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Maintenance:
VHF Troubleshooting Charts
3-17
IF Signal at
L3200?
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
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 L3200 to
Q3200. Check for
bad XTAL filter.
No
Yes
Q3200
collector 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
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
Summary of Contents for PR860
Page 1: ...PR860 Two Way Portable Radio Detailed Service Manual ...
Page 2: ......
Page 5: ...iv Notes ...
Page 9: ...viii Table of Contents Notes ...
Page 13: ...Notes xii List of Figures ...
Page 17: ...1 4 Introduction Radio Model Information Notes ...
Page 51: ...2 34 Theory of Operation Voltage Control Oscillators VCO Notes ...
Page 81: ...4 4 Schematic Diagrams Overlays and Parts Lists Flex Layout Notes ...
Page 193: ...4 116 Schematic Diagrams Overlays and Parts Lists Low Band Section Notes ...
Page 196: ......