a metal part of the charger. Look for wires that are near any metal part and inspect for possible breakdown
caused by shipping The heatsink of the diodes and the transistor control unit are insulated from ground through
the mounting legs. (NOTE On units with ground detector lights or relays, the ohmmeter will read a high
resistance to ground on the DC to ground check. The bulbs can be removed for the ground check and the reset
switch can be used to disconnect the ground detector relays.)
III. CHARGER IN SERVICE BUT NOT CHARGING BATTERY:
A. Check the AC input and DC output fuses. Fuses can be checked by pulling the fuse out of the charger and
checking with an ohmmeter or measuring the voltage across the fuse with the unit operating. If no voltage is
indicated across the fuse, the fuse is good. A voltage check should also be made at the input terminals and on
the unit side of the fuse.
Measure the DC output voltage at the output terminals, the unit side of the fuse, and at the battery terminals.
The voltage should be essentially the same for all three measurements.
AC or DC fuses are blown. An AC fuse blown on 30 units could indicate a blown diode A blown DC fuse could
indicate a defective diode on 10 units. Check diodes in accordance with diode trouble shooting sheet. Shorts or
grounds indicated in II could blow AC or DC fuses Check for short in load circuit - remove outside leads
Remove battery and check DC output voltage. If there LS no output voltage, check the following:
Check secondary AC voltage by measuring the voltage on 10 center tapped units from the DC negative
terminal to the pigtail end of the one diode, then to the pigtail end of the other diode The AC reading should
be approximately nominal DC voltage Measure from pigtail end of one diode to the other, reading should be
twice the DC nominal. On 10 bridge units, measure voltage across 2 sets of pigtail ends of diodes for
voltage reading. On 30 units with forward and reverse polarity diodes, the AC reading should be taken
between diode heatsink 1 and 2, 2 and 3, and 1 and 3, for nominal reading. If there is no reading on 10
units, or very low voltage indicated on 30 units, check for broken primary wire.
Check DC voltage. On center tapped units, check voltage from negative terminal (NOTE: Inspect CT wire
from transformer to negative terminal including wire crimp beneath terminal board) to heatsink. Follow the
connecting positive lead making voltage measurements through to positive output terminal. On bridge units,
DC reading may be taken across the heatsinks. Follow connecting wires taking readings through to both
output terminals. On 30 units, two heavy DC leads connect to the jumpered ends of the pigtail ends of the
diodes. Make reading at these points up through to output terminals.
If charger has DC output voltage, (check without battery connected) but will not charge the battery, make the
following checks with AC "ON" and the battery connected.