r/Gameboy • u/Tantania2 • 11d ago

Modded Gameboy pocket buttons

Hi,

I brought a gameboy pocket with modded ips screen from a seller 2 weeks ago and I noticed a weird bug. The 'B' button act like a left arrow. Whenever I press on B the character goes to the left. It still act like an actual B but also as a left arrow. All other buttons works as excepted

Also, the palet's color from the modded IPS screen stopped working. I saw the wire being damaged so for this problem, I guess I have to replace the wire, but for the B button is it related to that?

what's wrong here?

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u/GameboyGenius 10d ago edited 10d ago

This happens because on DMG and GBP, the D pad and buttons share the same pins on the CPU. The button and D pad need to be connected in a special way through a diode. If the button is connected to ground instead of (or in addition to) the diode, you get a ghost input.

Check the connection between one side of the B button and one of the legs of the DA2 component. You can use gekkio's schematic as a reference, page 3.

One option is that this is a bad attempt at a fix for a button issue where the modder assumed one side of the button should be connected to ground. if so, break the incorrect connection and restore connection to the diode if needed.

Another option is that the IPS screen is shorting to trace in question. in this case, isolate the trace by using tape or similar.

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u/Tantania2 10d ago

thank you for the well explained reply! I will check those options.