Dell E6440 shortcircuit

[Andreasbest]

Hello!
I have 2x E6440 with the same issue, charger goes off when plugged in laptop, indicating a MB shortcircuit.
Nothing wrong by a simple eye inspection, so any help appreciated.
Whatever you suggest me i will try it in both motherboards.
Thank you in advance!!

[Andreasbest]

Re: Dell E6440 shortcircuit

none? Don't tell me you are all on vacation! XD

[mon2]

Re: Dell E6440 shortcircuit

Start with PQ4 mosfet. Meter in DC volts mode. Post the voltage reading on each pin of this mosfet. Measure carefully.

After this, power down. Meter in resistance mode (200 ohms). Post the resistance to ground for each pin. Red meter probe on mosfet; black probe to any ground.

(Back to sleep...it is 2:47 am here. Will check back later for your post)

[Andreasbest]

Re: Dell E6440 shortcircuit

Start with PQ4 mosfet. Meter in DC volts mode. Post the voltage reading on each pin of this mosfet. Measure carefully.

After this, power down. Meter in resistance mode (200 ohms). Post the resistance to ground for each pin. Red meter probe on mosfet; black probe to any ground.

(Back to sleep...it is 2:47 am here. Will check back later for your post)

Hello.
Thank you helping me!
All voltages are 0v (since charger goes off immediately after i plugged it in MB)
All resistances are 19.5ΚΩ

[mon2]

Re: Dell E6440 shortcircuit

Confirm the voltage at coil PL5 pin #1.

Is your adapter confirmed to be ok?

You should see the adapter voltage at the dcin connector on the logic board. Unless there is a short at the connector stage, the hot voltage should be present and not be 0V. A short circuit will force the external power adapter to turn off.

If possible, detach the power adapter and check the adapter output while it is out of the logic board.


Is your laptop battery still with a voltage? Value?

Post your voltage readings.

[Andreasbest]

Re: Dell E6440 shortcircuit

All voltages on PQ4 are ~400mV with charger connected and turned off.
Yes charger is ok, i use it in all Dell and works fine, only these 2x E6440 have issues.
Battery is charged, i don't know it's voltage though.
Meanwhile i'm searching for PL5...

[SMDFlea]

Re: Dell E6440 shortcircuit

All voltages on PQ4 are ~400mV with charger connected and turned off.
Yes charger is ok, i use it in all Dell and works fine, only these 2x E6440 have issues.
Battery is charged, i don't know it's voltage though.
Meanwhile i'm searching for PL5...

Find PL5 in the boardview https://www.badcaps.net/forum/showpo...41&postcount=8

[Andreasbest]

Re: Dell E6440 shortcircuit

Yes this is what i'm trying to do but none of the boardviewers i have can open this .cad file

[SMDFlea]

Re: Dell E6440 shortcircuit

Yes this is what i'm trying to do but none of the boardviewers i have can open this .cad file

BoardViewer will open it, its not as slick as openboardview but its ok -

http://boardviewer.net/

[Andreasbest]

Re: Dell E6440 shortcircuit

Ok found it. Next to DC jack.
The same ~380mV on both pins

[Andreasbest]

Re: Dell E6440 shortcircuit

BoardViewer will open it, its not as slick as openboardview but its ok -

http://boardviewer.net/

It was crashing, needed to set graphics acceleration to GDI, now works fine.

[mcplslg123]

Re: Dell E6440 shortcircuit

Resistance on PR703??

[Andreasbest]

Re: Dell E6440 shortcircuit

Resistance on PR703??

Hello and thank you!
You mean resistance to ground?

[mcplslg123]

Re: Dell E6440 shortcircuit

Hello and thank you!
You mean resistance to ground?

yes

[Andreasbest]

Re: Dell E6440 shortcircuit

yes

PR703 is missing from this MB, any other checkpoint??

[Andreasbest]

Re: Dell E6440 shortcircuit

I attach the schematics for the specific MB i have, LA-9934P just in case they are different with the #1 post.

[mon2]

Re: Dell E6440 shortcircuit

Meter in resistance mode (200 ohms). All power removed / off.

Understand that you have already posted 1-3 but please check again:

1) Mosfet PQ4, what is the resistance between SOURCE & DRAIN ?

2) Mosfet PQ4, what is the resistance between SOURCE & GATE ?

3) Mosfet PQ4, what is the resistance between GATE & DRAIN ?

4) What is the voltage reading of pin # 5 of your adapter - use it in another known good box and post the voltage. This is the adapter ID voltage to inform the logic board of its power rating.

If the adapter is reporting 0V then it is shutting down due to an excessive current draw. Something on this logic board is causing this event. Do you see any high temps on the board? You can pour alcohol on the logic board and search for the part(s) that evaporate the alcohol the quickest.

[Andreasbest]

Re: Dell E6440 shortcircuit

Source and Drain have short cictuit indeed.
Gate-Source and Gate-Drain are normal, no shortcircuit.

Charger goes off due to shortcircuit for sure, i use it on other E6440 with i7 and GPU and work like a charm, no problem on PSU at all.

[Andreasbest]

Re: Dell E6440 shortcircuit

I remove PQ4 and there was no circuit in MB traces, AO4423 though had still shortcircuit in Source-Drain.
I replaced it, shortcircuit gone on PQ4 but still MB has a shortcircuit somewhere that powers off adapter.
PQ4 replacement was half of the fix.

[mon2]

Re: Dell E6440 shortcircuit

Test each mosfet using the resistance mode of your meter and post your updates.