GBA SP: B-Button

[Ludwig]

Hello everyone. I thought someone here may know a solution to my issue.

Problem is:
My GBA-SP's B-Button is broken. I guess it's the rubber between button and contact, or the button itself. It just doesn't work anymore. I cut a little circle into a small piece of paper and i put it in between the button and the rubber, this slightly improves the issue, now it occasionally works, and if it does it often triggers multiple times which is undesired.

Does anyone know a quick solution to this? I may order a broken SP for spares to fix it next month, but i would really like to play, so a temporary DIY solution would be a very nice thing.

[RP2A03]

How does the button itself feel. Is it springy or mushy? If it's mushy or the rubber is torn (check carefully), then it needs to be replaced. It may be possible to use the rubbers from another Nintendo controller. The rubbers from earlier GBA and GB systems would probably fit and I suspect that those from the SNES and Wii classic controllers will also fit, although these might be a too big or held to the board differently.

If the rubber feels and looks good then the problem could be dirty contacts. Clean them and the rubber with alcohol. Also try placing a different rubber membrane (control pad will be good enough) over the button contact to see if the problem improves.

If none of this works then the problem could be a cracked board or cold solder joint.

[Ludwig]

I can't say that it would feel odd. I already knew it wouldn't fit but i opened up my GB anyways, and i took a picture. I may check the solder again, but i doubt it, since it probably wouldn't work at all if that would be the case.
http://i394.photobucket.com/albums/pp26/Xaromir/gb-buttons-1.jpg

And here my GBA
http://i394.photobucket.com/albums/pp26/Xaromir/gb-buttons-2.jpg

Those red things are the "solution" i have 3 of them already, but as i said it doesn't work particularly well - sadly.

[RP2A03]

Ummm... wow. While I can't say that I'm surprised that the original GB used NES rubbers, I do find it surprising that the GBA SP has different ones from the original GBA.

What happens if you remove the paper and flip the rubber so that the side that was over B is now over A? Do your symptoms stay the same or are they now inverted? Also, have you cleaned the contacts on the board and the rubber?

[Ludwig]

Sorry for the late answer. I haven't cleaned it so far, but it looks rather clean, i also think the problem rather is subtraction, i can't see a difference between the contact of A and B, they both seem to be fine. Good thinking with the switching, but no, doesn't help. I guess that means it's the button. :|

[Squeept]

The use of the rubber pads in the buttons in the GBA SP is slightly misleading. They do not have carbon contacts, but are instead a buffer to make the pressing of the SMT dome switch on the motherboard more natural / responsive. I doubt the rubber is damaged, the actual dome switch on the motherboard is probably just worn out. Replacing those is difficult if you are not experienced with soldering.

I carry all GBA SP parts including full motherboards (actually, I think I'm out of AGS-101 boards) except screens, so just let me know if you find the problem.

[RP2A03]

I wish I knew that sooner.
In that case it is most likely the button itself and like Squeept said; SMT components can be a bitch to work with. Don't even attempt to replace the button if all you have is Radio Shack iron, you'll just end up destroying the board.