Motorola GP Series Service Manual page 282

3-2
2.0 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
B
Inject RF into J101
IF
Signal
at L353
?
No
RF
Signal at
pin8U301
?
No
RF
Signal
at C317
?
No or
weak
RF
Are
the AGC
voltages without
RF as indi-
cated
?
No
Check U302,
U350 and
CR301.
Trace IF signal
Yes
from L353 to
U352. Check for
bad XTAL filter.
Yes
1st LO O/P
OK?
Locked?
Yes
Yes
Replace filter
FL301.
Yes
Yes
RF
Signal
at C301
?
No or
weak
RF
RF
Signal at
the input
of FL300
?
Check harmonic filters
L101 & L102
CR101, CR102
and CR300
No
Check FGU
Check U301, R320,
R321, R322
Check RF amp
(Q301) Stage.
Replace
U352
TROUBLESHOOTING CHARTS
Is
the level of
the IF signal of the
Yes
output of U352 as
indicated
?
Before replacing
U351, check
No
U351 voltages;
trace IF signal
Is
Yes
the biasing
of U352 OK
?
No
Is R5
Yes
present
?
No
Check Q210, U201
(pin 48) voltages
and U247
path.
A
Replace
U352