Motorola GP344 Detailed Service Manual page 351

Introduction
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
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
Yes
filter to schematic test
freq and check varactor
voltages.
Figure 3-2 Troubleshooting Chart - Receiver (Sheet 2 of 2)
No
Check FGU
Check T301, T302,
CR306, R308, R309,
Are varactor
voltages OK?
No
Check U404 voltage.
U404 can be selected by
MCU before replacing
U404.
Q302
collector 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.
2-3
Yes
path.
A
A