Motorola GP344 Detailed Service Manual page 46

2-4
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,
Yes
Trace IF signal from
C3200 to Q3200. Check
for bad XTAL filter.
Yes
1st LO O/P OK?
Locked?
Yes
Yes
Check filter between C3313 &
T3301.
Yes
Check RF amp (Q3302) Stage.
Yes
Check filter between C3302 &
C3306; program filter to schematic
test freq and check
varactor voltages.
L3552
Figure 2-3 Troubleshooting Chart for Receiver (Sheet 2of 2)
No
Check FGU
Check T3301, T3302, CR3301,
R3321, R3322, R3323
Are varactor
voltages OK?
No
Check U404 voltage and if U404 can
be selected by MCU before replacing
U404.
TROUBLESHOOTING CHARTS
Q3200 collector
OK?
Yes
IF signal present?
Before replacing
U3220, check U3220
No
voltages; trace IF
Yes
Check for 2.9 VDC
No
Yes
Is R5 present?
No
Check Q3721, U3701 (pin 48)
voltages and U247
Yes
Check varactor filter.
signal path.
A
A