brilliance. If light does not come on,
Normally, R3 is set to provide R1 with
an adjustment of ±10 percent of rated
When R3 and R1 are correctly
adjusted, a small change in R1 will
turn the light bulb on and off. If light
stays either "full on", or does not
come on at all, the voltage regulator
R4 on voltage regulator affects speed
with which light turns on and off.
Normally it is factory set in the
response time to the generator. If
rotated counterclockwise, the system
voltage may oscillate (hunt). It should
then be rotated clockwise well above
the point where oscillating occurs.
The system voltage stability is very
critical at no load.
Reconnect leads to T1 primary as
they were originally connected.
Reset potentiometer R4 to its original
Disconnect test setup and reinstall
MAINTENANCE PERSONNEL SHOULD
EXERCISE EXTREME CARE WHEN
TESTING EQUIPMENT WITH POWER
On-Equipment Power Output Test. Use a
multimeter to check for the following outputs
at the F+ and F- terminals at the loads
- 12V DC at 1.1 amps
250 KW load
- 22 V DC at 1.9 amps
500 KW load
- 32V DC at 2.8 amps
Refer to figures 4-8 and 4-9 and check the
following components as indicated.
Check diodes CR8 (29), CR9 (26),
CR13 (30), CR14 (25), CR15 (33),
and CR16 (34) by disconnecting one
end of each diode and connecting an
ohmmeter (set at Rx100) across the
diode. Note reading. Reverse
ohmmeter leads to the diode and not
reading again. A good diode will read
high resistance one way and low
resistance the other way. A shorted
diode will read full scale both ways
and an open diode will read infinity
Replace shorted or open diodes.
Reconnect leads to good diodes.
Check sensing transformers T1 and
T2 (24) by applying inputs of 120
volts, 208 volts, 240 volts, 416 volts,
80 volts, and 600 volts. Check with a
multimeter for 31 volts across diodes
CR5 and CR2. Check for 31 volts
across diodes CR6 and CR3. Check
for 31 volts across diodes CR4 and
CR1. If these voltages are not
present for all inputs, the sensing
transformers may be defective and
must be replaced.
After checking transformers T1 and
T3, apply voltage to transformer
inputs and verify opening and closing
of relay K1 (23) contacts as indicated
in schematic (figure 4-9). Remove
voltage and monitor contacts for
closing and opening as indicated.
Use an ohmmeter to check for 1.0
ohms across resistor R25 (21) and
150 ohms across resistor R1 (9).
Repair by Replacement of Components. If
any of the diodes, transformers, relays, or
resistors are defective, the voltage regulator
is repairable by replacing the defective