T540p no power

[RethoricalCheese]

Issue: No power
Possible reason: Slight liquid damage (corrosion) on C8286/C8285 and near C611.

Damage cleared, seems nice now, but still the same problem. Liquid damage might be just a coincidence.

No power on BIOS chips.
Unable to find 3V3 and 5V ALW.

There is 3V present on power button.

Any idea where to look or is there a schematics available?

[caspian]

Re: T540p no power

what is the mainboard ID?

[RethoricalCheese]

Re: T540p no power

Oh, sorry, forgot to add that:

LMK-1 SWG2 MB
12308-2
48.LO16.021

[RethoricalCheese]

Re: T540p no power

Almost a year later I received another T540p with similar fault.

When I connect the charger, power button blinks 3 times. Laptop will not turn on. 3V3 present on power button, goes low when I press it.

3V3 and 5V are present when battery is connected but there is 0V on both of the BIOS chips. 19V from charger is present. Battery is being charged.

Did not find any shorts on inductors.

CMOS reset done.

I am out of ideas.

[mylocky]

Re: T540p no power

In 2023 this problem is still on. Can you find any solution for that?

[bachir2004]

Re: T540p no power

CMOS reset done.

I am out of ideas.[/QUOTE]

Had one t440 2 hours ago same problem 30 minutes struggling with the mobo nothing like dead not even 3.3v on battery connector,nothing on bios chip.Finally removed the cmos battery plugged in the charger and it ran like normal.reconnected the cmos battery and it still runs ok.Have you checked the two first mosfets near power connector?