TM 11-6625-1696-12
5-26.
Additional Troubleshooting Information
Replacement subassemblies may become
a. Transmitter Test Facility Interlock Check.
damaged. Always replace all three subassemblies.
WARNING
(1) he transmitter test facility power
supply consists of three subassemblies: power supply
115 volts ac is present on the interlock
subassembly 406-503, power supply subassembly 455-
switch terminals. Always disconnect the
100, and voltage regulator amplifier 455-487.
test facility ac power cord before
(2) To replace the power supply, follow
working on the switches. Serious injury
the sub- assembly replacement procedures given in
or death may result from contact with
these terminals.
c. Receiver Test Facility Power Supply
The interlocks consist of two pairs of switches operated
Replacement.
by the POWER SUPPLY section hinged cover. Check
(1) The receiver test facility power supply
the interlocks as follows:
consists of two subassemblies power supply
(1) Set S1 to OFF and disconnect the ac
subassembly 457-665 and voltage regulator amplifier
power cord.
456-381.
(2) Open the hinged cover, locate the
(2) To replace the power supply, follow
interlock switches (fig. 3-1: S8, S9, S10, and S11), and
the subassembly replacement procedures given in
check to see that the are secure. Adjust and tighten as
necessary.
(3) Reconnect the ac power cord and set
5-27.
Replacement of Circuit Card Assembly No. 1
S1 to ON.
4A1A1 (fig. 5-16)
(4) Operate the interlock switches by
a. Remove RF modules test facility front
simultaneously pressing the four switch rollers. Check to
see that the +12 V and +28 V indicators light and that
panel from the case by loosening the eight captive
the fan runs.
screws, and carefully pulling the front panel directly
(5) If the conditions in (4) above are not
away from the case. Lay the front panel face downward.
b. Loosen the two captive screws in the circuit
met, higher category of maintenance is required.
(6) Release the switches and close the
card assembly No. 1 plug, and disconnect the plug.
c. Loosen the four screws that secure the
hinged cover. The + 12 V and + 28 V indicators should
light and the fan should run.
circuit card assembly to the front panel, and remove the
(7) If the +12 V and +28 V indicators do
circuit card.
not light, readjust the position of S8 and S9 and repeat
d. Aline the four captive screws of the
(6) above.
replacement circuit card assembly No. 1 with the
(8) If the + 12 V and +28 V indicators light
mounting posts and tighten the screws.
and the fan does not run, readjust the position of S10
e. Connect the circuit card assembly plug with
and S11 and repeat (6) above.
its mating connector and tighten the two captive screws.
(9) If the conditions in (6) above are still
f.
Replace the front panel in the case.
not met, higher category of maintenance is required.
b. Transmitter Test Facility Power Supply
Replacement.
CAUTION
Do not attempt to localize a power
supply fault to a subassembly by
substitution.
5-20
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