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Page Title:
Table 4-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC-92 (cont) |
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|  TM 11-5820-873-34
Table 4-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC-92--Continued
STEP
52
Connect multimeter between 1A3A5-B and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 53
No: step 285
53
Connect multimeter between 1A1A5XA4-14 and ground.
Multimeter indicates + 10 VDC 2 VDC.
Yes: step 290
No: step 287
54
Connect oscilloscope probe to 1A1A1-E3, ground lead to
Check for noise above ambient level.
Yes: step 55
ground.
No: step 54
55
Connect oscilloscope to speaker 1A1LS1, signal input terminal,
Check for noise above ambient level.
Yes: replace speaker
ground lead to ground.
1A1LS1
No: step 56
56
Check resistor 1A1R50.
1A1R50 checks good.
Yes: step 57
No: replace resistor
1A1R50
57
Check 1A1J3.
1A1J3 checks good.
Yes: step 285
No: replace 1A1J3
58
Connect oscilloscope probe to 1A3A5-M, ground lead to
Check for noise above ambient level.
Yes: step 59
ground.
No: step 60
59
Connect oscilloscope probe to 1A1A1-E4 ground lead to
Check for noise above ambient level.
Yes: step 250
ground.
No: step 61
60
Connect oscilloscope probe to 1A3XA4J4-18, ground lead to
Check for noise above ambient level.
Yes: step287
ground.
No: step 62
Yes: step 285
61
Check resistor 1A1R51.
1A1R51 checks good.
No: replace resistor
1A1R51
62
Connect multimeter between 1A3XA4J4-12 and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 290
No: step 63
63
Connect multimeter between 1A3A5-E7 and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 287
No: step 63
64
Rotate RF GAIN control fully CCW. Connect multimeter
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 65
between 1A3XA4J4-15 and ground.
No: step 67
65
Connect multimeter between 1A3A5-E12 and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 66
No: step 287
66
Connect multimeter between 1A2M1 positive(+) pin and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: replace meter 1A2M1
No: step 69
67
Connect multimeter between 1A3A5-A and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 68
No: step 73
68
Connect multimeter between 1A3XA4J4-14 and ground.
Multimeter indicates + 12 VDC 0.8 VDC.
Yes: step 290
No: step 287
69
Connect multimeter between 1A8P2 pins 12 and 13.
Multimeter Indicates 0 V 2 VDC.
Yes: step 70
No: step 71
70
Check components 1A8K1 and 1A8CR1.
Components check good.
Yes: step 285
No: replace faulty compo-
nent.
71
Connect multimeter between 1A5XA4-11 and ground.
Multimeter indicates + 12 VDC 2 VDC.
Yes: step 292
No: step 72
72
Remove Sideband Generator CCA 1A3A3.
Multimeter indicates + 12 VDC 2 VDC.
Yes: step 294
No: reinstall Sideband
Generator CCA
1A3A3 and go to
step 285.
73
Check components 1A1R5, 1A1R54, and
Components check good.
Yes: step 285
1A1CR50.
No: replace faulty compo-
nent.
74
Connect oscilloscope probe to 1A3XA3J3-16, ground lead to
Oscilloscope displays waveform similar to Fig.
Yes: step 75
ground. Depress CW key.
4-2C.
No: step 102
75
Remove 1A8P3 from 1A7J2. Connect wattmeter to 1A7J2
Wattmeter indicates more than 90 watts.
Yes: step 76
center contact, ground lead to ground.
No: step 79
Depress CW key.
76
Reconnect 1A7J2 to 1A8P3. Remove 1A8P5 from 1A5J4.
Wattmeter indicates more than 90 watts.
Yes: step 285
Connect wattmeter to 1A5J4 center contact ground lead to
No: step 82
ground. Depress CW key.
77
Connect frequency counter to 1A3XA3J3-D,
Frequency counter indicates 1 KHz.
Yes: step 78
ground lead to ground. Depress CW key.
No: step 290
78
Connect frequency counter to 1A3XA4J4-4, ground lead to
Frequency counter indicates 1 KHz.
Yes: step 290
ground. Depress CW key.
No: step 286
4-7
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