TROUBLESHOOTING (Continued)

TM 9-4910-663-34 Table 2-5. TROUBLESHOOTING (Continued) MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION T5 to provide 5 volt indication on DC VOLTMETER OUTPUT VOLTAGE meter M2. Check to see that external DC voltmeter and AC VOLTMETER OUTPUT VOLTAGE meter M6 both indicate approximately 5 volts. If indication on external DC voltmeter is normal but AC VOLTMETER OUTPUT VOLTAGE meter M6 indicates zero, replace meter M6. Step 2. Set AC VOLTMETER OUTPUT VOLTAGE RANGE switch S27 to X2 position, and check that AC VOLTMETER OUTPUT VOLTAGE meter M6 indicates approximately 5 volts. If meter indication is not normal, proceed to step 3; if meter indication is normal, proceed to step 5. Step 3. Set circuit breaker CB1 to OFF position. Set AC VOLTMETER OUTPUT VOLTAGE RANGE switch S27 to X1 position. Using ohmmeter, check for 24,900 ohm ±1% indication between terminals 3 and 4 of PC board assembly. If resistance indication is incorrect, replace resistor R25 on PC board assembly. Step 4. With circuit breaker CB1 set to OFF position, perform continuity check of AC VOLTMETER OUTPUT VOLTAGE RANGE switch S27, AC VOLTMETER OUTPUT VOLTAGE SELECT switch S28, and associated circuits. (See FO-1.) Replace switches if defective. Repair wiring defects. Step 5. Set all controls to preliminary positions listed in table 2-2. Set AC VOLTMETER OUTPUT VOLTAGE RANGE switch S27 to X1 position. Set DC VOLTMETER OUTPUT VOLTAGE SELECT switch S11 to VAR position, and DC VOLTMETER OUTPUT VOLTAGE RANGE switch to X1 position. Leave external DC voltmeter connected as in step 1. Set AC VOLTMETER OUTPUT VOLTAGE SELECT switch S28 to CIRCUIT T1-T3 position. Connect test lead from positive DC VARIABLE VOLTS OUTPUT binding post to ALTERNATOR T1 binding post, and connect another test post to ALTERNATOR T3 binding post. Make certain that DC VARIABLE POWER SUPPLY 2-51