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SERVICING THE AT10.1
56
SYMPTOM
PROBABLE
CAUSE
RECOMMENDED ACTION
DC OUTPUT
FAILURE
indicator is
on, but ac
and dc
breakers are
closed; ac
input voltage
is normal
1. Defective
rectifier bridge
2. Defective
control circuit
board A1
3. Defective
transformer T1
4. Defective dc
breaker
1. Use a clamp-on ammeter to measure the current in wire #
12 or # 11. If it is less than 70% of the dc output current, one
of the SCRs or diodes is defective. Replace the rectifier
module.
2. Turn off both front panel circuit breakers. Then turn on the
dc breaker, followed by the ac breaker. If the charger output
voltage and current are normal, but the DC OUTPUT
FAILURE indicator is still on, replace the control circuit board.
3. Use an ac voltmeter to measure the ac voltage from T1-X1
to X4. It is normally 50% to 80% higher than the rated dc
output voltage. If it is too low, check the wiring of the primary
taps. See section 1.6 for details. If it is zero, replace T1.
4. Disconnect the battery, and connect a light dc load to the
charger. Measure the dc voltage from the input terminal to the
output terminal of the circuit breaker, with the breaker on. It is
normally no more than 50 millivolts. If it is near the rated
output voltage, replace the breaker.
AC INPUT
FAILURE
indicator is on
1. AC power
failure
2. Upstream
feed
breaker/fuse is
tripped
3. Defective
wiring
4. Defective
control circuit
board A1
1. If the ac input power fails, the front panel AC ON indicator
goes out, and the AC INPUT FAILURE indicator goes on.
2. Be sure the front panel ac circuit breaker is closed. Measure
the ac voltage at TB1-L1 and L2. If it is zero, check upstream
distribution breakers and fuses.
3. Measure ac voltage at T1-H1 and T1-H5. It should be the
same as the ac supply voltage.
4. Turn off both front panel circuit breakers. Then turn on the
dc breaker, followed by the ac breaker. If the AC ON indicator
is on, but the AC INPUT FAILURE indicator is still on, replace
the control circuit board.