Service manual

Low Band Troubleshooting Charts 3-25
Is U205, pin
18 at 4.54
VDC?
Signals
at Pin 14 and
15 of U205?
Is information
from
mPU409
correct?
Is U205 Pin
47 > 12V
In receive, is
Pin1<.7VandPin2>
3 Vplus in transmit is
Pin1>3VandPin2<
.7 V?
Start
Visual
check of the
Board OK?
Correct
Problem
Check 5V
Regulator
+5V at U205
Pin’s
13 & 30?
Is 17.0 MHz
Signal at
U205 Pin 19?
Check Y201,CR211,
C236,C237,C242,
R219
Replace U205
Replace or
resolder
necessary
components
Is RF level at
U205 Pin 32
>-30 dBm?
Are loop filter parts
R224,R225,R227,R
228,R229,C256,C2
57,C259 and C260
OK?
Replace U201
If R234, R238 & C297
are OK, then see VCO
troubleshooting chart
Do Pins 7,8 & 9
of U205 toggle
when channel is
changed?
Check programming
lines between U409
and U205 Pins 7,8 & 9
Replace U205
Check uP U409
Troubleshooting
Chart
NO
YES
NO
YES
NO
NO
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
Check C247, C249,
C283, C284, C285,
C286, D210, D211,
R285, and R286
3.3V at U205
pins 5, 20, 34
&36
Check U200
and L225
Is
17.0MHz
signal at
U201 pin
23?
Replace
U205
YES
NO
NO
YES
Troubleshooting Flow Chart for Synthesizer