Motorola Professional GP340 - Troubleshooting Charts; Receiver (Sheet 1 of 2)

Chapter 3
TROUBLESHOOTING CHARTS
1.0 Receiver (Sheet 1 of 2)
VCO
locked?
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at
pin 27 of
U303?
Check Controller
Yes
No
Spray of inject 1st IF into
XTAL Filter
IF Freq: 109.65 MHz
Audio
heard?
B
Yes
No
Check 2nd LO Control
Voltage at C308
B
Yes
17.0 MHz
check at pin
22 U303?
Activity
on U303
sel pin?
Check FGU
No
No
A
A
Yes
Check Q301 bias
circuitry for faults.
Rotate Freq. Knob
Check controller.
Before replacing U303, check 2nd
VCO Q301. Check VCO O/P level,
C315, C316.
Yes
No