Troubleshooting Flow Chart For Receiver (Sheet 1 - Motorola GP328 Plus Service Manual

5B-30
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 U301?
No
Spray of inject 1st IF into
XTAL Filter
IF Freq: 45.1MHz
Yes
Audio heard?
No
Check 2nd LO Control
Voltage at C363
Yes
VCO locked?
No
16.8 MHz
No
check at pin 22
U301?
Yes
A
Yes
Check Controller
Check controller.
Before replacing U301, check 2nd VCO
Troubleshooting charts
A
Check Q320 bias cir-
cuitry for faults.
Rotate Freq. Knob
No
Activity on
U301 sel pin?
Yes
Q320. Check VCO O/P level, C351,
C352.