Lenovo L580 20LW-0010GE shuts down after a few seconds

[solveit68]

Hello together,

I am hoping for some tips here to repair a notebook.

The notebook has following issue:
After starting the notebook it shut down after a few seconds.
Sometimes it is possible to enter the bios but then after, another few seconds it shuts down also.
The time until shutdown varies slightly.

What I've tried so far:
- cmos cleared
- removed all components that are not essential for motherboard testing including keyboard and touchpad
- ram exchanged
- same behaviour with power supply or battery
- cpu head conducting paste replaced (heat pipes seems to be cold or max. warm at shutdown)
- bios battery checked

Do you have any idea what could be the cause of this?
Bios?

Thank you.

[mon2]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

Remove all power -> meter in resistance mode -> check the resistance to ground of each coil (inductor). Perhaps some cap that is starting to fail and will cause a higher current source event which will trigger the power rail to shut down.

[mcplslg123]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

Visual inspection under microscope may yield some ccorrossion,rotten element.

[solveit68]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

Today I've measured the following values:

5V - 1.7K (first - usb)
1.2V - 490Ω (without DDR4), with 1 DDR4 about 127Ω
3.3V - 0.9K (cmos)
5V - 1.7K (second - standby)
0.7 - 1.6V - 6-8Ω (CPU?)
1.2V - 6Ω (first)
1.2V - 6Ω (second)
0.8V-1.1V - 22Ω
1V - 40Ω
9.2V-12V - 20K (battery)

Today, the device stayed on for up to 3 minutes.

[solveit68]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

I also could not find anything conspicuous during the visual examination.

Are all voltages and currents monitored or could some be excluded?

[solveit68]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

What I also noticed today is that the shutdown is sometimes incomplete. The power LED stays on and you can't turn the device on or off.

[Sephir0th]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

My friend without confirmed relations to the present power supplies we almost can't assume anything from the shared values.

However, a +3VALW which reads below KiloOhms on the load side is already suspicious, Also 1.2V at the load of +VCC_CORE would be a bit odd. To high for classic design and to low for FIVR.

It probably won't be possible to fix it without advanced knowledge how the circuits works and are connected together.

[mcplslg123]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

What I also noticed today is that the shutdown is sometimes incomplete. The power LED stays on and you can't turn the device on or off.

Check DC-DC convesrion load switches. If you have spare one,consider replacing.

[solveit68]

Re: Lenovo L580 20LW-0010GE shuts down after a few seconds

Thank you very much for your tips, I will follow them up next weekend.