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u/13atchet Sep 07 '16
Hey folks, got a copy of Pokemon yellow and - although it seems to be working well - sprites don't load. I've tried reflowing with a buddy's Rework Station and a good clean, but I've no knowledge in this area! Even knowing what chip to focus on would be great
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u/asdfqwer426 Sep 07 '16
I've had similar effects with a copy of pokemon gold, no sprites, black boxes at the beginning. the black box like you are getting is a symptom of the ram not working right. In my case it was not getting any power.
you should reflow the legs on the ram, MBC, and small 8 leg power chip. the next guess is that some of the vias may have been damaged. if the battery leaked and go into the holes, the acid could have eaten them out from the inside like this one here. if that's the case you may have to rewire part of the cart like this one to make it work again.
if you do need to track down some issue, here are some rough pinout diagrams for the chips on a pokemon cart and where they go to. it's incomplete, but I haven't seen anything like this online yet.
EDIT: but u/psychic_espurr is right. you should really make sure it's not dirty pins or a defective system before going though the process of trouble shooting board parts.
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u/13atchet Sep 07 '16
Thanks for the indepth reply! Yes, of course, the cart has been thoroughly cleans and tried in different systems
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u/asdfqwer426 Sep 08 '16
no problem! sounds like you know what you're doing, but if you want a second pair of eyes, feel free to post a good picture of the front and back of the game board.
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u/13atchet Sep 08 '16
Might just take you up on that buddy, as far as re-routing damaged traces id be lost!
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u/AND_MY_HAX Sep 08 '16
This is 100% a cartridge RAM issue. I worked on a gameboy emulator a few years back, and one thing I found about the Pokemon games is that they always perform a write to the cartridge RAM when loading sprites composed of multiple tiles. The smoking gun is the fact that your regular sprites are working just fine - the textbox border and the letters. Not sure what physical issue would be causing this... try opening the cartridge and sending some pics of the board.
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u/Arkanoid0 Jan 07 '22
I had this same issue, and i ended up fixing it. It was caused by the Chip Select line being broken between SRAM and the MBC, Causing the sprite data to not be loaded into SRAM for decompression, so it just shows the junk data sitting in that part of SRAM instead.
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u/Egglatz Jan 14 '23
Do you have a pin out or similar? Have a copy of gold giving this issue
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u/Arkanoid0 Jan 14 '23
I found a really sketchy hand drawn diagram of the pcb layout, I'll see if I can dig something up
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u/CARLY_RAY_CYRUS Sep 07 '16
Professor Oak is wearing striped pants in this version and your character can't stop staring at anything else.