The DECconcentrator 500 power supply is a 154-watt, open-frame, low-noise offline switching power supply. The outputs are listed in Table B–4.
Table B–4: Power Supply Specifications
Voltage

Current

Maximum Current*

+5.1 Vdc

18 A

25 A

+12.0 Vdc

2.5 A

–5.2 Vdc

10 A

15 A

* The maximum power output of the supply is 154 watts. The maximum currents listed for
the individual supplies can be drawn, provided the sum of the currents does not exceed the
total power output of the supply.

The power supply automatically shuts down if any of the following conditions occur:

•

Improper Output
–

If an overcurrent condition occurs on either the +5.1 Vdc or –5.2 Vdc
output, the power supply output becomes latched and will not automatically recover even if the cause of the overcurrent condition is removed.
To reset the supply and resume normal operation, you must cycle power
by removing ac power to the unit, waiting at least 10 seconds, then reapplying the ac power.
With the proper cooling, the outputs are capable of operating indefinitely
into a short circuit.
If an overcurrent condition occurs on the +12 Vdc output none of the other outputs will be affected. The supply will automatically recover when
the cause of the overcurrent is removed. The output current of the +12
Vdc must be less than 5 amperes after 1 minute.

•

Overvoltage Protection
–

B–4

If an overvoltage condition occurs on any of the outputs, the power supply becomes latched. To reset the supply and resume normal operation,
you must remove ac power, wait 10 seconds, then reapply the ac power.

DECconcentrator 500 Problem Solving

•

Thermal Protection
–

•

The maximum inlet temperature must not exceed 50° C (122° F). If cooling air is lost and the unit operating temperature exceeds 50° C (122° F),
the power supply protects itself by shutting down. Just prior to shutting
down, the power supply deasserts POK to alert the system of the impending shutdown. After the problem has been corrected, the power supply
must be reset by recycling ac power as described in the previous paragraph .

Auto-voltage select
–

This feature permits operation at 110/120 Vac or 220/240 Vac without
setting a voltage selection switch.

B.3 Fiber Cable Specifications
Table B–5 and Table B–6 list multimode fiber optic cable specifications.
Table B–5: Multimode Fiber Cable Specifications
Recommended Cable

Parameters

Core diameter

62.5 ± 3.0 µm

Cladding diameter

125.0 ± 2.0 µm

Nominal operating wavelength

1300 nm

Nominal aperture

0.275 ± 0.015

Zero dispersion slope

0.110 ps/(nm2• km), maximum

Optical power attenuation

≤ 1.5 dB/km @ 1300 nm

Minimum power budget

11.0 dB @ 1300 nm

Minimum bandwidth

500 MHz• km

Maximum distance

2 km (1.2 mi.)

Specifications

B–5

Table B–6: Alternate Multimode Fiber Cable Specifications
Alternate Cable

100/140

50/125

Nominal core diameter

100 µm* ± 4.0 µm

50 µm* ± 3.0 µm

Nominal cladding diameter

140 µm* ± 6.0 µm

125 µm* ± 2.0 µm

Nominal operating wavelength 1300 nm

1300 nm

Nominal numerical aperture

0.290 ± 0.02

0.200 ± 0.02

Minimum bandwidth

500 MHz• km

Minimum power budget

11 dB

6.0 dB

Maximum distance

1.6 km (0.96 mi.)

2 km (1.2 mi.)

* Power budget depends on core and cladding tolerances.

NOTE
Lengths less than 1 km (0.6 mi.) of 100 micron fiber do not
have sufficient optical loss. Malfunction of the receiver can
occur. Use 62.5/125 patch cords to induce loss.

The FDDI single-mode PMD standard (currently under development) describes the
characteristics of single-mode fiber for long-distance links. Table B–7 lists the single-mode fiber optic cable specifications.
Table B–7: Single-Mode Fiber Cable Specifications

B–6

Recommended Cable

Parameters

Mode Field diameter

8.2 µm to 10.5 µm

Cladding diameter
Fiber cladding noncircularity

125 µm ± 2 µm
2% maximum

Core to cladding concentricity error

1 µm maximum

Nominal operating wavelength

1300 nm

Fiber cutoff wavelength

1270 nm maximum

Zero dispersion wavelength

1300 to 1322 nm

Zero dispersion slope

0.095 ps/(nm2• km) maximum

Optical power attenuation

≤ 0.40 dB/km @ 1310 nm

Power budget
Minimum required loss

22 dB
12 dB

Maximum distance

40 km (24 miles)

DECconcentrator 500 Problem Solving

B.4 General Specifications for ThinWire and Shielded Twisted-Pair
Cable
The cableplant meets the following parameters:

•

The maximum cable length is 100 meters.

