TM 9-4910-663-34
Table 2-5. TROUBLESHOOTING (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 8.
Set circuit breaker switch CB1 to OFF position. Using ohmmeter, check for continuity between arm
of DC VOLTMETER OUTPUT VOLTAGE RANGE switch S12 and terminal 11 of PC board
assembly.
Replace switch S12 if open indication is obtained.
Step 9.
Set DC VARIABLE VOLTS switch S10 to OFF position. Using ohmmeter, check for 40,200 ohm ±
1% indication between terminals 11 and 12 of PC board assembly.
Replace resistor R9 on PC board assembly if resistance indication is not as specified.
Step 10. Set circuit breaker switch CB1 to OFF position. Connect external DC voltmeter to DC VARIABLE
VOLTS OUTPUT binding posts, observing polarity. Connect a test lead from positive (red) DC
VARIABLE VOLTS OUTPUT binding post to REGULATOR B+ binding post, and connect second test
lead from negative (black) DC VARIABLE VOLTS OUTPUT binding post to REGULATOR B-
binding post. Set DC VOLTMETER OUTPUT VOLTAGE SELECT switch S11 to BAT pos. Set
circuit breaker switch CB1 to ON position and adjust DC VARIABLE VOLTS 0-32 VDC control to
provide 10 volt indication on external DC voltmeter. Then, change external DC voltmeter leads to
calibration jacks below DC VOLTMETER OUTPUT VOLTAGE meter M2, and check to see that both
meters indicate 10 volts.
If meters fail to indicate 10 volts, replace DC VOLTMETER OUTPUT VOLTAGE SELECT switch
S11.
Step 11. Set circuit breaker CB1 to OFF position. Connect external DC voltmeter to DC VARIABLE VOLTS
OUTPUT binding posts, observing polarity. Connect a test lead from positive (red) DC VARIABLE
VOLTS OUTPUT binding post to REGULATOR G+ binding post, and connect second test lead from
negative (black) DC VARIABLE VOLTS OUTPUT binding post to REGULATOR G- binding post. Set
DC VOLTMETER OUTPUT VOLTAGE SELECT switch S11 to RECT GEN position. Set circuit
breaker switch CB1 to ON position and adjust DC VARIABLE VOLTS 0-32 VDC control to provide 10
volt indication on external DC voltmeter. Then, change external DC voltmeter connections to
calibration jacks below DC VOLTMETER OUTPUT VOLTAGE meter M2, and check to see that both
2-38
