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TM 55-4920-400-13
CHAPTER 3
AVIATION INTERMEDIATE MAINTENANCE INSTRUCTIONS
Section I.
SPECIAL TOOLS AND REPAIR PARTS
3-1. Special Tools. No special tools are recquired
3-2. Repair Parts. The repair parts required for
for maintenance of the tester.
the maintenance of the tester are listed in Section
VII.
Section II.
TROUBLESHOOTING
3-3. General. This section provides maintenance
3-4. Troubleshooting. A tabulation of symptoms
personnel with information useful in diagnosing
of probable troubles and remedies which are likely
and correcting failures of the tester.
to be encountered before, during, or after operation
and repair of the equipment are contained in the
table below.
Table 3-1.
Troubleshooting Chart
Item No.
Trouble
Probable Cause
Possible Remedy
1
Indicator light does not Open rectifier or shorted capacitor
Replace rectifier.
illuminate and motor
does not run when power
switch is in ON position.
2
Fuse blows when power
switch is placed in ON
position.
and motor. (Check voltage on coded
lugs of rectifier.) If voltage is
present with no dc voltage across
the lugs, either the rectifier is open
or capacitor or motor is shorted. Dis-
connect lead from the rectifier and
recheck voltage across the coded
lugs of rectifier. If dc voltage is now
present, capacitor or motor is
shorted.
Open transformer primary winding
on input leads. (Disconnect plug
mating with J1 and check resis-
tance between pins 1 and 2 at T1.
Resistance check on J1 between
pins 1 and J. (Approx. 2.8 ohms)
Open transformer, secondary wind-
ing. Check voltage across termin-
als 3 and 4 of T1, 25V (rms).
If zero voltage, disconnect a lead
from terminal 3 or 4 and recheck
voltage; if still zero, transformer
is defective.
Short in electric motor. (Check
continuity for shorts. ) AC
OPERATION ONLY’
Shorted transformer primary wind-
ings. (Check for continuity and
for shorts).
Replace capacitor.
Replace motor.
Replace motor.
Replace transformer.
Replace transformer.
Replace transformer.
Repair or replace motor.
Replace transformer.
3-1
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