Table 2-4. Troubleshooting, Local Control Unit.

TM 11-5820-477-30

NOTE

T h e information in table 2-4 applies to all models of the local control unit, exc

noted.

Table 2-4. Troubleshooting, Local Control Unit.

Malfunction

T e s t or Inspection

C o r r e c t i v e Action

1 . NO RINGER SIGNAL OUTPUT.

Step 1. Check magneto G101 for output voltage.

If output is inadequate, replace magneto (paragraph 2-9).

Step 2. Check capacitor C112.

I f defective, replace (paragraph 2-13).

3. Check audio line transformer T101 by checking winding resistance between terminals 5 and 6

Step

o f transformer (paragraph 2-5).

I f defective, replace (paragraph 2-13).

Step 4. Check for proper mechanical functioning and continuity of microswitch S103.

I f defective, replace (paragraph 2-13).

2 . BUZZER IS NOT ACTIVATED WHEN RINGER BUTTON ON REMOTE CONTROL UNIT

Step 1. Check capacitor C112.

I f defective, replace (paragraph 2-13).

Step 2. Check for proper mechanical functioning and continuity of microswitch S103.

I f defective, replace (paragraph 2-13).

3 . CALL LAMP DOES NOT LIGHT WHEN RINGER BUTTON ON REMOTE CONTROL UN

( A - , B- AND C- MODELS ONLY).

Step 1. Check for defective lamp.

I f defective, replace (paragraph 2-14).

Step 2. Check for defective call lamp control relay by checking relay windings out of the

Resistance between terminals 1 and 2 should be 5,000 ohms; resistance betwee

and 4 should be infinite.

I f defective, replace (paragraph 2-12).

2-15