Troubleshooting Flow Chart For Receiver (Sheet 2 - Motorola GP328 Plus Service Manual

Troubleshooting charts
B
Inject RF into J101
IF Signal at
L311?
No
RF Signal at
T301?
No
RF Signal at
C310?
No
RF Signal at
C307?
No or
weak RF
RF Signal at
C301?
No
Check harmonic filters L101 & L102 and ant.
switches CR101, CR102, L104
Trace IF signal
Yes
from L311 to
Q302. Check for
bad XTAL filter.
Yes
No
1st LO O/P
OK?
Locked?
Yes
Yes
Check filter between
C310 & T301.
Yes
Check RF amp (Q301)
Stage.
Check filter between C301
& C307; program filter to
Yes
schematic test freq and
check varactor voltages.
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
Check FGU
Check T301, T302,
CR306, R308, R309,
R310
Are varactor
voltages OK?
No
Check U404 voltage. U404
can be selected by MCU
before replacing U404.
Q302 collector
Yes
OK?
IF signal
present?
Before replacing
U301, check
U301 voltages;
No
trace IF signal
Yes
Check for 2.6
VDC
No
Yes
Is R5 present?
No
Check Q210, U201
(pin 48) voltages and
U247
Yes
Check varactor filter.
5B-31
path.
A
A