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Page Title:
Section II. TOOLS AND TEST EQUIPMENT |
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  TM 11-6625-524-14-2
Section II. TOOLS AND TEST EQUIPMENT
b. T e s t
Equipment.
The
test
equipment
Troubleshooting
required for troubleshooting is listed below:
a. Tools. No special tools are required.
Test equipment
Technical manual
Common name
Electronic Voltmeter ME-30(*)/U
TM 11-5511
Vtvm
Oscilloscope AN/USM-281
TM 11-6625-1703-15
Scope
AC Meter, Millivac Model MV-45A
Ac meter
Signal Generator AN/GRM-50
TM 11-6625-573-15
Signal Generator
NOTE. (*) indicates all models.
6-3. Troubelshooting Chart
to localize the trouble to a pc board or component.
(In chart below, V & R stands for voltage and
The following chart is supplied as an aid in
resistance.) Use the parts location illustrations
locating trouble in the voltmeter. This chart lists
the symptoms observed during normal operation
during troubleshooting.
Correction
Probable trouble
Symptom
Step
LINE lamp does not light when line
1
a. Fuse 3A3F1 is burned out.
a. Replace fuse. If new fuse blows,
switch is turned to ON.
check steps 2 and 3 below.
b. Replace lamp.
b. LINE lamp 3DS1 defective.
c. Check power cord; repair or
c. Defective power cord.
replace.
d. Check switch and replace, if
d. Line switch 3S1 defective.
necessary.
e. Check switch and replace, if
e. 1 1 5 / 2 3 0 v o l t s w i t c h 3 A 3 S 1
necessary.
defective.
f. Check transformer and replace, if
f. Transformer 3A1T1 defective.
necessary.
Make V & R checks and replace
2
F u s e 3A3F1 blows when LINE
Short circuit on power supply board.
faulty part.
switch is turned to ON,
a. Make V & R checks and replace
3
a. Defect on power supply board.
LINE lamp lights, voltmeter does
faulty part.
not indicate on all ranges.
b. Check switch at defective ranges.
b, Defective range selector switch
Repair or replace.
3S2.
c. Repair or replace.
c. Defective meter 3 M 1
a. Listen for a 94Hz hum. Replace if
4.
Meter indications abnormal on all
a. Defective modulator 3G1.
no hum.
ranges.
b. Make V & R checks, Use signal
b. Defective amplifier board 3A2.
t r a c i n g (para 6-4). Replace
defective part.
a. Replace defective resistor.
Meter normal on all ranges but one.
5.
a. Check resistor on switch 3S2 for
defective range.
b. Replace defective resistor.
b. Check calibration resistors on 3A3
board for defective range.
a. Remove and check cartridge.
Meter indication unstable or erratic.
a. Defective cartridge in R F probe.
6
Replace if necessary.
b. Repeat step 3 above.
b. Power supply 3A1 defective.
c. Repeat step 4 above.
c. Amplifier 3A2 defective.
and preamplifier circuits. Excessive
pickup will prevent making correct gain
NOTE
and waveshape measurements. If pickup
When operating the voltmeter removed
is a problem, shield the voltmeter by
from the cabinet, be careful to avoid
placing aluminum plates at the bottom.
powerline hum pickup in the dc modulator
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