TM 11-6625-1633-45
merely a representative sample of troubles. Depending
3-5. Troubleshooting Chart
upon the nature of the operational symptoms, one or
In the troubleshooting chart below, procedures are out-
more of the localizing procedures will be necessary.
lined for sectionalizing trouble to the power supplies,
When trouble has been localized to a particular stage,
modulator, rf oscillator, or meters, and for localizing
use voltage and resistance measurements to isolate the
troubles to a stage within the various sections. The con-
trouble to a particular part.
ditions listed in the chart are not all inclusive but are
Symptom
Probable trouble
Correction
POWER indicator lamp DS1 does not
a. No ac power applied.
a. Check for input voltage.
light when POWER OFF toggle
b. Open 3 AMPS fuses F1 or F2.
b. Replace fuse. If replaced fuse
switch S8 is turned to the on posi-
blows, check for short-circuits
tion.
c. POWER indicator lamp DS1 or
c. Repair or replace the defective part.
lamp socket defective; POWER
OFF switch S8 or 115V-230V
switch S9 defective; Rfi filter
FL1 or FL2 defective.
Blower motor B1 does not operate.
a. No 115 vac power at blower motor
a. Check voltage blower motor termi-
terminals.
nals.
b. Blower motor B1 defective.
KLYSTRON indicator lamp DS2 does
a. KLYSTRON indicator lamp DS2 or
a. Repair or replace the defective part.
not light 60 seconds after POWER
lamp socket defective.
indicator lamp DS1 lights.
b. Check for 28 volts dc between test
points A4TP10 and A4TP1 (fig.
3-8); remove 60 second delay
relay K1; voltage between test
points A4TP10 and A4TP1
should be 29.5 volts dc; if no
voltage is present, check for
shorted filter capacitor C56. Re-
place defective part.
c. 60 second delay relay K1 or power
relay K2 defective.
contacts 6 and 13 of power relay
K2; connect a shorting lead
across contacts 3 and 4 and 8
and 9 of 60 second delay relay
K1; if ohmmeter indicates a
closed circuit, replace relay K1;
if ohmmeter indicates an open
circuit, replace relay K2.
d. Check for beam supply voltage of -
tive.
325 volts and adjust if neces-
sary.
e. Shorted reflector power supply.
e. Replace power supply.
Power set zero-set meter M2 does not
a. Power meter bridge supply defec-
a. Check for -108 volts dc between
indicate zero set at any position of
tive.
test points A4TP1 and A4TP3
ZERO.
SET control knob
b. Power bridge circuit defective.
ply.
Note: MODULATION selector switch
c. Power set -zero set meter M2 de-
b. Repair or replace defective parts.
S2 set at OFF position.
fective.
c. Repair or replace meter.
Power set -zero set meter M2 does not
a. Klystron filament power supply
a. Repair or replace power supply.
indicate at red reference line for any
defective.
b. Replace power supply.
position of POWER SET control
b. Beam power supply defective.
c. Repair or replace power supply.
knob.
Note: MODULATION selector switch
d. Beam current circuit or klystron
S2 set at CW position.
defective.
d. Check voltage divider capacitor
A3C1, GRID BIAS potenti-
ometer A3R11, and BEAM -
325V potentiometer A3R15
e. Loose gear on POWER SET control
defective part. Replace klystron
drive shaft.
e. Tighten loose gear and perform
align-ment procedure.
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