Troubleshooting Flow Chart For Synthesizer - Motorola GM328 Service Manual

3-6
3.0

Troubleshooting Flow Chart for Synthesizer

Check D5201,
C5202, C5203, &
C5206
YES
NO
5V
U5201 Pin 47
at pin 6 of
at = 13VDC
D5201
NO
Check
R5201
Is
U5301 Pin 19
<40 mVDC in RX &
>4.5 VDC in TX?
(at VCO section)
?
YES
Is
RF level at
U5201 Pin 32
-12 < x <-25
dBm
?
YES
Are
R5221,R5222,
R5223,C5221,
C5222,& C5223
OK?
YES
Replace
U5201
NO
Correct
Problem
Is
?
YES
Check C5381
NO
Is
U5201
YES
Pin 2 >4.5 VDC in
Tx & <40 mVDC
in Rx
?
NO
Replace
U5201
If C5227
NO
is OK, then see VCO
troubleshooting chart
Replace or
NO
resolder
necessary
components
Start
Visual
check of the
Board
OK?
YES
+5V
at U5201
NO
YES
Pins
13 & 30
?
Check 5V
R e g u l a t o r
U5211
Are
signals NO
at Pins 14 &15
of U5201
?
YES
Is
there a short
NO
between Pin 47 and
Pins 14 & 15 of
U5201
?
YES
Remove
Shorts
Troubleshooting Flow Chart for Synthesizer
5V
NO
Check 5V
at U5201
Regulator
pins 5, 20, 34
U5211
& 36
YES
Is
Is
16.8MHz
16.8MHz NO
signal at
Signal at U5201
U5201 Pin
Pin 19
23?
?
YES
Check
Y5261 / Y5262 and
associated parts
Are
Waveforms
NO
at Pins 14 & 15
triangular
?
YES
NO
of U5201 toggle
when channel is
Check programming
lines between
U0101 and U5201
Pins 7,8 & 9
NO
from µP U0101
Check µP U0101
Troubleshooting
Chart
Replace
U5201
YES
NO
Do
Pins 7,8 & 9
changed?
YES
Is
information
correct
?
YES
Replace
U5201