TM 11-6625-441-34
CHAPTER 3
DIRECT SUPPORT MAINTENANCE
Section 1. GENERAL
3-1. General Instructions
inspection is to locate faults without testing or
measuring the circuits. All meter readings or
Troubleshooting at direct support maintenance
other visual signs should be observed and an
for
includes a 11 the techniques
outlined
attempt made to localize the fault to a particular
organizational maintenance and any special or
item.
additional techniques required to isolate a
(2) Operational tests. Operational tests
defective part. Direct support maintenance
frequently indicate the general location of trouble.
procedures are not complete in themselves but
In many instances, the tests will help in deter-
supplement the procedures described in TM 11-
m i n i n g the exact nature of the fault. The
6625-441-12. The systematic troubleshooting
equipment self-test procedure (TM 11-6625-441-
procedure which begins with the operational and
12) is a good operational test.
sectionalization checks that can be performed at
(3) Voltage and resistance measurements.
organizational maintenance must be completed
Follow the procedures given in paragraph 3-4 and
b y systematic troubleshooting techniques.
compare the values given in that paragraph with
the readings taken.
troubleshooting techniques.
(4) Troubleshooting charts. The trouble
symptoms listed in table 3-1 (TS-1588/AIC) and
3-2. Organization of Troubleshooting Procedures
a. General. Troubleshooting the interphone
trouble to a component part.
test set consists of localization, which means
(5) Intermittent troubles. In all these tests,
tracing the fault to a defective part responsible for
the possibility of intermittent troubles should not
the abnormal condition. Some faults, such as
be overlooked. If present, this type of trouble
burned-out resistors and shorted wires, can often
often may be made to appear by tapping or
be located by sight and smell, The majority of
jarring the equipment. Check the wiring and
faults, however, must be localized by checking
connections to the components of the interphone
voltages and resistance.
test set.
b. Localization, The tests listed below will aid
3-3. Tools and Test Equipment Required
in isolating the trouble. First, localize the trouble
to a single circuit, and then isolate the trouble
Took Kit, Electronic Equipment TK-105/G and
within that circuit by voltage, resistance, and
Multimeter TS-352 (*)/U(multimeter) are the
continuity measurements.
only items of tool and test equipment required to
troubleshoot and repair tbe interphone test set.
(1) Visual inspection. The purpose of visual
Section Il. TROUBLESHOOTING
3-4. Voltage and Resistance Measurements
b. Resistance Measurements.
CAUTION
DO NOT apply power to the interphone
a. Preparation.
t e s t s e t w h e n making resistance
(1) Remove the cover from the interphone
measurements.
test set case by sliding the cover off the hinge
pins.
(1) Connect the multimeter test probes to
(2) Loosen the captive screws across the top
-+28V and the GND binding posts on the in-
and bottom of the front panel and remove the
terphone test set front panel. The multimeter
interphone test set chassis from the case.
should indicate approximately 700 ohms. If the
3-1
