Dell E5440 completely dead

[Andreasbest]

Hello!
I got a Dell E5440 that is completely dead, charger doesn't detect any shortcircuit so remains lit when i plug it on laptop.
No signs of life at all, i only detect some heat on PQ4.
Plus PQ4 has 19v on pins 1,2,3 & 4 and only 1.8v on the other.
I replaced it but no luck, same behavior.
Any help appreciated, thank you in advance!!!

Schematics and Boardview attached

[SMDFlea]

Re: Dell E5440 completely dead

check PR14,PR20,PR21,PR533

[Andreasbest]

Re: Dell E5440 completely dead

check PR14,PR20,PR21,PR533

Hello!
Check resistance OR short to ground?

[SMDFlea]

Re: Dell E5440 completely dead

resistance. Desolder and leave them on 1 pad to test

[Andreasbest]

Re: Dell E5440 completely dead

PR14 1MΩ
PR20 10KΩ
PR21 not present
PR533 47Ω

[Andreasbest]

Re: Dell E5440 completely dead

bump

[mielta]

Re: Dell E5440 completely dead

Hi
Check PQ400 and check short to ground on PR400

[Andreasbest]

Re: Dell E5440 completely dead

Hi
Check PQ400 and check short to ground on PR400

Hi and thank you
Neither PQ400 or PR400 have short to ground
I don't think there is a short to ground because charger remains lit when i connect it to MB, if shortcircuit occurred then charger would go immediately off.

[mon2]

Re: Dell E5440 completely dead

1) voltage @ PQ4 1-2-3 ?

2) voltage @ PQ4 (pin 4 = gate) ?

3) voltage @ PQ4 (pins 5-6-7-8) ?

4) Remove all power. Meter in resistance mode.

a) resistance between 1-2-3 (source) & pin 4 (gate)

b) resistance between source & drain (5-6-7-8) ?

c) resistance between gate (pin 4) & drain (5-6-7-8) ?

[Andreasbest]

Re: Dell E5440 completely dead

1) PQ4 1-2-3 pins 19.5V
2) PQ4 4 pin 18.8v
3) PQ4 5-6-7-8 pins 1.87v
4) Done
a) PQ4 1-2-3 pins to GND 70KΩ & pin4 230KΩ
b) Source (black probe) to drain (red) 113KΩ
c) Gate (black probe) to drain (red) 323KΩ

[mielta]

Re: Dell E5440 completely dead

is it possible that PR21 has been lost.
Because PQ4 is a P-channel mosfet and the gate should
have about 10v. If PR21 were there it would form a voltage divider with PR14 at which about 9.5V would be. thus PR4 could switch

[Andreasbest]

Re: Dell E5440 completely dead

The problem is that according to boardview the PR21 is not where it susposed to be, on both sides.
I'll upload photos of MB and screenshot of Boardview.

[mon2]

Re: Dell E5440 completely dead

1) unable to view the posted .brd file

2) with PR14 removed, what is the voltage on GATE (pin #4) of PQ4 ?

[Andreasbest]

Re: Dell E5440 completely dead

1) unable to view the posted .brd file

2) with PR14 removed, what is the voltage on GATE (pin #4) of PQ4 ?

1) Have you try with Allegro? Needs some "refining" to show boards properly.
Here-> https://www.badcaps.net/forum/showpo...0&postcount=38 (thank you @Spider1211 !!! )

2) I'm away from the bench for some days, i'll check it Monday morning and let you know.

Check the boardview meanwhile and let me know if that worked.

[EP3RROR]

Re: Dell E5440 completely dead

Had the same happen with one of two 5440 i had.
Never managed to get to the bottom of it.
i still have the board lying around!

[Spider1211]

Re: Dell E5440 completely dead

I don't think there is a short to ground because charger remains lit when i connect it to MB, if shortcircuit occurred then charger would go immediately off.

Not necessarily. Check for short on all coils just in case and report back.

[Andreasbest]

Re: Dell E5440 completely dead

Not necessarily. Check for short on all coils just in case and report back.

Aloha Spider!
I'll do it Monday morning and report back.

[Andreasbest]

Re: Dell E5440 completely dead

Not necessarily. Check for short on all coils just in case and report back.

Hello again.
PL5 one side is indeed grounded but i think is normal, all rest coils are fine, no shortcircuits to ground.

[Andreasbest]

Re: Dell E5440 completely dead

1) unable to view the posted .brd file

2) with PR14 removed, what is the voltage on GATE (pin #4) of PQ4 ?

With PR14 removed i still get 18.8v on pin #4. No change.

[Sephir0th]

Re: Dell E5440 completely dead

Hello again.
PL5 one side is indeed grounded but i think is normal, all rest coils are fine, no shortcircuits to ground.

Afaik PL5 should Show short to GND at both Sides. What is the internal resistance of PL5.