Motorola GP series Service Manual

3-6 TROUBLESHOOTING CHARTS
6.0 Troubleshooting Flow Chart for Synthesizer
Is
16.8MHz
signal at
U201 pin
23?
5V
at pin 6 of
CR201
Is
information
from mP
U409
Is
U201 Pin18
AT 4.54
VDC?
Is U201
Pin47 AT =
13VDC
Is
U241 Pin 19
<0.7 VDC in RX &>
4.3 VDC in
TX?
Start
Visual
check of the
Board OK?
Correct
Problem
Check5V
Regulator
+5V
at U201
Pin’s
13 & 30?
Is
16.8MHz
Signal at
U201 Pin
19?
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
Remove
Shorts
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 prgramming
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
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
NO
NO
YES
NO
YES
YES
Replace
U201
Is
there a short
between Pin 47 and
Pins 14 & 15 of
U201?
NO
Replace U201
Check
FL201, C206,
C207, C208,
CR203 & R204

Motorola GP series Specifications

General

Brand	Motorola
Model	GP series
Category	Radio
Language	English