Motorola GP320

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