Troubleshooting Flow Chart For Receiver (Sheet 2 Of 2) - Motorola 6864115B62-C Detailed Service Manual

3-2

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

1.1
B
Inject RF into J4401
IF
Signal at
C3101?
No
RF
Signal at
T4051?
No
RF
Signal at
C4015?
No
RF
Signal at
C4009?
No or
weak RF
RF
Signal at
C4025?
No
Check harmonic filter
L4491-L4493, C4492, J4401
and ant.switch
D4471, D4472, L4472.
Trace IF signal
Yes
from C3101 to
Q3101. Check for
bad XTAL filter.
Yes
1st
LO level OK?
Locked?
D4051, R4052, L4008.
Yes
Yes
Check filter between
C4015 & T4051.
Yes
Check RF amp (Q4003)
Stage.
Check filter between
Yes
C4025 & C4009.
Check tuning voltage
at R4060.
No
Check FGU
Check T4051, T4052,
Is
tuning voltage
OK?
No
Check U4501.
TROUBLESHOOTING CHARTS
IF
Yes
signal at Q3102
collector?
Before replacing
U3101, check
U3101 voltages.
No
Yes
Check for
5VDC
No
Yes
Is 9V3
present?
No
Check Supply Voltage
circuitry. Check Q0681,
U4211 and U0641.
Yes
Check varactor filter.
A
A