Radio Shack TRC-447, Service Manual

Page: 13 / 52

— 13 —
PLL CIRCUIT
Check
the voltage of
TP4 approx. 1 to 4V
at CH1~7.
NG
WX No good
OK
Check
the voltage
reading at pin 15 of
IC301 is approx.
5 V.
NG
Defective Vcc line at R316
or D303.
OK
Check if there is RF
voltage at pin 16
of IC301.
NG
Defective xtal X301 or poor
soldering.
OK
Check the voltage Q305.
NG
Defective Q305.
Check whether
each CH frequency matches
the frequency indicated in
frequency chart.
NG
Check
whether there is a
pulse at pins 13 and 14 of IC401
when rotating the CH rotary
SW top side and
down side.
OK
NG
Check the soldering
between main and front wires
or check the channel switch.
OK
Good PLL is not defective.
OK
OK