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X31 3.3v capacitor failure: hack

X20/X21, X30/X31, X40/X41 Series
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stevec77
Posts: 9
Joined: Fri Apr 29, 2022 3:24 am
Location: London, UK

X31 3.3v capacitor failure: hack

#1 Post by stevec77 » Fri Jun 07, 2024 5:21 am

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! :roll:

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

kfzhu1229
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Re: X31 3.3v capacitor failure: hack

#2 Post by kfzhu1229 » Fri Jun 07, 2024 9:39 pm

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.
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)

stevec77
Posts: 9
Joined: Fri Apr 29, 2022 3:24 am
Location: London, UK

Re: X31 3.3v capacitor failure: hack

#3 Post by stevec77 » Sat Jun 08, 2024 3:07 am

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
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Posts: 2568
Joined: Tue Sep 22, 2015 10:59 pm
Location: Toronto, Canada

Re: X31 3.3v capacitor failure: hack

#4 Post by kfzhu1229 » Sat Jun 08, 2024 4:19 pm

stevec77 wrote:
Sat Jun 08, 2024 3:07 am
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
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)

stevec77
Posts: 9
Joined: Fri Apr 29, 2022 3:24 am
Location: London, UK

Re: X31 3.3v capacitor failure: hack

#5 Post by stevec77 » Sun Jun 09, 2024 9:51 am

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!

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