Dell E5440 completely dead

[Spider1211]

Re: Dell E5440 completely dead

Remove PU701 and check. It easier and less time consuming than the other methods. Just do not power the board with the chip removed.

[Sephir0th]

Re: Dell E5440 completely dead

Once i Had a partial shorted 5V Rail which was also drawing almost nothing. However the VRM Controller got Mad hot. Case solved.

But yeah i won't expect a massive consumption.

[Andreasbest]

Re: Dell E5440 completely dead

I removed the PR400 and see 20Ω only from the side that is connected to PQ400, the other side is fine (~1kΩ)

[Spider1211]

Re: Dell E5440 completely dead

Check PQ402. Also try removing PU402 and check again. 1Kohm seems a bit low.

[Sephir0th]

Re: Dell E5440 completely dead

So it is indeed +SDC_IN which is shorted. Still PU401 und PU701 Most suspicious in my opinion

[Spider1211]

Re: Dell E5440 completely dead

Check PQ402 and PQ400. Also try removing PU402 and check again. 1Kohm seems a bit low.

Btw, did you also remove PU701 before removing PR400?

[Andreasbest]

Re: Dell E5440 completely dead

No, only PR400 removed, i want to keep the PU701 option last
I'm not too good at soldering QFN

[Spider1211]

Re: Dell E5440 completely dead

Resolder PR400 and remove PQ400. Check which side is 20Ohm. If Drain side (pin 5,6,7,8) of PQ400 is 20Ohms remove PU701.

[Andreasbest]

Re: Dell E5440 completely dead

Resolder PR400 and removed PQ400 and now the funny part begins.
The 20Ω remain on all three Source traces.
Drain and Gate are fine with 40KΩ and 8.4MΩ.

[Spider1211]

Re: Dell E5440 completely dead

Remove PU402 and check again. If it's still same then remove PU701.

[Andreasbest]

Re: Dell E5440 completely dead

Removed PU402 but the 20Ω remain on Source traces of removed PQ400

[Spider1211]

Re: Dell E5440 completely dead

PU701 it is then, as suspected initially.

[Andreasbest]

Re: Dell E5440 completely dead

Ok, gonna try replace it and report back

[Spider1211]

Re: Dell E5440 completely dead

Just remove pu701 and check resistance first. Also make sure not to power the board without the controller chips soldered!

[Andreasbest]

Re: Dell E5440 completely dead

Goodmorning!
I resolder PQ400 and PU402 and removed PU701.
The 20Ω on all Source pins of PQ400 are gone, now it's ~220KΩ
Are we ok with it?

[Spider1211]

Re: Dell E5440 completely dead

Thats great! This confirms a faulty PU701. Replace it and you should be good to go.

Also, with PU701 removed recheck the point where you measured 1Kohm initially and see if its still same

[Andreasbest]

Re: Dell E5440 completely dead

Now shows several MΩ, probably fine?
Also I have CD3301B available from donor board, report in a while

[Spider1211]

Re: Dell E5440 completely dead

Very fine. Good luck!

[Andreasbest]

Re: Dell E5440 completely dead

Ok, solder it succesfully and i see power LED light on BUT only for 1 second, then goes off.
Seems like i have another issue or something is not soldered right?

[Spider1211]

Re: Dell E5440 completely dead

Dell will power cycle a few times before booting (usually around 3 times). Try this: plug in charger, wait 1 second then remove charger. Wait another 1 second then plug charger back in and try to power again (it should power cycle then boot)