Motorola Pro Series Elite - Troubleshooting Flow Chart for Synthesizer

3-20 UHF (Band 1 and Band 2) Troubleshooting Charts
5V
at pin 6
of
CR201
Is information
from μP 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,C23
2 & 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 program-
ming 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