TM 9-4910-663-34
Table 2-5. TROUBLESHOOTING
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1. DRIVE CONTROL CIRCUIT/VARIDRIVE/BLOWER MOTOR
a. AC POWER ON INDICATOR DS2 FAILS TO LIGHT WHEN CIRCUIT BREAKER SWITCH CB1 IS SET TO ON
POSITION.
Step 1. Shut off external power source, remove AC POWER ON indicator lamp DS2, and check lamp for
continuity with an ohmmeter.
Replace AC POWER ON indicator lamp DS2 if it is open.
Step 2. Disconnect lead from one side of CIRCUIT BREAKERS CB2 DRIVE CONTROL circuit breaker.
Using an ohmmeter, check for continuity across terminals of circuit breaker CB2 with circuit breaker
closed.
Replace circuit breaker CB2 of continuity is not obtained.
Step 3. Reconnect lead to circuit breaker CB2. Turn on external power source, set circuit breaker switch CB1
to the ON position, and close CIRCUIT BREAKERS CB2 DRIVE CONTROL circuit breaker. Using
an AC voltmeter, check for 230/460 volts ±10% between terminals Hi and H4 of transformer T1, and
for 115 volts ±10% between terminals X1 and X4 of transformers T1.
If voltage between terminals HI and H4 is normal but no voltage is obtained between terminals X1
and X4, replace transformer T1.
Step 4. With circuit breaker switch CB1 set to ON position, check for 230/460 volts AC between power in
terminals L1 and L2, L2, and L3, and L3 and L1 of starter MS1, using AC voltmeter.
If AC voltage between any pair of terminals is any value other than 230/460 volts, proceed to Step 5.
Step 5. Using AC voltmeter, check for 230/460 volts AC across each phase at input terminals of circuit
breaker switch CB1. Then, with circuit breaker switch CB1 set to ON position, check for 230/460
volts AC across each phase at output terminals of circuit breaker switch CB1.
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