Troubleshooting Flow Chart For Receiver (Sheet 2 Of 2) - Motorola Professional Radio Service Manual

800 MHz Troubleshooting Charts
B
Inject RF into J101
IF Signal at
L353?
No
RF Signal at
pin 8 of U301?
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 from
Yes
L353 to U352.
Check for bad XTAL
Yes
1st LO O/P
OK?
Locked?
Yes
Yes
Replace filter
FL301
Yes
RF Signal at
CR300?
No or
weak RF
RF Signal at
the input of
FL300?
No
Check harmonic filter L101 &
L102 CR101, CR102, and
CR300

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

filter.
No
Check FGU
Check U301, R320,
R321, R322
Yes
Check RF amp
(Q302) Stage.
Yes
Replace
FL300.
Is the level of the
IF signal of the
Yes
output of U352 as
indicated?
Before replacing
U351, check U351
voltages; trace IF
signal path.
No
Yes
Is the biasing of
U352 OK?
No
Yes
Is R5 present?
No
Check Q210, U201
(pin 48) voltages
and U247
3-29
A
Replace
U352.