X31 3.3v capacitor failure: hack

[stevec77]

After reading kuzyatech's blog about common problems with the x31, I've done a hack which doesn't include trying to add a surface mount cap. Which I don't feel I have the skills and tools for to avoid damaging other components
https://kuzyatech.com/fixing-an-ibm-thinkpad-x31

So... We got a radial capacity at 470uF (didn't have a 330uF) and transplanted it on top. Now we've filed out a hole where the bottom case standoff usually goes in, so we can hide a shielded radial cap in there.

Yes it's a hack but it's come back to life... Now I just need to replace the hard drive!

Seeing that bios post was bliss! Will post photos when I can

[kfzhu1229]

Nice find! Granted the position of the cap is a bit less than ideal, I'd just like to point out it is totally possible for you to remove and change it with just an amazon soldering iron. You just first heat up the less obstructed side, and then try to lift it with tweezers, and then you touch the other side and it should pop right off. A photo before the operation comes in handy in case you knock something loose. I've changed the tired 3.3/5V filtering caps on several other models like HP Compaqs and Acers before in the same manner with success.
You may have to be a bit careful with that approach though as a 470Uf cap plus whatever effective capacity is left inside of the original is most probably double the rating of the design, which will create an effect where the IC has to drive the MOSFETs a bit harder to overcome the fact that these caps take more to charge up, and cause extra stress on the driver IC and MOSFETs. So, you can keep using it right now as-is, but I recommend you have the caps back-ordered or ripped off another dead motherboard and have them ready to swap when you get them.

[stevec77]

Thanks for that! I did downgrade it to a 330uF radial but from what you've said I think I might look at the surface mounts again. Perhaps I'm a bit too fearful of my gun skills.

[kfzhu1229]

Thanks for that! I did downgrade it to a 330uF radial but from what you've said I think I might look at the surface mounts again. Perhaps I'm a bit too fearful of my gun skills.

again, you don't really need a hot air gun. A soldering iron can take that off perfectly fine, just go slow and go one side at a time.
Also the fat contacts of the surface mounts does help a lot with the filtering quality in use cases like this

[stevec77]

I might try that out next weekend then. I do have a cheap soldering iron. Might also see if I can use another old board for practice

Thanks again!