Troubleshooting Flow Chart For Synthesizer - Motorola HT Series Service Manual

8-40

8.13.5 Troubleshooting Flow Chart for Synthesizer

NO
Check C247, C249,
Is U205 Pin
C283, C284, C285,
47 > 12V
C286, D210, D211,
R285, and R286
In receive, is
Pin 1 < 0.7 V and Pin 2
> 3 Vplus in transmit is
Pin 1 > 3 V and Pin 2 <
0.7 V?
YES
Is U205, pin
18 at 4.54
VDC?
YES
Is RF level at
U205 Pin 32
>-30 dBm?
YES
Are loop filter parts
R224,R225,R227,R
228,R229,C256,C2
57,C259 and C260
OK?
YES
Replace U201
NO
Correct
Problem
YES
NO
NO
Replace U205
If R234, R238 & C297
NO
are OK, then see VCO
troubleshooting chart
Replace or
NO
resolder
necessary
components
Maintenance: Low Band Troubleshooting Charts
Start
Visual
check of the
Board OK?
YES
YES
+5V at U205
NO
Pin's
13 & 30?
Check 5V
Regulator
YES
NO
Check U200
3.3V at U205
and L225
pins 5, 20, 34
& 36
YES
Is
Is 17.0 MHz 17.0MHz
NO
Signal at signal at
U205 Pin 19?
U201 pin
23?
YES
NO
Check Y201,CR211,
C236,C237,C242,
R219
NO
Signals
at Pin 14 and
15 of U205?
Do Pins 7,8 & 9
NO
of U205 toggle
when channel is
changed?
Check programming
lines between U409
and U205 Pins 7,8 & 9
NO
Is information
m
from
correct?
Check uP U409
Troubleshooting
Chart
Replace U205
Replace
U205
YES
YES
P U409
YES