Overvoltage; Fluctuating Voltage; Led Circuit Board Test - Kohler 40COZ/33CFOZ Service Manual

7.2.2

Overvoltage

Overvoltage Test Procedure
Note: If overvoltage occurs, disconnect the harness
plug at the voltage regulator. If overvoltage
continues, the problem lies in the photo transistor
circuit and/or SCR assembly; proceed through
the following troubleshooting steps. If output
voltage disappears, the problem is in the AVR,
including connections and/or wiring.
1. Remove the LED board and cover.
2. Examine the photo transistor board for visible signs
of damage (open
discoloration). Replace the photo transistor board
if it is visibly damaged. If overvoltage continues
after replacement of the photo transistor board,
proceed to step 3.
3. Remove the green (center) lead from the G
terminal and the red lead from the F+ terminal of
the SCR assembly. Tape each terminal end of
leads to prevent contact with adjacent metal
components.
4. With the safeguard breaker open, start the
generator set. The lack of AC output indicates the
SCR assembly is functioning properly.
overvoltage continues, replace the SCR assembly.
Note: When replacing the SCR assembly do not
exceed a torque value of 0.9 Nm (8 in. lbs.)
when tightening the SCR mounting bolts.
5. If overvoltage is evident with the safeguard breaker
closed, check for an open circuit in leads V7 and V8
to the AVR. If these circuits are open or shorted,
repair or replace. Check the voltage rheostat circuit
(leads 67 and 68). Repair or replace as necessary.
6. If all the circuits described in step 5 are functioning,
check the AVR as described in Section 7.5.
7.2.3

Fluctuating Voltage

Fluctuating Voltage Test Procedure
1. Check the generator output leads for proper
connections. See Section 9, Wiring Diagrams.
2. Check for loose connections to the AVR, LED
board, photo transistor board, or SCR assembly.
3. Check the stator for shorted or open windings; See
Section 7.6, Stator.
4. Verify the AVR adjustment. See Section 7.5,
Automatic Voltage Regulator Operation and
Adjustment.
62 Section 7 Component Testing and Adjustment
foil patterns or heat

7.3 LED Circuit Board Test

The following procedure provides testing information for
the LED circuit board. Certain steps require that the
generator set be running. While the generator set is not
running, disable the generator set. See the following
safety precautions.
generator set during this test.
Accidental starting.
Can cause severe injury or death.
Disconnect the battery cables before
working
Remove the negative (--) lead first
when disconnecting the battery.
Reconnect the negative (--) lead last
when reconnecting the battery.
Disabling the generator set.
cause severe injury or death.
generator set or connected equipment, disable the generator
set as follows: (1) Move the generator set master switch to the
If
OFF position. (2) Disconnect the power to the battery charger.
(3) Remove the battery cables, negative (--) lead first.
Reconnect the negative (--) lead last when reconnecting the
battery. Follow these precautions to prevent starting of the
generator set by an automatic transfer switch, remote
start/stop switch, or engine start command from a remote
computer.
Hazardous voltage.
Can cause severe injury or death.
Operate the generator set only when
all guards and electrical enclosures
are in place.
Disconnecting the electrical load. Hazardous voltage can
cause severe injury or death. Disconnect the generator set
from the load by opening the line circuit breaker or by
disconnecting the generator set output leads from the transfer
switch and heavily taping the ends of the leads. High voltage
transferred to the load during testing may cause personal
injury and equipment damage. Do not use the safeguard
circuit breaker in place of the line circuit breaker.
safeguard circuit breaker does not disconnect the generator
set from the load.
Disconnect all load from the
WARNING
on the generator set.
Accidental starting can
Before working on the
WARNING
Moving rotor.
TP-5737 5/01
The