Section II. TOOLS AND EQUIPMENT
The following chart lists the test equipment and tools required for direct support maintenance.
Test equipment and tools
Associated technical manual
Electronic Counter AN/USM-459
TM 11-6625-1703-15 or TM 11-6625-2658-14
Telephone Set TA-312/PT
Test Set TS-2/TG
Test Set AN/USM-181
Tool Kit, Electronic Equipment TK-105/G
Section III. TROUBLESHOOTING
quence in which they are given. The tests are to be
performed with the TH-22/TG chassis removed from
Trouble in the TH-22/TG is isolated in three stages.
its case. Each test provided an indication that will be
The procedure starts by making operational tests on
obtained when the circuit is operating normally. So
the unit to identify the malfunction, which is then
long as the normal indications are obtained, continue
referred to under a symptom in the troubleshooting
with the operational tests. Upon completion of a test,
chart. The troubleshooting chart lists probable trou-
disconnect the test equipment used before continu-
bles that can cause the noted symptom. Probable
ing with the next test. When a normal indication is
troubles are eliminated, and the trouble causing the
not obtained for one of the tests, locate the symptom
symptom is identified by utilizing additional data
that describes the failure in the troubleshooting
supplied. The additional data comprise voltage and
chart (para 3-7b). Investigate the probable causes
associated with the noted system and take the cor-
and the wiring diagram. Reference may also be made
rective action for the cause suggested in the chart.
to the circuit descriptions in chapter 2. If the trouble
Upon completion of the corrective action, make sure
is isolated to a chassis mounted part, repairs are
that the trouble has been corrected by repeating the
authorized at the direct support category. If the trou-
operational test and noting that a normal indication
ble is isolated to a printed card or to a part mounted
is now obtained.
on a printed card, the card must be replaced. A nota-
tion should then be made stating the defect for which
a. Power Supply Output Voltage Test.
the card was replaced; this notation should accom-
(1) Operate the TH-22/TG front panel controls
pany the card when it is forwarded to a higher main-
tenance category for repair. After completion of re-
pairs, the operational tests must be repeated. If any
A control for which no position is specified
adjustments are required as a result of the repair or
may be left in any position.
to correct a trouble, refer to the applicable adjust-
ON-OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. OFF
115V AC-230V AC-26 DC
Position corresponding to power
source being used.
(2) Connect TH-22/TG to a power source. (Use
connector P1 for ac power, connector J5 for dc
quency on send card 1A1 is not authorized
for direct support maintenance. When ad-
(3) Operate the ON-OFF switch to ON.
justment is required, replace send card
(4) Use the AN/PSM-45 (set measure 18 volts
1A1 with an adjusted card, and forward
dc) to measure the voltage between ground and test
the card requiring adjustment to higher
maintenance category with appropriate
+18 volts dc 1.8.
(5) Repeat (1) through (4) above for the other two
power inputs with which the TH-22/TG can be used.
Perform the following operational tests in the se-