Troubleshooting Flow Chart For Synthesizer - Motorola GP68 Service Manual

Troubleshooting
Troubleshooting Charts
NO
Is U201 Pin 32
AT = 13 VDC
Check C202,
C203,C204,C231,
CR201 & CR202
Is U201 Pin 1
<0.7 VDC in RX &
>4.3 VDC in TX?
YES
NO
Is U201 Pin 18
AT4.65 VDC?
YES
If line between
U201 Pin 18 &
U251 Pin 3 is OK,
then replace
U201
Replace or
resolder
necessary
components
Troubleshooting Flow Chart
for Synthesizer
5-4
NO
Correct
Problem
YES
Fix
Connection
NO
Is Connection
NO
between U201
Pin 1 & U251
Pin 5 OK?
YES
Replace U201
NO
Is RF level at
U201 Pin 20
between -10 &
+5 dBm?
YES
Are R202,R204,
NO
R205,C214,C215,
C216 & L201 OK?
YES
Start
Visual
check of the
Board OK?
YES
+5V at U201
NO
Pin's
3,12,19,22
& 23?
YES
NO
Are signals
at Pin's 9 &
10 of U201?
YES
NO
Is there a short
between Pin 32 and
Pins 9 & 10 of
U201?
YES
Remove
Shorts
If L203,C224,C226 & C227
and runners between
U201 Pin 20 & U251 Pin 23
are OK, then see VCO
troubleshooting chart
Replace U201
6881086C09-O
GP68 Portable Radios Service Manual
Check 5V
Regulator
Is 16.8MHz
Check
NO
Signal at
Y201,C205,C206,C211
U201 Pin 14?
R207 and CR203
YES
NO
Are Waveforms
at Pins 9 & 10
triangular?
YES
Do Pins 5,6 & 7
NO
of U201 toggle
when channel is
changed?
Check programming
lines between U401
YES
and U201 Pins 5,6 & 7
NO
Is information
µ
from P U401
correct?
Check uP U401
Troubleshooting
YES
Chart
Replace U201
March, 1997