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

8-22 Maintenance: UHF Band 2 Troubleshooting Charts
8.11.5 Troubleshooting Flow Chart for Receiver, for models with PCB 8486686Z02
(Sheet 1 of 2)
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at pin 8
of U301?
Check Controller
Yes
No
Spray or inject 1st IF 44.85
MHz into
XTAL Filter
Audio heard?
B
Yes
No
Check 2nd LO signal
44.395 MHz at C367
Signal
Present?
B
Yes
Voltages
ok?
Biasing ok?
Check circuitry
around U301.
Replace U301 if
defect
No
No
A
Yes
Check Q302 bias
circuitry for faults.
Rotate Freq. Knob
Replace Q302.
Go to B
Yes
No
Check voltages on
U301
Check circuitry
around Y300.
Replace Y300 if
defect