5: Maintenance
5-6 PRC-BC4-MS
If the voltage is below 0.6 VDC, replace the IC. If the voltage is above
1.0 VDC, replace the transistor.
9. Using an ohmmeter (or a diode checker), measure the forward and
reverse resistance of series diode 1N5400. If the forward resistance is
less than 10 ohms and the reverse resistance is very high (mega ohms),
the diode is okay; replace the pass transistor; if not, replace the diode.
Bulk Charging
Current
Regulation
This section assumes a failure occurred during the “DC Current Check”
procedure on page 5-2 if the CHARGING LED does not light up.
1. If the DC current is okay, but the CHARGING LED is not lit, refer to
“Current Source” on page 5-5.
2. Measure the DC voltage across the 0.2 ohm current sense resistor. If it
is not 0.25 ± 0.02 VDC, refer to “Status LEDs” on page 5-8.
3. Turn off the power and measure the resistance of the 0.2 ohm resistor
R2. If it is not within 5% tolerance, replace the resistor.
4. Refer to “Current Source” on page 5-5.
Float Charge
Voltage
This section assumes a failure occurred during the “Float Charge Voltage”
procedure on page 5-6 if the float charge voltage is out of specification. The
float charge voltage should be 13.3 VDC.
1. R1 (20 k ohm) and R6 (100 k ohm) are 1% resistors that form a
voltage divider that sets the float charge voltage. Turn the PRC-BC4
off (remove the AC power cable), and measure the resistance of these
resistors to verify they are within 5% of their stated value.
2. Turn the PRC-BC4 on and verify that the float charge voltage is within
specification (13.3 VDC). If it is significantly out of specification,
refer to “Current Source” on page 5-5 (step 8).
Reset Function This section assumes a failure occurred during the “Reset Circuit Check”
procedure on page 5-3 if the DC voltage does not drop when pressing the
RESET button. Turn the PRC-BC4 on for the following checks.
1. On the IC, measure the DC voltage on pin 3. Press and hold the
RESET button and observe that the voltage drops to 0 VDC.
2. If the voltage does not drop, inspect the RESET switch and associated
wiring.
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