Troubleshooting Flow Chart For Receiver (Sheet 1 Of 2) - Motorola GP88s Service Manual

9A-52 Troubleshooting charts
START
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
Yes
Audio at pin
Check Controller
27 of U301?
No
Spray of inject 1st IF into
XTAL Filter
A
IF Freq: 45.1MHz
Check Q320 bias
Yes
circuitry for faults.
Audio heard?
B
Rotate Freq. Knob
No
Check 2nd LO Control
Voltage at C363
Activity
No
on U301
LVZIF_SEL
pin?
Yes
B
VCO locked?
Check controller
Yes
No
Before replacing U301, check 2nd
VCO Q320. Check VCO O/P level,
16.8 MHz
No
C351, C352.
Check FGU
check at pin
22 U301?
Yes
A

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)