Dell Latitude e6430 problem inversion of polarities

[nejib01]

Hi ,
After polaritie reverse of the power supply my laptop works only without battery (motherboard QAL81 LA-7782P) , can you help me to solve this problem.
Thanks

[mon2]

Re: Dell Latitude e6430 problem inversion of polarities

You will have to review the 2*DCin mosfets.

Remove all power. Meter in resistance.

Check the resistance of the mosfet pins:

Source and drain
Source and gate
Gate and drain

Post each measurement. Repeat for the next mosfet.

[nejib01]

Re: Dell Latitude e6430 problem inversion of polarities

Thanks for replying.
do you mean these two ones near dc input in picture

[mon2]

Re: Dell Latitude e6430 problem inversion of polarities

It is a good start. What are the markings on these 8 pin mosfets?

[nejib01]

Re: Dell Latitude e6430 problem inversion of polarities

4423 / 4435 and i think the second one short (all drain - source - gate make bips on multimeter)

[mon2]

Re: Dell Latitude e6430 problem inversion of polarities

Good. If you have a good replacement for this mosfet, replace it and test again.

[nejib01]

Re: Dell Latitude e6430 problem inversion of polarities

Thanks a lot i found mosfet 4435bz by chance and everything works like a charm ,my laptop detect the battery now .

[mon2]

Re: Dell Latitude e6430 problem inversion of polarities

Well done. Thanks for the thread closure.