Motorola PR860 Detailed Service Manual page 73

3-22
B
B
Check FGU
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
START
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
Audio at pin 27
of U303?
No
Spray of inject 1st IF into
XTAL Filter
IF Freq: 109.65 MHz
Yes
Audio heard?
No
Check 2nd LO Control
Voltage at C308
Yes
VCO locked?
No
No
17.0 MHz
check at pin 22
U303?
Yes
A
Maintenance: Low Band Troubleshooting Charts
Yes
Check Controller
Check controller.
Before replacing U303, check 2nd VCO
A
Check Q301 bias cir-
cuitry for faults.
Rotate Freq. Knob
No
Activity on
U303 sel pin?
Yes
Q301. Check VCO O/P level, C315,
C316