Motorola MTX series - Page 119

Maintenance: VHF Troubleshooting Charts 8-29
8.12.4 Troubleshooting Flow Chart for Receiver, for all models except those with
PCB 8486473Z04 (Sheet 2 of 2)
IF Signal at
C3200?
No
RF Signal
at T3301?
RF Signal at
R3313?
No
RF Signal at
C3306?
No
RF Signal at
C3302?
No or
Check harmonic filter L3531 & L3532,
C3532 and ant. switches D3521, D3551,
L3551, R3551, C3551, C3552, L3552
Check filter between
C3302 & C3306; program
filter to schematic test
freq and check varactor
voltages.
Inject RF into J3501
Are varactor
voltages OK?
No
Yes
Check RF amp (Q3302)
Stage.
Check filter between
C3313 & T3301.
Yes
Check T3301, T3302,
CR3301, R3321, R3322,
R3323
Yes
1st LO O/P
OK?
Locked?
Yes
Check FGU
Yes
Trace IF signal
from C3200 to
Q3200. Check for
bad XTAL filter.
No
Yes
Q3200 collec-
tor OK?
IF signal
present?
Before replacing
U3220, check
U3220 voltages;
trace IF signal
path.
Yes
Check for 2.9
VDC
Is R5 present?
Check Q3721,
U3701 (pin 48)
voltages and U247
No
No
No
Check U404 voltage and if
U404 can be selected by
MCU before replacing
U404.
Check varactor filter.
No
Yes
Yes
Yes
A
A
B
weak RF