TM 55-4920-244-14
Table 3-2. Troubleshooting-Continued
Malfunction
Probable cause
Corrective action
2. Power source connected to
a. Lamp burned out.
tester, but power on light
b. Defective power inlet cable.
b. Replace power inlet cable.
does not indicate.
3. Switch SW-1 in T/C position;
a. Lamp burned out.
no light beam in galvano-
b. Replace power inlet cable.
b. Defective power inlet cable.
meter (GALVO-1).
4. Heater probes will not heat
a. Blown fuse (20 amp).
with switch SW-1 in T/C
b. Replace heater cable.
b. Defective heater cable.
c. Check power source and
position.
c. No input voltage.
inlet cable.
a. Lamp burned out.
5. Switch SW-1 in E.G.T. po-
b. Replace power inlet cable.
sition; no light beam in
b. Defective power inlet cable.
galvanometers (GALVO-1).
6. Heater probes will not heat
a. Blown fuse (20 amp).
b. Defective heater cable.
with switch SW-1 in E.G.T.
b. Replace heater cable.
c. Check power source and
c. No input voltage.
position.
power inlet cable.
a. Make proper connections
a. Improper connections to
7. Galvanometers (GALVO-1)
will not zero with switch
circuit being tested.
b. Replace defective instrument
b. Defective instrument cable
SW-1 in RES. position.
cable or check adapter.
or check adapter.
a. Replace defective instrument
a. Defective instrument cable
8. INSULATION CHECK
cable or check adapter.
or check adapter.
meter will not zero with
input shorted and switch
SW-1 in INSUL. position.
a. Lamp burned out.
9. Switch SW-7 in RANGE
b. Blown fuse (2 amp).
position; no light beam in
galvanometers (GALVO-2).
a. Defective tube V1.
10. Galvanometers (GALVO-2)
will not zero with switch
SW-7 in RANGE position;
relay (RLY-1) inoperative.
a. Replace tube V1, V2, or V3
a. Defective tube V1, V2, or
11. Galvanometers (GALVO-2)
will not zero with switch
V3.
SW-7 in RANGE position;
relay (RLY-1) operating.
12. R. P. M. CHECK CIRCUIT
a. BH1766 fuse blown out.
operative, all other circuits
inoperative.
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