Thank you very much for the clear cut answer.
This helped me a lot.

I checked some test points and yes indeed, there is connection where i thought could not be because of the missing resistor.
May you have a very good day....

My board:
LA-E921P
Rev 1B

Schematic in use
LA-E921P
Rev [B]1A[/B]

Think i got both schematic/boardview from external site.My board:
LA-E921P
Rev 1B

Schematic in use
LA-E921P
Rev [B]1A[/B]

Think i got both schematic/boardview from external site.My board:
LA-E921P
Rev 1B

Schematic in use
LA-E921P
Rev [B]1A[/B]

Think i got both schematic/boardview from external site.

Having some trouble understanding how compnents like resistors /caps etc that are present in board view and schematics but are missing on the actual board iam troubleshooting.
In my case its about some resistors /caps around the charging ic.

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For what it's worth:
Since i installed dual system (win10/ linux mint) i can now confirm that:
once you put the machine into sleep and then waking it up --> error melody is gone, no matter how many times you press FN or FN combos, at least until the next reboot.
This behavior is the same both in win10 and linux mint....

After further research i decided that i's maybe better to put this error 0288 troubleshooting thing on hold.
There are strong indications that the error (in most cases) is caused by the bios itself.
Lots of people have had this issue even with laptops out-of-the box, others say that after bios [B]update [/B]to version [B]1.17 and above [/B]the issue occurred.

Lenovo even had a specific fix that reads:

[B]- (Fix) Fixed an issue where BIOS might generate 0288 beep error.[/B]

They maybe fixed it in some models, but it seems to be still baked into...

Ok I did the stress testing mentioned obove [B]not[/B] in normal windows enviroment, but via an bootable toolkit (hirens boot cd like toolkit).
After running same software [B]within[/B] windows no errors accured.
Also run other tests like furmark, heavy load etc. Everything's fine, no errors.

As soon as can locate the fuses i will test.
Not that easy, since total beginner, but try my best.Ok I did the stress testing mentioned obove [B]not[/B] in normal windows enviroment, but via an bootable toolkit (hirens boot cd like toolkit).
After running same software

I maybe discovered something interesting.
The heat sink was bent when i first opened the laptop. Specifically, the "tube" that goes to the fan.
I bent it back but the tube is of course not in its original form. It is bottle necked so to say.
Some user in the depth of the internet made a comment on my specific error (0288) but did not elaborate further.
He said it is caused by faulty temperature sensor(ing).

That would make more sense (for me at least), since the official error description is -> faulty display or lcd cable or both).
But my...

Indeed there is neither backlight nor picture with connected display cable, moreover, no acces to bios, no caps lock led or num led (upon pressing) and no error-melody.

Hi.
I bought a defect laptop for training porpus (maiboard troubleshooting /repair etc).
As advertised by the seller it turns on, fan spin but no display.
First thing i did was disconnect anything (ribbon cables) that could eventually cause the display not to work.
Still no display, not even via hdmi.
But after removing display cable off the mainboard it worked "perfectly" fine via hdmi.

So i installed a spare ssd and installed win10 without any issues.
With all the drivers installed via win update and lenovo vantage i went back to bios...

Hello badcaps community.

I'm here for learning.
Found this forum after research for my little project.
My knowledge of electronics is very little but i try to learn a bit at a time.
Would love to learn how to read and understand schematics for mainboards etc in the long run.
Thank you....