TROUBLESHOOTING (Continued)

TM- 9-4910-663-34 Table 2-5. TROUBLESHOOTING (Continued) MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Step 4. Set circuit breaker switch CB1 to OFF position. Using ohmmeter, check for continuity across terminals of high voltage compartment door interlock switch S4 while manually operating switch. Replace switch S4 if continuity indication is not obtained. Step 5. With circuit breaker switch CB1 set to OFF position, and the high voltage compartment door open, check for continuity across terminals of START switch S3, using ohmmeter, while START switch is depressed. Replace START switch S3 if continuity indication is not obtained. Step 6. With circuit breaker switch CB1 set to OFF position, check for continuity across terminals of STOP switch S2, using ohmmeter, as switch is actuated. Open indication should be obtained with switch S2 depressed, and continuity indication should be obtained with switch S2 in normal up position. Replace STOP switch S2 if indications are not as specified. Step 7. With circuit breaker switch CB1 set to OFF position, check for 2-ohm resistance indication across actuating coil of drive starter MS1, using low resistance scale of ohmmeter. Replace coil of drive starter MS1 if open or short circuit indication is obtained. Step 8. With circuit breaker switch CB1 set to OFF position, check for zero resistance across each contact of drive starter MS1, using low resistance range of ohmmeter, while manually actuating drive starter MS1. If some resistance is noted, remove drive starter cover and clean contacts. If contacts are burned or pitted excessively, replace contacts. Step 9. Set circuit breaker switch CB1 to ON position. Press START switch S3 and check for single-phasing of varidrive, which is indicated by humming noise from varidrive motor. 2-18