TM 11-6625-828-45
below), procedures are outlined for sectionalizing
equipment performance checklist (TM 11- 6625-828-12)
troubles to a major circuit and for localizing troubles to a
and proceed until a symptom of trouble appears.
c. Conditions for Tests. All checks outlined in
particular stage. Parts locations are indicated in figures
21 through 2--4. Voltage and -resistance measurements
the chart are to be conducted with the test set connected
are shown in figure 4-12. Depending on the nature of the
to a power source as described in paragraph 2-4a,
operational symptoms, one or more of the localizing
unless otherwise specified.
d. Troubleshooting Chart.
procedures will be necessary. When trouble has been
localized to a particular stage, use voltage and
resistance measurements to isolate the trouble to a
NOTE
particular part.
Perform the operations in the
b. Use of Chart. The troubleshooting chart is
checklist (TM 11-6625-828-12) before
designed to supplement the operational checks detailed
using this chart, unless trouble has
in TM 11-6625-828-12. If no operational symptoms are
already been localized.
known, begin with item 1 TM 11-6625-828-45 of the
Malfunction
Probable cause
Corrective action
1.
Indicator lamp DS101 does not
No ac power is applied to the radio
Check Power Cable Assembly CX-
light and tone generator motor
test set.
337/U. Check for input voltage.
B101 does not start when
Open fuse F101I or F102.
Replace fuse.
If fuse blows
POWER-STAND- BY switch
Indicator lamp DS101 or indicator
again, check transformers T101
8106 is pressed to the POWER
lamp socket defective.
and T102, and tone generator
position.
Transformer T101 defective.
motor B101.
2,
Tone generator motor B101 starts
Defective capacitor C101.
Replace indicator lamp DS101 or
but indicator lamp DS101 does
Tone generator motor B101 defective.
socket.
not light.
Defective electron tube V15.
Replace transformer T101.
3.
Tone generator motor B101 does
Defective potentiometer R218; R219,
Replace C101.
not start but indicator. lamp
or R212.
Replace motor.
DS101 lights.
Defective resistor R207, R208, or
Replace tube.
4.
RF meter M101 needle does not
R222.
Replace defective potentiometer.
respond to ZERO SET knob
Defective capacitor C162.
Replace defective resistor.
move- ment and cannot be
Defective switch 8103.
Replace capacitor.
aligned with meter LEVEL SET
Defective plate voltage supply to
Replace switch.
line with MOD- ULATION switch
V115.
Check capacitor C161 and resistor
S102 at the OMNI position. No
Defective power supply circuit.
R206.
Replace defective
voltage at 51- ohm cap R192.
Improper output from RF unit Z104.
component.
5.
%M meter M102 needle does
Defective meter M101.
Check electron tubes V111, V112,
not respond to ZERO SET knob
Defective electron tube V115.
V115, and V114; choke 1,121;
move- ment and cannot be
Defective potentiometer R218, R129,
transformer T102; and capacitors
aligned with meter ZERO SET
or R215.
C159A, C159B, C160, C161.
line with MOD- ULATION switch
Defective resistor R220, R222, R218,
Replace defective component.
S102 at the OMNI position.
or R214.
Check electron tubes V108, V109 and
Defective capacitor C163 or C162.
V110.
Replace if defective.
Defective switch 5108.
Check other circuit details of
Defective plate voltage supply to Vi 15.
Z104. Re- place defective parts.
Defective power supply circuit.
Replace meter.
Replace tube.
Replace defective potentiometer.
Replace defective resistor.
Replace defective capacitor.
Replace switch.
Check capacitor C161 and resistor
R206.
Replace defective
component.
Check electron tubes VIII, V112,
V118, and Vi14; choke L121;
transformer T102; and capacitors
C159A, C159B, C1IO, and
C161.
Replace
defective
component.
2-3
