Troubleshooting Chart - TM-11-6665-245-340021

TM 11-6665-245-34

the test or inspection locates a failure. Retest to

3-3. Troubleshooting Chart

determine if the symptom (malfunction) has been

Besides the maintenance data (para. 3-2) provided

corrected.

for fault location, a troubleshooting chart, Table

3-1, is also included. The troubleshooting chart

3-4. Equipment Required for

provided is made up from typical or expected

Maintenance .

troubles. The chart is organized to present first

The tools and general test equipment required for

the symptom (malfunction) of the trouble; the test

m a i n t e n a n c e are listed in the Maintenance

or inspection which should be logically made as a

A l l o c a t i o n Chart (MAC) c o n t a i n e d i n T M

result of the symptom (malfunction); and the cor-

11-6665-245-12. There are no special tools re-

rective action required to correct the malfunction

quired for maintenance.

(symptom). The way to use this chart is not to go

through it step by step, but to look for the symp-

3-5. Operational Test

tom which closely matches the particular one you

The operational test (table 3-2) is designed as a

are trying to correct. Once the symptom has been

quick check of the equipment for the repair per-

selected, make the tests or inspections indicated.

son to use in developing symptom. If the equip-

The corrective action should be completed when

ment passes the test, you can be pretty well

Table 3-1. General Support Troubleshooting Chart

Malfunction

Corrective action

Test or inspection

Meter scale does not change when

Inspect selector switch know to be sure

its firmly held on to the selector

selector switch is moved through its

switch shaft.

positions.

Tighten loose setscrews on linkage

b. Remove radiacmeter panel and ex-

or knob.

amine linkage from meter to selector

switch while moving the selector

switch through its positions.

Probe may possibly be contaminated

Decontaminate probe.

2. Meter needle reads upscale when no

radioactive source is near probe win-

with radioactive materials. Use a

known good AN/PDR-56F and check

dew.

for contamination.

b. Inspect for probe window light barrier

b. Change light barrier.

puncture by passing light over the

probe window area. Use just enough

light to produce meter indication.

Connect earphones and listen for clicks

Replace faulty cord.

3. No meter readings on any range when

check source is placed across probe

on all ranges. If clicks are not heard,

window area.

suspect a faulty coil cord, and try to

work the cord into different posi-

tions with both hands while wat-

ching for a normal meter reading.

b. If clicks are heard on the earphones

b. Replace faulty meter.

without a meter indication, suspect

either a faulty meter switch, faulty

meter, or wiring problems.

4. No meter readings on one range when

Examine switch S1 front and back

Replace or repair faulty meter wafer.

the check source is placed across

wafers. Look for bent or loose con-

probe window area. Other ranges in-

tacts. Check for signal path through

dicate normally.

switch in the bad range using con-

tinuity function of multimeter.

5. No audio output at headphones on any

Check continuity from center electrode

Replace U1 or P1.

range when check source is applied

of phones jack to pin 11 of U1. If con-

to probe window. Meter readings are

tinuous, suspect faulty U1. If open,

normal.

suspect faulty connector P1 on circuit

board.

6. No meter readings or audio is heard on

Check low voltage supply readings. If

Replace faulty diode.

any ranges.

either voltage is missing or half value,

suspect open diodes CR9 thru CR12.

Check each diode for proper front to back

resistance ratio.

3-5

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