TROUBLESHOOTING (Continued)

TM 9-4910-663-34 Table 2-5. TROUBLESHOOTING (Continued) MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Replace DC VOLTMETER OUTPUT VOLTAGE RANGE switch S12 if open indication is obtained; replace DC VOLTMETER OUTPUT VOLTAGE meter M2 if continuity indication is obtained. Step 4. Connect external DC voltmeter to calibration jacks beneath DC VOLTMETER OUTPUT VOLTAGE meter M2. With all other control settings as in step 1, set DC VOLTMETER OUTPUT VOLTAGE RANGE switch S12 to X2 position, and adjust DC VARIABLE VOLTS 0-32 VDC control for 10 volt indication on external DC voltmeter. Check to see that DC VOLTMETER OUTPUT VOLTAGE meter M2 also indicates 10 volts. If DC VOLTMETER OUTPUT VOLTAGE meter M2 fails to indicate 10 volts, proceed to step 5; if meter indication is normal, proceed to step 7. Step 5. Set circuit breaker switch CB1 to OFF position. Using ohmmeter, check for continuity from arm of DC VOLTMETE OUTPUT VOLTAGE RANGE switch S12 and terminal 6 of PC board assembly. If open indication is obtained, replace DC VOLTMETER OUTPUT VOLTAGE RANGE switch S12. Step 6. Set DC VARIABLE VOLTS switch S10 to OFF position. Using ohmmeter, check for 10,000 ohm ±1% indication between terminals 12 and 6 of PC board assembly. If resistance indication is not as specified, replace resistor R8 on PC board assembly. Step 7. With all other control settings as in step 1 and external DC voltmeter connected to calibration jacks below DC VOLTMETER OUTPUT VOLTS meter M2, set DC VOLTMETER OUTPUT VOLTAGE RANGE switch S12 to X5 position. Adjust DC VARIABLE VOLTS 0-32 VDC control for 20 volt indication on external DC voltmeter. Check to see that DC VOLTMETER OUTPUT VOLTAGE meter M2 also indicates 20 volts. If DC VOLTMETER OUTPUT VOLTAGE meter M2 does not indicate 20 volts, proceed to step 8; if indication is normal, proceed to step 10. 2-37