Troubleshooting Flow Chart For Vco - Motorola Professional Radio Service Manual

3-14
No
Check R245 for dry
joint or faulty

Troubleshooting Flow Chart for VCO

Change
U241
No
Yes
Change
L253 O/C?
L253
Yes
Yes
Pin 10
TRB = 5V?
>1V?
A
Yes
Pin 19
=0V
Check for faulty parts or dry
No
joints of L271, L273, C370,
C386, R339 & L320
AUX 4
High?
No
Yes
Change
Q261
No
No
AUX 3
High?
No
Check U201
Pin 2 for 3.2V
V ctrl 0V
Yes
or 13V?
No
Change
U201
UHF Troubleshooting Charts
START
No LO?
No
Tx Carrier?
Yes
VCO OK
Check
R260
Change
L243
Yes
L243 Open
Circuit?
No
Yes
A
Change
U241