5: Maintenance
PRC-BC4-MS 5-9
measure the resistance across the bias diodes and series 10 k ohm
resistor.
4. If the READY LED does not light up properly, proceed to step 3 in the
following procedure (CHARGE LED Failure).
5. If the FAULT LED lights up at the same time as other LEDs, replace
the transistor on the Display board and go back to step 3.
CHARGE LED Failure:
1. If the CHARGING LED does not light up properly, measure the op
amp output voltage during the bulk charge or overcharge states. If it is
not 15 VDC or more, measure the voltage on the op amp inverting pin.
If it is not at 0 VDC, replace the IC.
2. Measure the voltage across the transistor on the Display board; it
should be near ground potential if it is conducting. If it is always
conducting, the CHARGING and READY LEDs never light up. If this
is the case check the associated wiring.
3. On the Display board, measure the DC voltage at the 12 VDC
regulator (U1) output pin (pin 3). If it is not 12 ±1.5 VDC, turn off the
input power (AC or DC) and measure the resistance to ground at
output of the regulator chip. If the output is not shorted, replace the
regulator chip.
4. During the float charge state, measure the op amp output voltage. If it
is not 2 VDC or less, measure the voltage on the inverting pin (pin 6).
It should be greater than 1.5 VDC; if it is not, replace the charger IC.
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