TM 11-6625-847-45
Refer to figure 6-4 and troubleshooting chart 2-19 for
standard dc power supplies are not available, the + 20-
localizing. and isolating malfunctions. When checking
volt dc supply voltage can be obtained from the front
pulse wave forms in pulse generator module A1A1,
panel of the test set at DC VOLTAGE test points +20 and
connect the test equipment as described in paragraph 2-
ground, and the -33 volt dc supply voltage from across
10.
test points RCVR IF HI and LO on tray A1A2, connected
to the test set and energized, with the RCVR IF TEST
SELECTOR switch set to position 1. The dc voltage
2-10.
Test Set Pulse Generator Module A1A1
required by the SM-442A/GRC is supplied by a 27-volt dc
Waveform Check
power source, connected to the POWER connector on the
test. A typical power source for the set is given in
Connect Tee Connector UG-274B/U to the output of
Generator, Signal AN/URM-127. Connect one side of
and a direct current range of 100 amperes, maximum.
UG-274B/U to connector J1 on pulse generator assembly
A1A1 and the other side to the trigger input on
2-6. General Troubleshooting Information
Oscilloscope AN/USM-140(*).
Connect 20 volts dc
between terminals 3 and 4 (ground) and -30 volts dc
Information on the function and operation of test set and
between terminals 14 and 4 (ground), using the test set as
test tray controls, switches, and lamps is contained in TM
a power source (para. 2-5). Adjust the output of the
11-6625-847-12.
Instructions
for
removal
and
AN/URM-127 to 500 cycles per second (cps) at 2 volts
replacement of modules, board assemblies, and
peak to peak. Connect the AN/USM-140(*) probe as
component parts are given in paragraphs 3-1 through 3-
directed in troubleshooting chart 2-19, and compare the
54. When replacing any defective wiring or component
waveforms obtained with those illustrated in figure 1-17.
parts, refer to the wiring and soldering instructions in
notes, paragraph 3-12.
2-11. Troubleshooting Test Set If. Oscillator Modules
A1A2, A1A3, and A1A4
2-7. Troubleshooting Test Set Dc-to-Dc
Converter and Regulator Module A3
When troubleshooting any of the oscillator modules,
When troubleshooting dc-to-dc converter and regulator
perform the general support tests in paragraph 4-8. Refer
module A3, perform the general support tests given in
to figure 1-19, figure 6-3 and figure 6-6 and the
Refer to figure 1-18 and the
troubleshooting chart (para. 2-20) for localizing and
troubleshooting chart in paragraph 2-18 for localizing and
isolating malfunctions. The only difference in the circuitry
isolating malfunctions.
of the oscillator modules is the operating frequency of the
crystal used in each module. When signal tracing in any
2-8.
Troubleshooting Test Set Dc-to-Dc Converter
of the oscillator modules, use the test set as a source of
power and the AN/USM-140(*) with a probe having dc
Module A2
isolation. Make sure that one side of AN/USM-140(*) is
grounded; connect the probe as directed in the
Dc-to-dc converter module A2 is an encapsulated unit
troubleshooting chart (para. 2-20).
which is not repairable. To troubleshoot the module,
perform the general support tests given in paragraph 4-5.
2-12. Troubleshooting Test Set Mixer Module A1A5
Replace module A2 if any of the performance standards
are not satisfied.
When troubleshooting mixer module A1A1, perform the
2-9.
Troubleshooting Test Set Pulse Generator
general support tests in paragraph 4-9. Refer to figure 6-
3 and the troubleshooting chart in paragraph 2-21 for
Module A1A1
localizing a isolating malfunctions.
When troubleshooting the pulse generator module,
perform the general support tests given in paragraph 4-7.
Change 1
2-4
Previous Page
