HYT TC-446, Service Manual

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TC- 446 Service Manual
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32
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Symptom 2: audio OK after power on, no RX audio output or audio distortion in RX (abnormal noise
output while holding down MONI)
Y
N
Y
Y N
N
Y N
Repair Example:
1) Symptom: Hold down MONI, MONI LED glows but no noise output (no RX audio), SPK resistance
OK; 6V measured at Q40 IN, but no 6V output while holding down MONI;
Cure: replace Q40
（
2SA1362
）
2) Symptom: Hold down MONI, 6.0V voltage at IC8 pin8 but no audio output at pin7;
Cure: replace IC8
Start
Hold down MONI;
Audio
output at
IC7 pin1?
Check if Q21
conductive; Check
operating status of
Q19, Q20; Check C44,
C150, C151, C152,
C153, C45; Replace
faulty components.
Hold down MONI;
Audio output at IC7
pin3?
5V voltage at
IC7 pin4?
5V voltage at
IC1(IF) pin4?
Check IC7, IC11,
peripheral
components;
Replace faulty
components.
Check the components
between Q9 and IC11 pin
23. Replace faulty
components.
Check the wiring
between IC1 pin4
and Q9; Check IC1, CD1 (C24
demodulation), peripheral
components; Replace
faulty components.