Motorola 6864115B62-C Detailed Service Manual page 284

3-6
3.0 Troubleshooting Flow Chart for UHF 40W Transmitter
No
Is Q4473
OK?
Change
Yes
Q4473
Yes
Check voltage
on Pin 4 U4501
OK?
Check R4422-5
No
and go back to top
Check voltage
No
on Pin 5 U4501
OK?
Troubleshoot
ASFIC
Yes
Yes
Check voltage
on TP4531
OK?
Change
PCIC
No
Check R4409 &
R4473 and go back
to top
Change Q4441
START
No power
No
Is Vctrl
there?
Change Q4431
Check Q4431 gate(open)
and drain resistances
(11kohm)
Yes
OK?
Is Q4441 OK ?
No
Is voltage drop across
R4497 >4.5V ?
Change U4401
Yes
MOSBIAS_2
Check
PCIC_MOSBIAS_1
Are D4471 &
D4472 OK?
Check voltage
No
Yes
Check Q4421 gate(open)
and drain resistances
(11kohm)
Yes
No
TROUBLESHOOTING CHARTS
No
Check
Check
ASFIC
OK?
Yes
No
Check
PCIC
OK?
Yes
No
Change
D4471 &
D4472
Yes
No
Change Q4421
OK?
Troubleshoot
VCO
No
Yes
Is drive from VCO
>+4dBm?
Do visual check
on all components