TM-9-2350-311-20-2

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS

DECEMBER 1993

TM-9-2350-311-20-2 - Page 218 of 828

TM 9–2350–311–20–2

3–106

3–3

TROUBLESHOOTING — CONTINUED

i.

INTERCOMMUNICATION SYSTEM

— CONTINUED

(2)

AMPLIFIER AM1780/VRC DOES NOT KEY

WHEN MIC BUTTON IS PUSHED.

INITIAL SETUP

Tools

Artillery and turret mechanic’s tool kit

(SC 5180–95–CL–A12)

Equipment Condition

Vehicle MASTER switch to OFF (TM 9–2350–311–10)

Amplifier AM 1780/VRC POWER switch to OFF

(TM 9–2350–311–10)

1.

Disconnect cable CX4723 from J506 connector

at amplifier AM 1780/VRC.

2.

Turn MASTER and amplifier AM 1780/VRC

POWER switches to ON.

3.

Place a jumper wire in socket H and socket A

of J506 connector.

4.

Repeat steps 1. through 3. for connectors

J507, J505, J510, and J504.

Is a clicking noise heard in amplifier AM 1780/VRC for

each test?

yes

no

A

Replace amplifier AM

1780/VRC (para 8–16).

Troubleshoot faulty control

box circuit (para 3–3i.).

END OF TASK

J507

J506

J505

J504

J510

AMPLIFIER

AM 1780/VRC

J506, J507, J505, J510,

OR J504 CONNECTOR