Troubleshooting Flow Chart For Synthesizer - Motorola GP340 Service Information

3-4
4.0

Troubleshooting Flow Chart for Synthesizer

Check CR201,
U210, U211,
Correct
C258, C259 &
Problem
C228
YES
NO
5V Is U201
at pin 6 of
Pin47 AT =
CR201
13VDC
NO
YES
Check
L202
Is
U241 Pin 19
<0.7 VDC in RX &>
4.3 VDC in
TX?
YES
Is
U201 Pin18
AT 4.54
VDC?
YES
Is
RF level at
U201 Pin 32
>-30 dBm?
YES
Are
R231,R232,
R233,C231,C232,
& C233
OK?
YES
Replace
U201
NO
Check Q260,
Q261 & R260
NO
U201
YES
pin 2 at
>3V in Tx and
<0.7V in
Rx
NO
NO
Replace U201
NO
If L261, C263 & C264
are OK, then see VCO
troubleshooting chart
Replace or
NO
resolder
necessary
components
Start
Visual
check of the
Board OK?
YES
YES
+5V
at U201
NO
Pin's
13 & 30?
Check5V
Regulator
Are
NO
signals at
Pin's 14 &15
of U201?
YES
Is
there a short
NO
between Pin 47 and
Pins 14 & 15 of
U201?
YES
Remove
Shorts
TROUBLESHOOTING CHARTS
3.3V at
NO
Check U248,
U201 pins 5,
L201 & L202
20, 34&
36
YES
Is
Is
16.8MHz 16.8MHz
NO
Signal at
signal at
U201 Pin
U201 pin
19?
23?
YES
Check
FL201, C206,
C207, C208,
CR203 & R204
Are
Waveforms
NO
at Pins 14 & 15
triangular?
YES
Pins 7,8 & 9
NO
of U201 toggle
when channel is
changed?
Check prgramming
lines between
U409 and U201
Pins 7,8 & 9
NO
information
from mP
Check uP U409
Troubleshooting
Chart
Replace U201
Replace
U201
YES
NO
Do
YES
Is
U409
YES