Motorola GM328 Service Manual page 536

3-2
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
1.1
B
Inject RF into J5401
IF Signal at
C3101?
No
RF
Signal at
T5051?
No
RF
Signal at
C5015?
No
RF
Signal at
C5009?
No or
weak RF
RF
Signal at
C5025?
No
Check harmonic filter
L5491-L5493, C5492, J5401
and ant. switch
D5471, D5472, L5472.
Trace IF signal
Yes
from C3101 to
Q3101. Check for
bad XTAL filter.
Yes
No
1st LO level
OK?
Locked?
Check T5051, T5052,
D5051, R5052, L5008.
Yes
Yes
Check filter between
C5015 & T5051.
Yes
Check RF amp (Q5003)
Stage.
Check filter between
Yes
C5025 & C5009.
Check tuning voltage
at R5060.
Troubleshooting Flow Chart for Receiver
signal at Q3102
collector?
Check FGU
Check for
Check Supply Voltage
circuitry. Check Q0681,
U5211 and U0641.
Is
Yes
tuning voltage
OK?
No
Check U5501.
IF
Yes
Before replacing
U3101, check
U3101 voltages.
No
Yes
5VDC
No
Yes
Is 9V3
present?
No
Check varactor filter.
A
A