Overvoltage; Fluctuating Voltage - Kohler TP-5353 Service Manual

Overvoltage

If overvoltage occurs, disconnect harness plug at AVR
(voltage regulator). If overvoltage continues, the
problem lies in the photo transistor circuit and/or SCR
assembly; proceed through the following checks. If
output voltage disappears, the problem is in the AVR
(voltage regulator), including connections and/or wiring.
1. Examine photo transistor board for visible signs of
damage (open foil pattern or heat discoloration).
Replace photo transistor board if visibly damaged.
If overvoltage continues after replacement of photo
transistor board, proceed to Step 2.
2. Remove green (center) lead from G terminal and
red lead from F+ terminal of SCR assembly. (Tape
each terminal end of leads to prevent contact with
adjacent metal components.)
3. With safeguard breaker open, start generator set.
The lack of AC output indicates the SCR assembly
is functioning properly. If overvoltage continues,
replace the SCR assembly.
When replacing SCR assembly, do not exceed
torque value of 8 in. lbs. (0.9 Nm) when tightening
SCR mounting bolts.
7-6 Generator Troubleshooting
NOTE
NOTE
4. If overvoltage is read with the safeguard breaker
closed, check for an open circuit in leads V7 and V8
to the AVR (voltage regulator ). If these circuits are
open or shorted, repair or replace. Check the
voltage rheostat circuit (leads 67 and 68). Repair or
replace as necessary.
5. If all the circuits described in step 4 are okay, check
the voltage regulator (AVR) as described later in
this section.

Fluctuating Voltage

1. Check the generator output leads for proper
connections. Refer to Wiring Diagrams.
2. Check for loose connections to the AVR (voltage
regulator), LED board, photo transistor board, or
SCR assembly.
3. Check the stator for shorted or open windings; refer
to stator testing later in this section.
4. Verify AVR adjustment. See AVR (Voltage
Regulator) Operation and Adjustment later in this
section.
TP-5353 8/94