
Maintenance:
UHF Troubleshooting Charts
3-13
5V
at pin 6 of
CR201
Is information
from
μ
P U409
correct?
Is U201 Pin 18
AT 4.54 VDC?
Is U201 Pin 47
AT = 13 VDC
Is U241 Pin 19
<0.7 VDC in RX &
>4.3 VDC in TX?
Start
Visual
check of the
Board OK?
Correct
Problem
Check 5V
Regulator
+5V at U201
Pin’s
13 & 30?
Is 16.8MHz
Signal at
U201 Pin 19?
Check FL201, C206,
C207, C208, CR203 &
R204
Are signals
at Pin’s 14 &
15 of U201?
Check
L202
Check Q260,
Q261 & R260
U201 pin 2 at
>3V in Tx and
<0.7V in Rx
Replace U201
Remove
Shorts
Is there a short
between Pin 47 and
Pins 14 & 15 of
U201?
Replace or
resolder
necessary
components
Is RF level at
U201 Pin 32
>-30 dBm?
Are R231,R232,
R233,C231,C232,
& C233 OK?
Replace U201
If L261, C263 & C264
are OK, then see VCO
troubleshooting chart
Are Waveforms
at Pins 14 & 15
triangular?
Do Pins 7,8 & 9
of U201 toggle
when channel is
changed?
Check programming
lines between U409
and U201 Pins 7,8 & 9
Replace U201
Check uP U409
Troubleshooting
Chart
NO
YES
NO
YES
NO
YES
NO
YES
NO
NO
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
Check CR201, U210,
U211, C258, C259 &
C228
3.3V at U201
pins 5, 20, 34 &
36
Check U248,
L201 & L202
Is
16.8MHz
signal at
U201 pin
23?
Replace
U201
YES
NO
NO
YES
NO
YES
Troubleshooting Flow Chart for Synthesizer
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: ......