Table 2-7. Troubleshooting of Battery Power Supply PP-6607/VVG-1 (A78) - Continued
A "1" is displayed on the right
Using a multimeter, measure voltage
at pins 6 and 20 of A78A3 card
indicator (unit A79)--continued.
If voltage difference is greater than 1.0
V, replace A78A3 card and continue
with step 25. If voltage difference is not
greater than 1.0 V, continue with step
Using oscilloscope measure signal at
pins 17 and 18 of A78A3 card. If
signals compare with figure 2-15,
continue with step 10. If signals do not
compare with figure 2-15, continue with
Using multimeter, measure voltage at
pins 2 and 12 of A78A3 card. If
multimeter indicates +15 ± 0.7 V and
+5.0 ± 0.2 V, respectively, replace
A78A3 card and continue with step 25 .
If multimeter does not indicate +15.0 ±
0.7 V and +5.0 ± 0.2 V, respectively,
return A78 unit to depot for repair.
Using multimeter. Measure voltage at
pin 14 of A78A3 card. If multimeter
indicates +5.0 ± 0.7 V, return A78 unit
to depot for repair. If multimeter
indicates +0.2 ± 0.2 V, continue with
With battery fully charged, within a
+28±:5 V range, and using multimeter
measure voltage at pin 20 of A78A3
card. The multimeter should indicate
the charged battery voltage. If
multimeter indicates within this range,
continue with step 18. If multimeter
does not indicate within this range,
continue with step 12.
Remove A78A4 card (para 3-7b).
Install extender card (14, table 2-2)
Insert AT8A4 card into extender card
Perform step 2 and continue with step
Using multimeter, meas ure voltage at
pin 8 of A78A4 card. If multimeter
indicates the same voltage as for step
10, return A78 unit to depot for repair.
If multimeter does not indicate the
same voltage as for step 10, continue
with step 17.
Using oscilloscope, measure