Troubleshooting Charts
9B-53
5V
at pin 6 of
D3701
Is information
from
µ
P U409
correct?
Is U3701
Pin 18 at
4.54 VDC?
Is U3701 Pin 47
13 VDC
Is U3701 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 U3701
Pin’s
13 & 30?
Is 16.8MHz
Signal at
U3701 Pin 19?
Check Y3761, C3761,
C3762, C3763, D3761
& R3761
Are signals
at Pin’s 14 &
15 of U3701?
Check
L3701,
R3701
Check R3829
U3701 pin 2 at
>3V in Tx and
<0.7V in Rx
Remove
Shorts
Is there a short
between Pin 47 and
Pins 14 & 15 of
U3701?
Replace or
resolder
necessary
components
Is RF level at
U3701 Pin 32
>-30 dBm?
Are C3721,
C3722,C3724,
R3721, R3722,
R3723 OK?
Replace U3701
If R3727, C3726 & C3727
are OK, then see VCO
troubleshooting chart
Are Waveforms
at Pins 14 & 15
triangular?
Do Pins 7,8 & 9
of U3701 toggle
when channel is
changed?
Check programming
lines between U409
and U3701 Pins 7,8 & 9
Replace U3701
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 D3701, D3702,
U3701, C3701 -
C3707
3.3V at U3701
pins 5, 20, 34 &
36
Check U3201,
L3731
Is
16.8MHz
signal at
U3701 pin
23?
Replace
U3701
YES
NO
NO
YES
NO
YES
Troubleshooting Flow Chart for Synthesizer
Replace U3701
Summary of Contents for GP88s
Page 1: ...November 2003 GP88s Portable Radio Service Manual 6804111J47 D ...
Page 4: ...iv Document History THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 16: ...xvi 4 0 Parts List for Speaker Mic Assembly 0104008J99 10 2 Glossary of Terms G 1 ...
Page 28: ...3 6 Programming Test Cable THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 52: ...5 6 Test Mode THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 56: ...6 4 Cloning Information THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 60: ...7 4 Controller Board THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 180: ...9B 48 Circuit Board Schematic Diagrams and Parts List THIS PAGE INTENTIONALLY LEFT BLANK ...