GB Color with Battery Damage, Up and Left inputs not working

[cedar lodge]

Hi folks! I have been working on repairing my late grandma's GB Color. The battery damage when I received it was so bad that the one lead had corroded off the connection. I just successfully (though not super clean-ly) replaced the battery connections and it does turn on and work again. Huge progress!

However, what became clear immediately is that the buttons seem to also have some issues. By my eyes all the pads and gold spots (blanking on the name) are very clean and looking good. The only thing at this point I can see is that some of the thru holes on the board are gummed up with blue battery goo. I've cleaned up as much as I can possibly reach, but the inputs still aren't working.

I've rotated the silicon pads 180 degrees and it is still the up and left inputs, so I think I can rule out that being the issue. Will add some photos after I post, but I wonder if anyone has any theories or additional steps to try?

[pastel stream]

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[cedar lodge]

Second image with screwdriver to point to the thru holes which have some battery goo still lodged in there. There are others around the board that also have some, but it's all very minor. That's not to say it's not causing a problem, but it's difficult to see in a photograph.

Full board for reference. I’m pretty rough at soldering so yes that’s my solder job on the battery connection next to the speaker

[hot hemlock]

Hey @cedar lodge 🙂
Could you give us pictures of the other side of the board ? Please make it right side up for ease of use 👍

[cedar lodge]

certainly!

[hot hemlock]

Do you own a multimeter ?

I can already tell that you have some corrosion in the vias around the terminal you repaired (blue dots)

[cedar lodge]

I do not own a multimeter, but I imagine I might have access to one if I ask around

and yes, that's correct - there is some corrosion in several of the vias around the board

[hot hemlock]

It will be needed to proceed with testings
Let's see if we can spot obvious things other than the vias

Can you take another picture like the previous one but for the other side ?
There's a lot of reflection on an area I'd like to inspect

[cedar lodge]

yup

Tried to get the glare in a different spot lol

[hot hemlock]

All the vias I spoted are going to the ground plane so it's not the end of the world, even tho you need to clean them with vinegar

As for your left + up issue, it didn't jump out at first but it seem P01 and P02 are missing from the board
Possibly corroded away ? But the area seem quite clean
The issue is, on the CGB-CPU-02, the test pads are in-line with the lanes, meaning : no test pas, no continuity

Can you confirm what I'm seeing ?

[cedar lodge]

I see P01 and P02 - yeah those were blank when I cracked open the GB initially to start cleaning

It's very likely that they corroded away - again the power connector I (poorly) replaced had completely severed from the board it was corroded so badly. Edit: I should also note that the corrosive battery acid had settled under the d-pad's rubber membrane right where P01 and P02 are on the board now that I'm looking back at the cleaning I've done

I can do some vinegar cleaning on the ground vias for sure

Seems to me like that is either an impossible fix or a very difficult one? That is, replacing the P01 and P02 test pads

[hot hemlock]

This is what the board looks like, except your pads are in-line
They branch away on this picture

You will need to

1. protect your golden pads with kapton tape
2. scrape away the mask on the lines to expose some copper, but not expose the ground plane around it (craft knife scraping)
3. solder a thin piece of wire on the exposed line

[cedar lodge]

ooof - I understand both what you're showing me and what needs to be done and that is well beyond my skill level haha

thank you so much for your help so far by the way! I would have never guessed that those two locations were noteworthy (P01 and P02)

[hot hemlock]

where are you located ?

[cedar lodge]

I'm in the United States

[hot hemlock]

We have some good people there, they could take the job

[cedar lodge]

my fingers are crossed - I do not remotely have the steady hands needed for a job like this haha. But thank you again for all your help identifying the issue! I have hope once again that I can get it working

[hot hemlock]

It is not too hard to do, and if you just protect your golden pads, there is very little that can go wrong
Since yo already repaired your battery contact, I think you can do it

That said it is OK not to take the risk
Would you like a US modder to get in touch ?

[cedar lodge]

hmmm. maybe! I think the odds of me pulling off such a precise job is really low. The battery contact was huge in comparison lol

[hot hemlock]

Scrape away some of the mask on the line, do it slow
Tac one side of the wire, the wire won't get soldered anywhere else than the scrapped area
The other side is easier because the wire is already attached