Motorola GP series Service Manual

3-4 TROUBLESHOOTING CHARTS
4.0 Troubleshooting Flow Chart for Synthesizer
Is
16.8MHz
signal at
U201 pin
23?
5V
at pin 6 of
D201
Is
information
from µ
P U409
correct
?
Is
U201 Pin18
AT 4.6
VDC?
Is
U201
Pin47 AT =
13VDC
?
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 the
waveforms
at Pin’s 14 &15 of
U201 rectangular
?
Check
L202
Remove
Shorts
Replace or
resolder
necessary
components
Is
RF level at
U201 Pin 32 as
indicated
?
Are
R226,R209,
R210,L204,C231,
C220, C225, C218,
R216 & C217
OK
?
Replace
U201
If L203, C227 & C228
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
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
Check
D201,D202,
C244, C245,
C246 & C228
Check
U248 & L202
NO
NO
YES
NO
YES
YES
Replace
U201
Is
there a short
between Pin 47 and
Pins 14 & 15 of
U201?
Replace U201
Check
FL201, C235,
C237, C236,
CR203 & R211
3.3V
at U201 pins
5, 20, 34&
36

Motorola GP series Specifications

General

Brand	Motorola
Model	GP series
Category	Radio
Language	English