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Replacing a missing pin on a PLCC IC

Posted: 04 Mar 2026 19:04
by dml
So in an unrelated PLCC drama (see earlier post), I lost a pin from this FPU.

fpu1.jpg

I would normally throw this in the 'dead parts' bin - but this one has an interesting bug which helps me verify my FPU testing tool. So it would be nice to hang onto it.

I decided to try replacing the missing pin. This isn't super easy because the pin broke off flush with the package. It will involve some drilling. I opted to drill from the underside because it will be easier to support the new pin from behind with an epoxy filler.

fpu2.jpg

To replace the old pin, I picked the leg of a potentiometer. It's definitely a bit wider than the original but it's also not flimsy, which should help. I can always dremel the sides of the pin later to make it thinner.

fpu3.jpg
fpu4.jpg
fpu5.jpg
fpu6.jpg
fpu7.jpg

Finally, some epoxy filled in the cavity behind the pin.

fpu9.jpg




I'm not recommending this as a thing to do - just posting for entertainment purposes. Unless you don't have any other option, better just throw it away and save the socket :D

Re: Replacing a missing pin on a PLCC IC

Posted: 04 Mar 2026 20:43
by rubber_jonnie
I've done similar before, definitely worth a go if the IC is known good.

Re: Replacing a missing pin on a PLCC IC

Posted: 05 Mar 2026 06:39
by russellnash
That is quite a sophisticated repair, well done.