Radio Shack TRC-447, Service Manual

Page: 15 / 52

— 15 —
TX SECTION CHECK
Check the CB/WX
switch and the
connections.
NG
Does not transmit
Defective or bad contact in
antenna connector, or defective
CB/WX switch.
NG
Check the voltage at
pin 1 of IC401.
OK
OK
Check the
voltage at pin 10 of IC401.
(PTT ON: 5 V,
PTT OFF: 0 V)
Check the
MIC and JACK.
NG
Change MIC.
OK
Check the
soldering between
Front and Main
PCBs.
NG
Resolder.
NG
See PLL
section.
OK
Check the
voltage at Pin 10 of IC301.
(PTT ON: 5V)
OK
Check the voltage at
Q402 and Q406.
OK
NG
Replace Q402 or Q406.
OK
Check the voltage
of Q501.
NG
Replace Q501.
OK
Check the
voltages of Q201, 202
and Q203.
NG
Replace Q201, 202
and/or Q203.
OK
Check the Modulation.
NG
Check the Microphone
and MIC jack.
NG
Replace Microphone or
MIC jack.
OK
Check the
voltage Q204, 205, 206,
Q207, 208, 209.
NG
Replace defective parts.
OK
Good
OK
Good
OK
NG
NG
Check whether
TX LED turns on.
See system control section.