Motorola 6864115B62-C

3-6 TROUBLESHOOTING CHARTS
3.0 Troubleshooting Flow Chart for UHF 40W Transmitter
No
Is Q4441 OK ?
Yes
Is drive from VCO
>+4dBm?
No
Is voltage drop across
R4497 >4.5V ?
No
Check Q4431 gate(open
)
and drain resistances
(11kohm)
No
Check Q4421 gate(open)
and drain resistances
(11kohm)
No
Check
PCIC_MOSBIAS_1
No
No
Change
Q4473
START
No power
Is Vctrl
there?
Is Q4473
OK?
Check voltage
on Pin 5 U4501
Check R4422-5
and go back to top
Troubleshoot
ASFIC
Check voltage
on TP4531
Change
PCIC
Check R4409 &
R4473 and go back
to top
Check
MOSBIAS_2
Check
ASFIC
Are D4471 &
D4472 OK?
Change
D4471 &
D4472
No No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Check
PCIC
Yes
Change Q4421
Change Q443
1
Yes
Change U4401
Yes
Do visual check
on all components
No
Change Q4441
Troubleshoot
VCO
No
Check voltage
Check voltage
on Pin 4 U4501
OK?
OK?
OK?
OK? OK?
OK?
OK?