Motorola GP540 Service Information - Page 27
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Troubleshooting Flow Chart for VCO
5.0
Troubleshooting Flow Chart for VCO
Check R245
No
for dry joint
or faulty
A
U241
Pin 19 =0V
No
AUX 4
High?
No
Change
U201
U241
Pin 10
>1V?
Yes
Yes
L253
Open
Circuit?
No
Change
U241
Yes
Yes
Change
Q261
TRB =
Yes
5V? @U241
Pin 19
Change
L253
AUX 3
High?
Check U201
Pin 2 for 3.2V
VCTRL
Yes
0V or
13V?
No
Check for faulty
parts or dry joints of
L271, L273, C370,
C386, R339 & L320
START
Yes
No LO?
A
No
No
Carrier?
No
VCO OK
Yes
Check
R260
No
L243
Yes
Open
Circuit?
No
Change
U241
3-5
Tx
Yes
Change
L243