INSTRUCTION / TROUBLESHOOTING MANUAL FOR MODEL A75M
PAGE 9 OF 13
A75M TROUBLESHOOTING
INSTRUCTIONS
Before troubleshooting unit, check for shipping damage. (i.e. broken wires, loose connections, etc.)
Quick-Check A75M Trouble Analysis
Problem: Blown AC input fuse.
1.
Check AC input voltage with tap setting on power transformer and control transformer. If AC input
and tap setting agree, see step #2.
2.
Check AC input current draw after replacing blown AC fuse. NOTE: If AC fuse clears as soon as
the AC contactor pulls in, go to STEP #5. On three (3) phase units, if the AC current is not
approximately equal, check the AC voltage input to the S2A-123 printed circuit board. Connector
#1, 4-5, 5-6, 6-4 should be 100 Vac. - 220 Vac. If this voltage is not there, retrace the wiring back
to the SCR/Diode modules. If voltage is there, continue to step #3.
3.
Check the AC voltage output on the S2A-123 printed circuit board, Connector #2, 4-1, 4-2, 4-3.
Voltages must be approximately equal and greater than 5 Vac. If it is not greater than 5 Vac.,
replace the S2A-123 printed circuit board.
4.
Connect charger to discharged battery, check output voltage and voltage across charger shunt bar.
If output voltage is below 2.3 Vpc., the voltage across shunt must not exceed 135mV. If it is over
135mV, adjust pots on the S2A-320 printed circuit board counterclockwise which lowers the output
until 97mV across the shunt bar is indicated.
S2A-320 POT ADJUSTMENTS
P3 LOW START RATE*
P4 MID START RATE
P6 HIGH START RATE
P8 LOW FINISH RATE
P9 MID FINISH RATE
P10 HIGH FINISH RATE
P11 START/FINISH THRESHOLD VOLTAGE
P1 HIGH VOLTAGE CLAMP
Verify the jumper selection on the AC input terminal
block. If Low Start Rating is 101A and 250A/`100mV
shunt is used, Adjust P3 until 101A 100mV/250A =
40.4mV across the shunt bar is indicated.
5.
If AC input fuse clears when the AC contactor pulls in make sure the correct AC fuses are being
used, time delay fuses. If the correct AC fuses are being used, disconnect P1 connector from the
FC6 printed circuit board.
6.
Replace blown AC fuse, turn on AC power. (If fuse is good, defective S2A-320 or FC6 p.c. board.)
If fuse still clears, problem is a shorted SCR/Diode module or power transformer.
7.
Separate secondary leads from P.T. to SCR/Diode modules. If fuse still clears, problem is in the
(P.T.) power transformer. If fuse is good, problem could be in the SCR/Diode module.
SEE SCR/DIODE TROUBLESHOOTING GUIDE.