•

The link has a maximum of two patch cables: a crossconnect cable and a nonspliced behind-the-wall cable.

•

The cable is continuous, without any taps or junctions.

Cable configurations conform to the EIA/TIA-568 building wiring standard, which
states that the horizontal is limited to a maximum of 90 meters, including a maximum
of 3 meters in the work area, and a maximum of 6 meters for cross-connecting.

B.5 ThinWire Cabling Specifications
The ThinWire cableplant should meet the following:

•

The ThinWire/10base2 50-ohm coaxial cable must conform to the IEEE
802.3 standard.

•

The loss must be less than 11.5 dB measured at 62.5 MHz with a HewlettPackard HP4195A or equivalent network analyzer.

•

Cables must be installed in accordance with the typical installation guidelines
specified by the vendors of each cable type.

B.6 Shielded Twisted-Pair Cabling Specifications
Verify that each cableplant meets the following parameters:

•

Cabling must be installed and verified to conform to the IEEE 802.5 token
ring network installation guidelines.

•

Cables must be installed in accordance with the typical installation guidelines
specified by the vendors of each cable type.

•

The loss must be less than 12 dB measured at 62.5 MHz.

Specifications

B–7

C
Related Documents

Refer to the following documents for additional information about the DECconcentrator 500 and other associated FDDI products. Information for ordering the documents is at the back of this manual.

•

DECconcentrator 500 Installation (Order No. EK–DEFCN–IN)
This manual describes how to configure and install the DECconcentrator 500.

•

DECconcentrator 500 Multimode Option Card Installation
(Order No. EK–DEFCN–MM)
This manual describes how to install additional or replacement multimode
option cards in the DECconcentrator 500.

•

DECconcentrator 500 Single-mode Option Card Installation
(Order No. EK–DEFCN–SM)
This manual describes how to install additional or replacement single-mode
option cards in the DECconcentrator 500.

•

DECconcentrator 500 ThinWire and Shielded Twisted-Pair Option Card
Installation (Order No. EK–DEFCN–CM)
This manual describes how to install ThinWire and shielded twisted-pair option cards in the DECconcentrator 500.

C–1

•

DECconcentrator 500 Illustrated Parts Breakdown
(Order No. EK–DEFCN–IP)
This manual shows all the parts of the concentrator and lists the part order
numbers.

•

DECbridge 500/600 Installation and Upgrade (Order No. EK–DEFEB–IN)
This manual describes how to install or upgrade the DECbridge 500/600
series.

•

DECbridge 500/600 Problem Solving (Order No. EK–DEFEB–PS)
This manual describes how to isolate faults in the DECbridge 500/600 series
to the field-replaceable unit (FRU), and also how to remove and replace each
FRU. This is a field problem-solving manual.

•

DECconnect System Fiber Optic Planning and Configuration
(Order No. EK–DECSY–FP)
This manual describes the planning requirements, product information, and
guidelines for configuring DECconnect system fiber optic networks that use
DECconnect system fiber optic products.

•

DECconnect System Fiber Optic Installation (Order No. EK–DECSY–FI)
This manual describes how to install a DECconnect system fiber optic plant.

•

DECelms Installation (Order No. AA-PAK1A-TE)
This manual describes how to install and verify DECelms (DEC Extended
LAN Management Software) on a VMS system.

C–2

DECconcentrator 500 Problem Solving

•

DECelms Use (Order No. AA–PAK2A–TE)
This manual describes how to use DECelms to configure, manage, and monitor the LAN Bridge 100, LAN Bridge 150, LAN Bridge 200, DECbridge 500,
and DECconcentrator 500.

•

DECelms Reference (Order No. EK–PBWBA–TE)
This is a reference guide to the DECelms commands.

•

DECmcc Installation (Order No. AA-PD58-BTE)
This manual describes how to plan and install the DECmcc Extended LAN
Manager software.

•

DECmcc Concentrator Access Module Use (Order No. AA-PH31A-TE)
This manual describes the DECconcentrator 500 entity model, entity management, and the directives necessary to perform typical management operations.

•

Fiber Distributed Data Interface System Level Description
(Order No. EK–DFSLD–SD)
This manual describes the FDDI system, how it works, and the role of the
individual components.

•

Fiber Distributed Data Interface Network and Configuration Guidelines
(Order No. EK–DFDDI–CG)
This manual describes the guidelines for connecting devices to an FDDI network. It also includes network configurations and examples.