TM-9-2350-274-BD

M109/M110/M578 VEHICLES HOWITZER, MEDIUM, SELF-PROPELLED FULL-TRACKED

TECHNICAL MANUAL; OPERATORS, ORGANIZATIONAL DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE

JANUARY 1984

TM-9-2350-274-BD - Page 152 of 219

TM 9-2350-274-BD

COMMUNICATIONS SYSTEM

11-6.

OBSERVABLE SYMPTOM:

THE INTERCOM DOES NOT WORK ON ANY

CONTROL BOX

Detailed Assessment Steps:

■

1. Check that the DC power is available to the turret by checking the dome light or other electrical

equipment in the turret.

■

2. Check that the MX-7777 or MX-7778 Transient Voltage Suppressors operational by

depressing the Battle-Override switch. If the suppressor is bad, replace or repair as

necessary.

3.

Check that communication equipment is turned on and the switches are in the

proper positions. (Refer to para. 11-4.)

4.

Check that cables are connected to the proper connectors, correctly aligned, and

tightly connected to the receptacles.

5.

Jiggle the cables to check for intermittent opens or shorts.

a.

If a defective cable is found, follow the procedures listed below:

(1) Replace the defective cable in accordance with standard repair

procedures.

(2) Replace the defective cable with an acceptable replacement cable

(refer to para. 11-16).

(3) Repair the defective cable in accordance with the repair procedures

in para. 11-12, or the electrical chapter of TM 9-2350-276-BD.

b. If a defective cable is not found, then follow the troubleshooting

procedures in TM 11-5820-401-12.

11-7.

OBSERVABLE SYMPTOM:

THE INTERCOM WORKS ON SOME CONTROL

BOXES BUT NOT ALL

Detailed Assessment Steps

1.

Repeat steps 3 thru 5 in para. 11-6.

2.

Replace CVC helmet and connecting cable with a known operational CVC helmet

and connecting cable.

a.

If the problem no longer exists, no further action is necessary.

b.

If the problem has not been corrected, go to step 3.

11-6

Change 3