Motorola GP series, Detailed Service Manual

Page: 458 / 494

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