Motorola GM328

3-4 Troubleshooting Flow Chart for Synthesizer
3.0 Troubleshooting Flow Chart for Synthesizer
5V
at pin 6 of
CR1202
Is information
from uP U0101
correct?
Is U1201 Pin 47
at = 13VDC
Is U1377, Pin 2
<.1VDC in RX &
>4.5 VDC in TX? (at
VCO section)
Start
Visual
check of the
Board OK?
Correct
Problem
Check 9.3V
Regulator
U0641
+9.3V at
U1201
Pin 30?
Is 16.8MHz
Signal at
U1201 Pin 19?
Check Y1201, C1204,
C1206,C1207,
CR1201. & R1203
Are signals
at Pin’s 14 &
15 of U1201?
Check
R1218
Check C3319
Is U1201 pin 2>4.5
VDC in Tx & <.1
VDC in Rx
Replace U1201
Remove
Shorts
Is there a short
between Pin 47 and
Pins 14 & 15 of
U1201?
Replace or
resolder
necessary
components
Is RF level at
U1201, Pin 32
-5 < x < 0 dBm?
Are R1205, R1206,
R1208, C1212,
C1213 & C1214 OK?
Replace
U1201
If Q1202 Feedback Amp stage is
OK, Then see VCO troubleshoot-
ing chart
Are Waveforms
at Pins 14 & 15
triangular?
Do Pins 7,8 & 9
of U1201 toggle
when channel is
changed?
Check programming
lines between U0101
and U1201 Pins 7,8 & 9
Replace U1201
Check uP 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 D3201, C3203,
C3205, & C3206
5V at U1201
pins 5, 13, 20,
24 & 36
Check 5V Reg-
ulator U1250, L1201
& R1201
Is
16.8MHz
signal at
U1201 pin
23?
Replace
U1201
YES
NO
NO
YES
NO
YES