Troubleshooting Flow Chart For Synthesizer - Motorola HT Series Service Manual

8-16

8.10.8 Troubleshooting Flow Chart for Synthesizer

Check CR201,
U210, U211, C258,
C259 & C228
YES
5V
Is U201 Pin
NO
at pin 6 of
47AT = 13
CR201
VDC
NO
Check
L202
Is U241 Pin 19
<0.7 VDC in RX &
>4.3 VDC in TX?
YES
Is U201 Pin
18 AT 4.54
VDC?
YES
Is RF level at
U201 Pin 32
>-30 dBm?
YES
Are R231,R232,
R233,C231,C232,
& C233 OK?
YES
Replace U201
NO
Correct
Problem
YES
Check Q260,
Q261 & R260
NO
YES
U201 pin 2 at
>3V in Tx and
<0.7V in Rx
NO
NO
Replace U201
If L261, C263 & C264
NO
are OK, then see VCO
troubleshooting chart
Replace or
NO
resolder
necessary
components
Maintenance: UHF Band 1 Troubleshooting Charts
Start
Visual
check of the
Board OK?
YES
YES
+5V at U201
NO
Pin's
13 & 30?
Check 5V
Regulator
NO
Are signals
at Pin's 14 &
15 of U201?
YES
Is there a short
NO
between Pin 47 and
Pins 14 & 15 of
U201?
YES
Remove
Shorts
NO
Check U248,
3.3V at U201
L201 & L202
pins 5, 20, 34
& 36
YES
Is
Is 16.8MHz NO 16.8MHz
Signal at signal at
U201 Pin 19? U201 pin
23?
NO
YES Check FL201, C206,
C207, C208, CR203
& R204
NO
Are Waveforms
at Pins 14 & 15
triangular?
YES
Do Pins 7,8 & 9
NO
of U201 toggle
when channel is
changed?
Check programming
lines between U409
and U201 Pins 7,8 & 9
NO
Is information
from
correct?
Check uP U409
Troubleshooting
Chart
Replace U201
Replace
U201
YES
YES
µ
P U409
YES