Table 2-6. Troubleshooting of Laser Power Supply Control C-9135/VVG-1 (A771) - Continued
58. Using multimeter. Measure voltage
unit A79 does not display
at pins 14 and 15 of A7TA4 card
If voltmeter indicates15.0. ±1.0 V and
+5.0 ± 0.5V respectively, replace
A77A4 card and continue. with step 27
If voltmeter does not indicate +15.0 ±
1.0 V and +5.0± 0.5 V, respectively
continue with step 59).
59. Perform steps 21 thru 29.
60 Using oscilloscope, measure signal at
pin 31 of A77A4 card. If signal
compares with figure 2-13, replace
A77A4 card and continue with step 27.
If signal does not compare with figure
2-13, continue with step 13.
61. Replace gasket and unit cover
assembly (para 3-5a).
62. Remove units from hot mock-up .
63. Purge unit (TM 9-2350-230-12).
RANGE (METERS) indicator
Low voltage power supply circuit.
1. Install failed units into hot mock-
A79 is incorrect. MALF
card assembly A77A2, reply
indicator (unit A79) lights
gating circuit card assembly
WHEN range switch (unit
A77A4, counters circuit card
A75) is pressed.
assembly A77A5, interface circuit
card assembly A77A7 PFN
charge power supply A77A9 or
If malfunction occurred during actual
ranging operation, utilize R/T tester
(para 2-6) to check receiver sensitivity
and transmitter output energy. If
receiver sensitivity is not within
tolerance, perform procedure in
"Corrective action" column for item No
8. If transmitter output energy is not
within tolerance perform steps 13
thru 15 in "Corrective action" column for
Perform procedure in "Corrective
action" column for item No.2.
A "2" is displayed on the right
Counters circuit card assembly
Install failed unit into hot mock-
A7A5, Reply gating circuit card
indicator (unit A79).
Assembly A77A4, low voltage
Enable switch S1 on A77A4 card,
power supply A77A2, interface
and interlock switch S2 on, or chassis.
circuit card assembly A77A7 or
Perform portion of BIT (para 4-2a)
which will duplicate malfunction.
Disable switch S1on A77A4 card, and
interlock switch S2 on chas sis .
Remove A77A4 card para 3-5c).
Install extender card (4, table 2-1).
Insert A77A4 card into extender
Enable switch S1on A77A4 card
and interlock switch S2 on chassis.