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TM 11-5820-890-30-5
4-9.
OPERATIONAL CHECK. Continued
Step 5. REMOTE CONTROL TRANSFORMERS CHECK FOR AM-7239/VRC
AND AM-7239/VRC.
Action
Response
a. Set CAL:
FCTN GEN:
a. Scope reading is 300 to 625 mV p-p.
MODULATION: OFF
If not, go to chart 25.
FREQ: 40 kHz (38 to 42 kHz)
LEVEL: 500 mV p-p
(450 to 550 mV p-p)
FCTN: SINE.
Set CAL:
OFF.
Set STIMULUS: 8.
Set TEST EQPT SELECTOR: SCOPE.
Set LOAD: 3.
Set RESPONSE:
5. Read scope.
b. Disconnect cable at J7 and move it to J8.
b. Scope reading is 300 to 625 mV p-p.
Set RESPONSE: 4. Read scope.
If not, go to chart 26.
c. Set TEST EQPT INPUT: EXT.
c. No response.
d. Use EXT probe to check voltage from
d. Scope reading is 100 to 200 mV p-p,
E1A to E2A (GND). Read scope.
If not, go to chart 27.
e. Disconnect cable at J8 and move it to J7.
e. No response.
f. Use EXT probe to check voltage from
f. Scope reading is 100 to 200 mV p-p.
E2B to E1B (GND). Read scope.
If not, go to chart 28.
Step 6. INTERCOM AUDIO PATH CHECK FOR AM-7239/VRC AND AM-7239B/VRC.
Action
Response
a. Set STIMULUS:
OFF.
a. DMM reading is 21.6 k to 26.4 k ohms.
Set TEST EQPT INPUT: INT.
If DMM reading indicates an open circuit,
Disconnect cable at J4 and move it to J3.
go to chart 29. If not, the audio amplifier
Set LOAD: OFF.
(5A2) is bad.
Set RESPONSE: 2.
Set TEST EQPT SELECTOR: DMM.
Set RESP SEL: S1. Read DMM.
b. Disconnect cable at J3 and move it to J2.
b. DMM reading is 21.6 k to 26.4 k ohms.
Read DMM.
If DMM reading indicates an open circuit,
go to chart 30. If not, the audio amplifier
(5A2) is bad.
4-12
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