Troubleshooting Flow Chart For Synthesizer - Motorola GM328 Service Manual

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3.0

Troubleshooting Flow Chart for Synthesizer

Check D3201, C3203,
C3205, & C3206
YES
5V
NO
Is U1201 Pin 47
at pin 6 of
at = 13VDC
CR1202
NO
Check
R1218
Is U1377, Pin 2
<.1VDC in RX &
>4.5 VDC in TX? (at
VCO section)
YES
Is RF level at
U1201, Pin 32
-5 < x < 0 dBm?
YES
Are R1205, R1206,
R1208, C1212,
C1213 & C1214 OK?
YES
Replace
U1201
NO
Correct
Problem
YES
Check C3319
NO
Is U1201 pin 2>4.5 YES
VDC in Tx & <.1
VDC in Rx
NO
Replace U1201
If Q1202 Feedback Amp stage is
NO
OK, Then see VCO troubleshoot-
ing chart
Replace or
NO
resolder
necessary
components
Start
Visual
check of the
Board OK?
YES
YES
+9.3V at
NO
U1201
Pin 30?
Check 9.3V
R e g u l a t o r
U0641
NO
Are signals
at Pin's 14 &
15 of U1201?
YES
Is there a short
NO
between Pin 47 and
Pins 14 & 15 of
U1201?
YES
Remove
Shorts
Troubleshooting Flow Chart for Synthesizer
Check 5V
NO
5V at U1201
ulator U1250, L1201
pins 5, 13, 20,
& R1201
24 & 36
YES
Is 16.8MHz NO 16.8MHz
Signal at signal at
U1201 Pin 19? U1201 pin
23?
YES
Check Y1201, C1204,
C1206,C1207,
CR1201. & R1203
NO
Are Waveforms
at Pins 14 & 15
triangular?
YES
NO
Check programming
lines between U0101
and U1201 Pins 7,8 & 9
NO
from
Check uP U0101
Troubleshooting
Chart
Replace U1201
Reg-
Is
Replace
U1201
YES
NO
Do Pins 7,8 & 9
of U1201 toggle
when channel is
changed?
YES
Is information
u
P U0101
correct?
YES