Chapter 3
TROUBLESHOOTING CHARTS
1.0 Troubleshooting Flow Chart for Receiver (All models except
those with PCB 8486686Z02) (Sheet 1 of 2)
16.8 MHz
at pin 22
U301?
VCO
locked?
Audio
at pin 27 of
U301?
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Check Controller
Yes
No
Spray of inject 1st IF into
XTAL Filter
IF Freq: 45.1MHz
Audio
heard?
B
Yes
No
Check 2nd LO Control Voltage at C363
B
Yes
Activity
on U301
LVZIF_SEL
pin?
Check FGU
No
No
A
A
Yes
Check Q320 bias
circuitry for faults.
Rotate Freq. Knob
Check controller
Before replacing U301, check 2nd
VCO Q320. Check VCO O/P level,
C351, C352.
Yes
No
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