TROUBLESHOOTING (Continued)

TM 9-4910-663-34 Table 2-5. TROUBLESHOOTING (Continued) MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION If open circuit is indicated, replace potentiometer R36 on PC board assembly. NOTE If potentiometer R36 is replaced, tachometer must be recalibrated. 12. GENERATOR FIELD CIRCUIT a. GENERATOR FIELD CIRCUIT INOPERATIVE OR OPERATES INCORRECTLY DURING TESTS OF EXTERNAL COMPONENTS. Step 1. Set all controls to the preliminary positions listed in table 2-2. Set FIELD CIRCUIT switch S32 to MANUAL position. Set EXTERNAL FIELD EXCITER AC SYSTEM switch S31 to ON position. Set DC AMMETER FIELD CURRENT RANGE switch S30 to X6 position. Set FINE CONTROL 0-5 AMPS (MAX) switch S29 to OFF position. Set FIELD CURRENT 0-30 AMPS (MAX) control R26 and FIELD CURRENT (fine) control R27 fully clockwise. Set DC VOLTMETER OUTPUT VOLTAGE SELECT switch S11 to VAR position and DC VOLTMETER OUTPUT VOLTAGE RANGE switch S12 to X2 position. Set DC AMMETER LOAD & STARTER OUTPUT CURRENT BATTERY CHARGE CURRENT RANGE switch S14 to X1 position. Connect jumper lead between GENERATOR F and REGULATOR B+ binding posts. Connect 0-50 DC millivolt meter to calibration jacks below DC AMMETER FIELD CURRENT meter M7, observing polarity. Set circuit breaker switch CB1 to ON position. Check to see that DC VARIABLE POWER SUPPLY 0-32 VDC control T5 and VARIABLE LOAD control R32 are fully counterclockwise. Set DC VARIABLE VOLTS switch S10, MASTER LOAD DISCONNECT switch S8, and LOAD SELECTION 0-25 AMPS/0-12.5 AMPS switch S24 to ON position. Adjust DC VARIABLE POWER SUPPLY 0-32 VDC control T5 to provide a 10 volt indication on DC VOLTMETER OUTPUT VOLTAGE meter M2. Rotate VARIABLE LOAD control R32 slowly clockwise to full clockwise setting, and readjust DC VARIABLE POWER SUPPLY 0-32 VDC control T5 to maintain 10 volt indication on DC VOLTMETER OUTPUT VOLTAGE meter M2. Check to see that DC AMMETER FIELD CURRENT meter M7 and external millivolt meter both start to indicate as VARIABLE LOAD control R32 is rotated clockwise. (DC AMMETER LOAD & STARTER CURRENT BATTERY CHARGE CURRENT meter M3 should also indicate.) With 2-46