TC- 446 Service Manual
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29
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TC500 Series Troubleshooting Chart
I. Receiver:
1. No receive or low RX sensitivity / intermittent RX output:
N
Y
N
-
Y
N
Y
N
Y
N
N
Adjust TC3, TC4, TC5; Check
TC3, TC4, TC5, C94, C93,
C106, C163, C164, C105;
Replace faulty components.
Start
Inject
21.4MHz
signal into Q22 pin
C; SSG output
≤
-92dbm; Audio heard
from SPK?
Inject 21.4MHz
signal into XF1 IN;
SSG output
≤
-103dbm ; Audio
heard from SPK?
Check
CF1(455K2nd IF
filter), IC1(IF IC),
X1(20.945M 2
nd
LO),
CD1(demodulator);
Check XF1 (1
st
IF filter), Q22;
Replace faulty
components.
Inject 1KHz RX
signal into
Q27(RF AMP)IN;
SSG
≤
-113dbm;
Audio heard from
SPK?
Power
supply at
Q9(5R) OK?
Check Q23
(mixer),
Q27, Tc5;
Replace
faulty
Check if
no-solder joint
at IC11 pin
23; Check
Q9; Replace
faulty
components.
Inject 1KHz RX
signal into
antenna (wide:
SSG
≤
-118dbm,narrow:
SSG
≤
-116dbm);
Audio heard from
Содержание TC-446
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