Motorola GP series Detailed Service Manual

2-4 TROUBLESHOOTING CHARTS
4.0 Troubleshooting Flow Chart for Receiver (Models with PCB
8486686Z02) (Sheet 2 of 2)
IF Signal at
L311?
No
RF Signal
at T301?
RF Signal
at C310?
No
RF Signal
at C307?
No
RF Signal
at C301?
No or
Check harmonic filters L101 & L102 and
ant. switches CR101, CR102, L104
Check filter between
C301 & C307; program
filter to schematic test
freq and check varactor
voltages.
Inject RF into J101
Are varactor
voltages OK?
No
Yes
Check RF amp (Q301)
Stage.
Check filter between
C310 & T301.
Yes
Check T301, T302,
CR306, R308, R309
Yes
1st LO O/P
OK?
Locked?
Yes
Check FGU
Yes
Trace IF signal
from L311 to
Q302. Check for
bad XTAL filter.
No
Yes
Q302 collec-
tor OK?
IF signal
present?
Before replacing
U301, check
U301 voltages;
trace IF signal
path.
Yes
Check for 3.0
VDC
Is R5
present?
Check Q210, U201
(pin 48) voltages and
U247
No
No
No
Check U404 voltage.
U404 can be selected by
MCU before replacing
U404.
Check varactor filter.
No
Yes
Yes
Yes
A
A
B
weak RF

Motorola GP series Specifications

General

Brand	Motorola
Model	GP series
Category	Radio
Language	English