8-36 Maintenance: Low Band Troubleshooting Charts
8.13.2 Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
Activity on U303
sel pin?
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at pin 27 of
U303?
Check Controller
Yes
No
Spray of inject 1st IF into XTAL Filter
IF Freq: 109.65 MHz
Audio heard?
B
Yes
No
Check 2nd LO Control Voltage at
C308
VCO locked?
B
Yes
17.0 MHz
check at pin 22
U303?
Check FGU
No
No
A
A
Yes
Check Q301 bias circuitry for
faults.
Rotate Freq. Knob
Check controller.
Before replacing U303, check 2nd
VCO Q301. Check VCO O/P level,
C315, C316
Yes
No
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