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 Post subject: Corroded DDP DOJ crashing at start of game
PostPosted: Mon Aug 13, 2018 5:51 pm 


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Joined: 08 Jan 2016
Posts: 439
Location: San Jose, CA
I got a DOJ just last week from here, and after buying saw that the seal was intact and the battery had never been removed. As expected, the battery had started to leak, but it didn't look too bad - after all, this was sold as a working board.
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I clipped the varta, and swabbed everything off with alcohol for the time being. I am out of vinegar so I will have to get some in order to neutralize it properly.
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Unfortunately, as-is, the board will power up and appear to work, but right after the character select, the game will crash. This is the point where the dialogue box pops up with the weird doll-language shit, and the bottom door opens up to reveal the first stage.
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It is worth pointing out that there is minor discoloration in the graphics for the door as well; a few tones will usually have a strange purplish tint, though I've seen brown once. It is not consistent.

I believe it is crashing because it is loading junk data for the stage. The same crash happens at the start of the DEMONSTRATION screen - it'll crash before any of the stage is shown.
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I socketed U13 and made sure no traces underneath it are corroded, but it looked fine. All traces show continuity to this chip.

The custom IGS 026 looks to be input-related, and is doing its job as far as I can tell. I don't know enough about PGM architecture to point towards the source of the crash. The error handler is kind of useless here, since it's printed the UI but none of the actual addresses associated with it.
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 Post subject: Re: Corroded DDP DOJ crashing at start of game
PostPosted: Tue Aug 14, 2018 9:04 am 


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Joined: 03 Nov 2009
Posts: 23
Sorry for your loss dude. At least, i tried to warn you, there was no way this could end well :roll:

Got mine around 2008, it died one year later because one trace was slightly corroded. I was able to fix it with a bridge, removed the battery and cleaned everything. Finally, around 2014, i got the exact same screen you have after ship select. It's weird to this now, as it only appeared once, but i was so shocked that i can't even forget that image in my head. Rebooted, got random yellow number. Rebooted once more, and it was for me dead (showing the infamous "Memory : node use" that everybody seemed to have, sometimes just random garbage)

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First things first, you got to clean your board. Use Isopropanol, but i'm not sure about vinegar, some people tell that it's ok to remove acid, some says it's another acid and you have to use baking soda ... i don't know anything about chemistry, but it's just a warning. Just to give you an idea, this is how clean my board was when it died, in comparaison, and still got the very same problem you descirbe :

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Seeing it again now, i can see within seconds where it fails, just on the right of the "BT1" instructions. On yours, there's so many places you'll have to do continuity checks before even thinking of a dead component that it's gonna be a long work.

The "good" news is, PGM slots are really really low on price nowadays, and you can probably salvage one to get some part if needed, what was impossible or really expensive back then.

I know some people were able to fix it, i can only provide you with theses (omg) nearly 10y old threads i case you missed theem. Most pics are probably dead, but it's still the best source of info you'll get on this :

https://forum.arcadeotaku.com/viewtopic.php?f=26&t=5549
https://forum.arcadeotaku.com/viewtopic.php?f=26&t=5170

Hope you'll find a way to fix this.


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 Post subject: Re: Corroded DDP DOJ crashing at start of game
PostPosted: Tue Aug 14, 2018 7:12 pm 


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Joined: 08 Jan 2016
Posts: 439
Location: San Jose, CA
Unfortunately it didn't even occur to me what the meaning would be of a new seal on such a board until it was too late : |

As for the board, a lot of the brown-looking areas are dirt that has entered in more natural ways. A lot of that came off with no trouble with some isopropyl alcohol and cotton swabs.

The board is generally quite clean, aside from the obvious corroded area. Last night I put a lot of time into cleaning more of the area aggressively, and I re-flowed every pin on every custom and RAM with no change, unfortunately. I checked some traces which go near or through the corroded area but they all check out and are just fine.

Your board looks much cleaner than this one! I'm hoping to hook up a logic analyzer and detect where the game is actually crashing. That might help point towards a particular chip having failed.
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 Post subject: Re: Corroded DDP DOJ crashing at start of game
PostPosted: Wed Aug 15, 2018 8:17 am 


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Joined: 03 Nov 2009
Posts: 23
If you were able to reflow and use a logic probe to find what chip is faulty, your knowledge is above mine, so all i can do is wish you luck.

Feel free to share any discover or repair log you have, many people around had similar troubles, it might help at some point.


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 Post subject: Re: Corroded DDP DOJ crashing at start of game
PostPosted: Mon Oct 08, 2018 6:23 pm 


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Joined: 08 Jan 2016
Posts: 439
Location: San Jose, CA
Update on this: I think it's just the RAM. I put the CPU on the LA and found it spinning in the loop that results from the error message printer and traced back. This error screen is generated by errors in the game engine, not exceptions on the CPU. Frustratingly, the printing function for the error seems to be dummied out, as the missing program counter, registers, etc. are actually printing space characters. I verified this by watching writes to the VRAM and caught each letter being printed. 9040D8 is the address for the "E" of ERROR, followed by 9041D8 for "R", so on and so forth.

I moved the RAM chips around (since I do not have spares yet) and the error changed. Palette issues disappeared, and I am able to get in-game. It crashes later on in the level, but that makes me sure one of these RAM chips is bad. I'm going to just replace all four.
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 Post subject: Re: Corroded DDP DOJ crashing at start of game
PostPosted: Tue Oct 09, 2018 2:13 am 


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Joined: 26 Mar 2008
Posts: 1293
Location: philly suburbs
Glad it looks fixable. Sucks when you get an expensive board and it has a problem.


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