Motorola Pro Series Elite - Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

VHF Troubleshooting Charts 3-11
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at pin 27 of
U3220?
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
C3279
VCO locked?
B
Yes
16.8 MHz check at
pin 21 U3220?
Activity on U3220
sel pin?
Check FGU
No
No
A
A
Yes
Check Q3270 bias circuitry
for faults.
Rotate Freq. Knob
Check controller.
Before replacing U3220, check 2nd VCO Q3270.
Check VCO O/P level, C3272, C3273.
Yes
No
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)