Troubleshooting Flow Chart For Receiver (Sheet 2 - Motorola GP328 Detailed Service Manual

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?
CR3301, R3321, R3322,
Yes
Yes
Check filter between
C3313 & T3301.
Yes
Check RF amp (Q3302)
Stage.
Check filter between
Yes
C3302 & C3306; pro-
gram filter to schematic
test freq and check
varactor voltages.
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
Check FGU
Check T3301, T3302,
R3323
U3701 (pin 48) volt-
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
Check Q3721,
ages and U247
Yes
Check varactor filter.
6B-43
A
A