Service Forum

[suandmarc]

I would like to repair the charge circuit on my mainboard, but have no technical info on the circuit used. Battery used is known good and charges appropriately in a different ThinkPad.
There are no other known problems with the mainboard (FRU 26P8399).

Any and all advice appreciated.

Regards

[victor]

I can't tell you what is the faulty component by just guessing. I need to know more about it and have the board in front of my eyes.
I can only advice you to check:

1. all fusibles (they are noted with "F", some are translucid, white, blue). Check all power resistors and bridges.
2. all power mosfets, including drivers. Most of them are IC with 8 legs.
3. The logic circuitry that manages the power supply, including logic signals.


Good luck.

[suandmarc]

Hello,

Thanks for the reply.

I have been hoping to obtain enough documentation to properly pursue this issue, but haven't been able to identify all the components because of apparent "in house" part number markings which are yet to be identified. Some day I would like to find schematics or other drawing which help with troubleshooting these mainboards.

I wonder if such data is available anywhere?

Regards,
Marc

[victor]

I didn't find it. Also I had some contacts with IBM personel and they seem to not have the documents, the boards are not refurbished by IBM (not anymore, at least).
The majority of power controllers are manufactured by Maxim, for P4 Max1901 is largely used in TP 30-40 series. The rest are power drivers or power mosfet (usualy marked like 4402, 4404, if I remember well).
Take a look here (click on the map to see Maxim ICs and application for battery pack and power management.
http://www.maxim-ic.com/solutions/notebook_computers/index.mvp

Cheers.

[suandmarc]

I appreciate the tip. I'll check into that.

Regards