TM 11-6625-524-14-4
CABINET REMOVAL
Should maintenance require the removal of the voltmeter's cabinet, the
following procedure should be used:
WARNING
HIGH VOLTAGE capable of causing death is used inside this equip-
ment. Use extreme caution when operating or making adjustments in-
side the equipment.
(1) Disconnect the voltmeter from the AC power line before removing the cabinet.
(2) Removal: Remove the six (6) phillip's panhead screws from the cabinet's
l o w e r sides (3 per side) and lift the cabinet straight up to clear the voltmeter.
Remove the cabinet's bottom cover plate by taking out the six (6) phillip's pan-
head screws from the side edges (3 per side) and lifting the plate off.
(3) Shielding: When the voltmeter is to be operated out of its cabinet, adequate
shielding will be required to prevent power line and stray AC/RF fields from
r a d i a t i n g into the sensitive input circuits. To shield, place aluminum plates of
sufficient size to cover the chassis top, bottom and two (2) sides; ground all
plates to the chassis.
SECTION II. TROUBLESHOOTING
GENERAL
a. G e n e r a l . The first procedure in servicing a defective voltmeter is to
s e c t i o n a l i z e the fault. Sectionalization consists of tracing the fault to a printed
c i r c u i t board or switch. Once the defective area is located, isolation of the de-
f e c t i v e part is accomplished. Troubleshooting is performed by general support re-
pair person.
b. S e c t i o n a l i z a t i o n . Listed in (1) through (3) below is a group of tests
arranged to help locate the defect.
( 1 ) Visual inspection. W h e n the voltmeter is brought in for repair, remove .
the top cover and inspect as follows:
(a) Check to see that all connections and pc boards are properly seated.
Repair or replace any connections or leads that are broken or otherwise defective.
(b) Check all switches and controls for ease of operation.
(c) Inspect for loose or missing screws.
( 2 ) Operation tests. Operational tests frequently indicate the general location
o f trouble. In many instances, the tests will determine the exact nature of the
fault. The testing procedures in Chapter 6, paragraphs 6-3, 6-4 and 6-5 provide
o p e r a t i o n a l tests.
(3) Voltage and resistance measurements. Voltage and resistance measurements
are referred to in paragraphs 5-4 through 5-14, as applicable. Several waveforms
l o c a l i z e trouble.
c.
Servicing. To aid in servicing the voltmeter, major components and test
p o i n t s are labeled on the printed circuit boards for reference purposes. All cir-
c u i t boards and components are readily accessible; all solid-state devices in-
cluding the DC modulator are plug-in socket mounted.
Should component replacement become necessary, replace with the same type and
manufacture as factory installed. The component should be replaced in the exact
manner and position as the original, o t h e r w i s e the voltmeter's operating char-
acteristics and accuracies may be altered.
