Lenovo B51-80 green led flashing shortly

[darkm4n]

Hi,

I am trying to repair a dead Lenovo B51-80 laptop, currently with the battery connected it doesn't power on, it's completely dead, when I connect both battery and charged the green led near the DC input connector stays on but the green led from the bezel stays on for about 2..3 seconds than quickly flashes once than again stays green for another 2..3 secs and the sequence is repeating itself, the laptop does not power on.

I did search for a schematic/boardview and could't find any and I don't have much experience with Lenovo laptop boards. I could't find any short on a quick look and also no visible damaged parts.

Does anyone have any ideea that could point me in the right direction ?
I believe the charging and power circuit is similar to the B50.


Thanks!

[mon2]

Re: Lenovo B51-80 green led flashing shortly

Hi. There are many B50 schematics in my database.

Can you identify which schematic you are referencing ?

LA-B091P ?
LA-B092P ?
LA-B101P ?
LA-B102P ?
and there are others...

[darkm4n]

Re: Lenovo B51-80 green led flashing shortly

Hi mon2,

This is a B51-80, not a B50.
I did find a schematic online for B51-80 but it seems it's missing the charging circuit and boardview is not available anywhere.


Thanks!

[mon2]

Re: Lenovo B51-80 green led flashing shortly

We don't need no stinkin schematics...review where the DC adapter mates to the logic board.

There you will see (most likely) 2 large mosfets and a charger IC nearby.

Post the markings of the mosfets & charger IC that will be linked to these mosfets.

First, is your battery known to be good ? What is the history of this unit ? Just decided to not work or liquid damage ?