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

VHF Troubleshooting Charts
B
Inject RF into J3501
IF Signal at
C3200?
No
RF Signal at
T3301?
No
RF Signal at
R3313?
No
RF Signal at
C3306?
No or
weak RF
RF Signal at
C3302?
No
Check harmonic filter L3531 & L3532,
C3532 and ant. switches D3521, D3551,
L3551, R3551, C3551, C3552, L3552
Trace IF signal
Yes
from C3200 to
Q3200. Check for
bad XTAL filter.
Yes
No
1st LO O/P
OK?
Locked?
Check T3301, T3302,
CR3301, R3321, R3322,
Yes
R3323
Yes
Check filter between
C3313 & T3301
Yes
Check RF amp (Q3302)
Stage.
Check filter between
C3302 & C3306; pro-
Yes
gram filter to schematic
test freq and check var-
actor voltages

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

Check FGU
Check Q3721,
U3701 (pin 48) volt-
ages and U247
Are varactor
voltages OK?
No
Check U404 voltage and if
U404 can be selected by
MCU before replacing U404
Q3200 collec-
Yes
tor OK?
IF signal
present?
Before replacing
U3220, check
U3220 volt-
No
ages; trace IF
signal path
Yes
Check for 2.9
VDC
No
Yes
Is R5
present?
No
Yes
Check varactor filter
3-17
A
A