Ugh, the dangers of ebay...I got this Esprade pcb off a guy for about 150 bucks and when it arrived today, I plugged it in and got a screen full of garbled crap and static. After fiddling with the harness position on the board for about 20 minutes, I have it to where the game itself will play with only a little scattered static, but the character select and title/logo screens are really messed up and sometimes just crash. So, while the game is basically playable now, I don't want to have to mess with it for a half hour everytime I switch back to it after playin a different game. Plus it just bugs the hell out of me that I have a game that isn't working 100%.
The contacts are as clean as I can get them(on the board and my harness) and I can't imagine what might be causin the problem. Maybe there's no solution for this but since I don't know anything about pcb repair I thought maybe you guys would have a suggestion.
if not dirty contacts (did you try a pencil eraser?), than maybe a loose chip? you can try gently bending the board (really just exerting pressure on it) to find loose chips or loose solder connections (you've got to be really careful with the pressure to isolate just the right spot).
Sounds like maybe a loose chip or perhaps a broken solder joint on somewhere- perhaps on one of the flat, square proccessor chips (in which case it's really hard to identify and fix- I've identified those but never fixed them, just made them worse).
However, I've got a robocop board that behaves similarly, with lots of garble around the sprites, and I worked on all the chips and connections only to discover that it was just how the JAMMA harness fit on. So maybe there's just something wrong with the connection that you've overlooked (duh, forget all the stuff I just said, if that's how you got it working so far, than surely you've narrowed it down to that- just try flexing the board if you think it could be something else)
Thanks for the suggestions dpful. I tried flexing the board this way and that, and it does seem to make a difference. The character select screen, instead of being covered in white blocks, started showing some of the text and pictures but not all of em. For a moment I had it bent in a way that made the picture show up fine, but I couldn't see which chip was messed up(nothing was sticking up or anything obvious) I guess this means it's a chip.
I tried pushing down on the chips but no good. Guess I'll have to mess around with it some more to see if I can find the problem chip.
My esprade did this sort of nonsense when the board touched the inside metal of my candy cabinet. Then I put the board on a box and everything went okay again.
Its probably just shorting somewhere, or a chip has somehow unsocketed itself or perhaps a trace has cracked. There are a few places on the net that charge to fix pcb's.
This industry has become 2 dimensional as it transcended into a 3D world.
There´s another possibility: the board might be thinner than your other boards, causing the Jamma harness to not have secure contacts. You could try bending the contacts slightly inwards with a tiny screwdriver, or even try a different Jamma plug. These things wear out over time when changing between PCBs a lot, so sooner or later you will have to replace it, anyway.
To find out whether it´s loose chips on the board, try changing the position while it´s running, let it run in standin, lying, or various in-between positions. If behaviour changes, you have some form of loose contacts, either at the harness or on the board itself.
If it doesn´t change behaviour, you might try adjusting the voltage very slightly. Keep a voltmeter ready to check how much the game is actually drawing from your PSU. Often you need to reset the game to have an effect.
Have you cleaned the rest of the PCB, not only the contacts? Sometimes dust or humidty can cause shorts. I´d also try looking for damaged lines, but these are sometimes very hard to spot. Maybe there are wires attached to the PCB? That means someone else had problems with it before and repaired it with these wires. In that case, I´d check the wire contacts first. Don´t remove them, just bend them a little and see whether the solder moves. If it does, you need to resolder them carefully. Be careful it doesn´t come off, and remember where the wire is attached (by counting pins or whatever) in case it does.
Try to be patient, this kind of problems isn´t exactly rare, and sometimes it takes a while to figure it out, but it doesn´t help to freak out. You could ask the seller if he had problems and ask for advice. If you don´t know what to do, don´t do anything. Think about the problem for a few days, ask around, but stay calm. Chances are high the board is ok, but you might ruin it by impatient repair attempts.
As for fixing it - if the graphics looked ok for a bit while flexing it, the chances are that you have a cracked solder join somewhere. Sometimes it's down to cracked tracks or hole plates (where a track moves from topside to bottomside - these are virtually impossible to find) - but the most usual case with modern boards is where a surface mount chip leg has broken free from the board.
You'll need a very delicate and steady hand to test this. Get a craft knife, or anything else light and very very thin. Test each leg of the surface mount chips, by pushing it sideways VERY CAREFULLY. If it shows any sign whatsoever of movement, stop. If the solder is broken it will move easily, so don't use any real pressure. If you find one that does move, the solder will need to be reflowed. This just means getting a soldering iron, and reheating the leg, briefly, so that the residual solder rebonds - you don't want to try adding solder because there's a high risk of joining two legs, which is a real pain to fix.
As a sanity check though, before you do this - there are some simple checks nobody has mentioned. Check underneath the board - are any legs bent over and touching eachother? Do any legs look like there's no solder around them?
Much obliged for all the help guys. Raiden, the board is a tight fit in the harness so I think I've ruled it out. There aren't any signs of tampering either Seeing as how I've gotten it to work perfectly by flexing the pcb just right, I think it has to be a loose chip or connection but it seems impossible to tell which one is the problem.
Bloodflowers, the seller is named Aford13, a guy in the UK. In his defense, he said in the listing that all of the boards had been unchecked since November, and the other board he sold me(Batrider) worked perfectly so I don't think he was trying to roll me. You might ask what version a game is if you buy from him though, I assumed Batrider would be the japanese one but it was a korean board(with the in-game codes disabled)
The soldering on the bottom looks pretty good to me and there aren't any obvious problems that my untrained eye can spot. I'll look into checking the chip legs.
