Motorola GP1280 Series Service Information - Page 27
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Troubleshooting Flow Chart for VCO
5.0
Troubleshooting Flow Chart for VCO
Check R3811
No
for dry joint
or faulty
A
U3801
Pin 19 =0V
No
AUX 3 at
U3701
High?
No
Change
U3701
U3801
Pin 10
>1V?
Yes
Yes
L3831,
L3832
L3833
O/C?
No
Change
U3801
Yes
Yes
Change
U3801
Yes
TRB = 3.2V
Change L3831,
L3832
AUX 3 at
U3701
High?
Check U3701
Pin 2 for 3.2V
VCTRL
Yes
0V or
13V?
No
Check for faulty parts
or dry joints of L3812,
C3806, R3806,
R3802, & L3801
START
Yes
No LO?
A
No
No
Carrier?
No
VCO OK
Yes
Check
R3829
No
L3821,
Yes
L3822,
L3823,
O/C?
No
Change
U3801
3-5
Tx
Yes
Change
L3821,L3822,
L3823, L3825