Dell E5440 no ldo 3v5v,

[Tend0]

Re: Dell E5440 no ldo 3v5v,

ok

[Tend0]

Re: Dell E5440 no ldo 3v5v,

presence of resistor @ PR425 confirmed
voltage each : pin1 = 0V pin2=2,74
PR425: black wire to pin 1 and red wire to pin2 = 99,6k
black wire to pin 2 and red wire to pin1 = 287k

[mon2]

Re: Dell E5440 no ldo 3v5v,

Can you confirm that BOTH sides of PR425 are @ 0v ? This is not correct since pin #1 should be the same voltage as REGN.

Measure the voltage to ground @ REGN which should be ~6 volts. Confirm it.

Then remove all power -> meter in resistance mode.

One meter probe to pin #1 of PR425 and other meter probe to the REGN pin on the charger IC (PU402).

What is the resistance reading? It should be ~0 ohms since this is what the schematic shows. Confirm it.

Update - I think you updated your post

Can you check the voltage of REGN pin directly ? It should be ~6 volts. The SAME voltage must appear @ PR425.

[Tend0]

Re: Dell E5440 no ldo 3v5v,

yes both side of pr425 are 0V
it look like pr425 pin1 is not connected to pu402 pin 16 REGN
REGN voltage is 5,99V
all power remove and metter in resistance mode
metter red probe to pr425 pin 1 and black prob to IC pin 16 (REGN) it show me OL

[mon2]

Re: Dell E5440 no ldo 3v5v,

Can you check the resistance to ground of PR425, pin #1?

I used my own (PDF) schematic for this review from a paid service.

Can you confirm that your CAD file shows the same? The partial boardview seems to agree with what I see here. REGN should be connected to pin #1 of PR425.

That is, if this pull-up voltage is missing, you could apply a wire from REGN to this PR425 pin #1. Just want to be 100% sure that your board is the same.

Can you see any damaged trace from PR425 pin #1? Worth to review and trace this connection and then use a piece of wire.

Sounds like that there is a broken PCB trace between the referenced pins.

Strange that it was working before with out this connection.

[Tend0]

Re: Dell E5440 no ldo 3v5v,

the resistance to ground of PR425, pin #1 IS OL
i confirm that in cad file PR425 pin1 is connected to REGN
i don't see any damage trace near pr425 and pu402
Maybe before this connection was not broken

[mon2]

Re: Dell E5440 no ldo 3v5v,

Ok - then proceed to use a wire to connect these 2 points and then test again.

[Tend0]

Re: Dell E5440 no ldo 3v5v,

Thank you very much i managed to fix the laptop today based on your help @mon2

[mon2]

Re: Dell E5440 no ldo 3v5v,

Excellent Good job and thanks for the update for a closure.

[Th3_uN1Qu3]

Re: Dell E5440 no ldo 3v5v,

i don't see any damage trace near pr425 and pu402
Maybe before this connection was not broken

Maybe small liquid spill from before and it just happened to break now, it is a high (well, in laptop terms) voltage circuit.