Troubleshooting Flow Chart For Synthesizer - Motorola CDM Series Detailed Service Manual

Section 13: 3-4
3.0

Troubleshooting Flow Chart for Synthesizer

Correct
Problem
Check D5201,
C5202, C5203, &
C5206
YES
Is
NO
5 V
U5201 Pin 47
at pin 6 of
at = 13 VDC
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
6881091C63-F
NO
YES
Check C5381
NO
Is
U5201
YES
Pin 2 >4.5 VDC in
Tx & <40 mVDC
in Rx
?
NO
NO
Replace
U5201
If C5227
NO
is OK, then see VCO
troubleshooting chart
Replace or
NO
resolder
necessary
components
Troubleshooting Flow Chart for Synthesizer
Start
Visual
check of the
Board
OK?
YES
Signal at U5201
+5 V
at U5201
NO
YES
Pins
13 & 30
?
Check 5 V
R e g u l a t o r
U5211
Are
signals NO
at Pins 14 &15
of U5201
?
YES
Is
there a short
between Pin 47 and
Pins 14 & 15 of
U5201
?
YES
Remove
Shorts
5 V
NO
Check 5 V
at U5201
Regulator
pins 5, 20, 34
U5211
& 36
YES
Is
Is
16.8 MHz
16.8 MHz NO
signal at
U5201 Pin
Pin 19
23?
?
YES
NO
Check
Y5261 / Y5262 and
associated parts
Are
Waveforms
NO
at Pins 14 & 15
triangular
?
YES
Do
Pins 7,8 & 9
NO
of U5201 toggle
when channel is
changed?
Check programming
YES
lines between
U0101 and U5201
Pins 7,8 & 9
Is
NO
information
from µP U0101
correct
?
Check µP U0101
Troubleshooting
Chart
Replace
U5201
Replace
U5201
YES
YES