Chapter 3 Troubleshooting Charts; Receiver (Sheet 1 Of 2) - Motorola Professional GP340 Service Manual

1.0

Receiver (Sheet 1 of 2)

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