TM5-1260-206-34
DAC Troubleshooting Procedures - Continued
Table 3-2.
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 3.
Check that malfunction is corrected.
If not, refer faulty DAC to depot maintenance personnel.
SONALERT SOUNDS REPEATEDLY
5.
Step 1.
Remove DAC top and bottom cover plates.
Remove all printed circuit cards.
Energize DAC
Using a multimeter, perform the following measurements.
(See FO-8.) If the normal indication disappears, the card/
assembly being inserted is shorted.
IF NORMAL INDICATION
NORMAL
PIN NO.
IS NOT OBTAINED
INDICATION
ACTION
Initially
-15V
Replace power supply.
A21
+15V
A76
Reinsert
A21
-15V
Replace card A.
+15V
card A
A76
Reinsert
A21
-15V
Replace card B.
+15V
card B
A76
Replace card C.
Reinsert
A21
-15V
+15V
card C
A76
Reinsert
A21
-15V
Replace card D.
+15V
card D
A76
Reinsert
-15V
Replace card F.
A21
+15V
card F
A76
Replace card G.
Reinsert
A21
-15V
+15V
card G
A76
Step 2.
peak-to-peak signal is present at TP3 of card A.
If good, replace card G.
Step 3.
Check for continuity of pins A28, A32, A38, A42, A58, A68,
3-5