Motorola GM380 Service Information - Page 30
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3-8
4.0
Troubleshooting Flow Chart for Synthesizer
No
5V
Yes
Is U3201
at pin 6 of
D3201
= 13VDC ?
No
Check
R3201
Is U3301 Pin 19
<40 mVDC in RX &
>4.5 VDC in TX?
(at VCO section)
Yes
Check D3201,
C3202, C3203,
C3205 & C3206
Is RF level at
U3201 Pin 32
-12 < x <-25
R3221,
R3222, R3223,
C3221, C3222,
& C3224
Replace
Correct
Problem
Pin 47
Yes
Check 5V
Regulator
U3211
No
Is U3201 pin 2
>4.5 VDC in Tx &
<40 mVDC in Rx
No
Replace
U3201
If R3227, C3226 & C3227
No
are OK, then see VCO
troubleshooting chart
dBm?
Yes
Are
No
OK?
Yes
U3201
Start
Visual
No
check of the
Board OK?
Yes
Yes
+5V at
No
U3201 Pin's
13 & 30?
Yes
Check C3319
No
Is there a short
between Pin 47 and
Pins 14 & 15 of
U3201?
Remove
Shorts
Replace or resolder
necessary components
TROUBLESHOOTING CHARTS
5V at
No
Check 5V
U3201 pins 5,
Regulator
20, 34 & 36
U3211, R3211
Yes
Is
No
Is 16.8MHz
16.8MHz
Signal at
signal at
U3201 Pin
U3201 pin
19?
23?
Yes
No
Check
Y3261, Y3263 and
associated Parts
No
Are signals
at Pin's 14 &
15 of U3201?
Yes
Are Waveforms
at Pins 14 & 15
triangular?
Yes
No
Check programming
lines between U0101
and U3201 Pins 7,8 & 9
Yes
No
Check µP U0101
Troubleshooting
Chart
Yes
Replace
U3201
No
Do Pins
7,8 & 9 of
U3201 toggle
when channel is
changed?
Yes
Is information
from µP U0101
correct?
Yes
Replace
U3201