Nonfunctional A Button

[topaz frigate]

Just picked up this GBC that was a fair bit dirty before I cleaned it up. Came with a Tetris cartridge which I've been using to test, but it seems as though the A button doesn't work (and possibly the Start button if that should select either of the options on the starting screen). I tried cleaning the contacts with a Q-Tip and 70% isopropyl but no dice. The D-Pad seems to work fine (and honestly the contacts weren't any dirtier than they were after I tried cleaning them) so I tried cleaning the actual buttons and the silicone bits but that didn't work either. I'm mostly unknowledgeable when it comes to this console so forgive me if this is a common problem or if I'm completely missing something lol

[trail viper]

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[topaz frigate]

I basically got this for free two days ago when I found it at a donation nonprofit place so I have no idea if this has been modded to any capacity or if it's had any battery acid damage or some such, but as best as I can tell neither is the case

[grand barn]

Hello there
Do you have a multimeter to test continuity with the pad ?

[topaz frigate]

I don't believe so ): I would have to double check tomorrow but I'm almost certain the answer would be no

[grand barn]

I highlighted in red the trace of button A

go ahead and inspect it to see if it is broken or oxydised

[topaz frigate]

As best as I can tell everything looks in order? Could be wrong tho

[grand barn]

Two things to try :
contact the A pad with a piece of metal and see if it works like this
To do that you can put everything back together without the A button and pad

If it doesn't work, this time with no batteries, see if the leg on the CPU is properly attach to the pad
You can try to push it ---gently--- with a toothpick for example
If you need help with visual confirmation, use your phone camera zoom, it can make the trick

[topaz frigate]

Yeah, no luck using metal. I'll take a look at the CPU

not entirely sure what I'm looking for but this is that corner

it doesnt seem like anything is improperly attached? again tho basically flying blind lol

[grand barn]

If the leg (first white point from the bottom) is moving when being pushed, the solder failed and the button signal is not going to the CPU

prop your phone on something, zoom in with your camera, and try to push the leg with something like a toothpick

[tall totem]

how did you clean the button membranes? have you tried wiping the black carbon contacts on some regular printer paper?

[grand barn]

Thought of the membrane also, but it should not be the problem if they used metal to test the button

It would be best if you could find a multi-meter
Ask a neighbor ?

[tall totem]

with Tetris, the A button does nothing until start button is pressed once to select 1 or 2 player mode, so that's also something to be taken into consideration

select also chooses between the two options, so if that works and start doesn't and if flipping the membrane around doesn't have any effect, then there's def something with the actual button connections

using metal to short the contacts can be slightly finicky, but if it doesn't work at all then a multimeter would be good to have

[grand barn]

Oh god I hope it's not the Tetris menu 🫠 Good catch

[topaz frigate]

THANK YOU
I would have never known that 😭😭😭 I SWEAR on my mother's life I tried that at least twice and it didn't work

I literally did try that at least a few times, idk why it didn't work then
Thank you though 🫠 sorry for the trouble

[tall totem]

haha, no problem! glad it turned out to be working fine :)

[grand barn]

oh god it was that 😬
Well the start button is a bit weird since it's made with only mushy silicone