Motorola CDM1250 Service Manual

Section 10: 3-4 Troubleshooting Flow Chart for Synthesizer
6881091C63-F
3.0 Troubleshooting Flow Chart for Synthesizer
5V
at pin 6 of
D5201
Is
information
from µP U0101
correct
?
Is
U5201 Pin 47
at = 13VDC
?
Is
U5301 Pin 19
<40 mVDC in RX &
>4.5 VDC in TX?
(at VCO section)
?
Start
Visual
check of the
Board
OK?
Correct
Problem
Check 5V
Regulator
U5211
+5V
at U5201
Pins
13 & 30
?
Is
16.8MHz
Signal at U5201
Pin 19
?
Check
Y5261 / Y5262 and
associated parts
Are
signals
at Pins 14 &15
of U5201
?
Check
R5201
Check C5381
Is
U5201
Pin 2 >4.5 VDC in
Tx & <40 mVDC
in Rx
?
Replace
U5201
Remove
Shorts
Is
there a short
between Pin 47 and
Pins 14 & 15 of
U5201
?
Replace or
resolder
necessary
components
Is
RF level at
U5201 Pin 32
-12 < x <-25
dBm
?
Are
R5221,R5222,
R5223,C5221,
C5222,& C5223
OK?
Replace
U5201
If C5227
is OK, then see VCO
troubleshooting chart
Are
Waveforms
at Pins 14 & 15
triangular
?
Do
Pins 7,8 & 9
of U5201 toggle
when channel is
changed?
Check programming
lines between
U0101 and U5201
Pins 7,8 & 9
Replace
U5201
Check µP U0101
Troubleshooting
Chart
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 D5201,
C5202, C5203, &
C5206
5V
at U5201
pins 5, 20, 34
& 36
Ch e c k 5 V
Regulator
U5211
Is
16.8MHz
signal at
U5201 Pin
23?
Replace
U5201
YES
NO
NO
YES
NO
YES

Motorola CDM1250 Specifications

General

Display	Alphanumeric
IP Rating	IP54
Frequency Range	VHF: 136-174 MHz, UHF: 403-470 MHz
Signaling	PL, DPL, MDC1200, Quick Call II
Operating Temperature	-22°F to +140°F (-30°C to +60°C)
Power Output	VHF: 1-25W; UHF: 1-25W