Motorola MTX series - Troubleshooting Flow Chart for Receiver, for All Models Except those with PCB 8486686 Z02 (Sheet 1 of 2)

8-20 Maintenance: UHF Band 2 Troubleshooting Charts
8.11.3 Troubleshooting Flow Chart for Receiver, for all models except those with
PCB 8486686Z02 (Sheet 1 of 2)
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at pin
27 of U301?
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
VCO locked?
B
Yes
16.8 MHz
check at pin
22 U301?
Activity on
U301 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