Graphical glitch help please!

[flashbackx]

So I took a gamble on this MVS cart thinking it needed a simple cleaning to fix.... and I was dead wrong. All the pins have been thoroughly cleaned, but these glitched lines surround any sprite in motion during gameplay (sorry for potato pics):





Anyone have any ideas with this?

 

[Tyranix95]

First clear your back up ram (in the test menu).

Next, if you have uni-bios on the board, then Check-sum the roms. Look for bad ones.

Then, start looking at the CHA board. Check the traces to the LS chips, then to the Mask Roms. Keep an eye out for cold solder joints on the way.

After that, use a programmer: Check the LS chips on the CHA board. Make sure they're good.

That should keep you busy.

http://www.mvs-scans.com/index.php/Nam_1975

 

[Xian Xi]

Most likely a bad trace, bad rom, cold solder joint. The Data lines go straight to the cart edge and it isn't an addressing problem so it isn't the 273s.

 

[flashbackx]

Thanks for the reply. Well, the ROM region came back as OK in the CRC check but the others were not used.

I just noticed that there is corrosion where the pin meets the chip on the CHA board:




I know it's impossible to tell by this pic but it's on the 5th and 6th pins from the top right. Also, something seems shitty about the solder on the 10th pin from the top right. Funny, because outside of that both boards appear immaculate. As for the rest of your advice, I am a greenhorn in terms of hardware w/ the Neo-Geo, so that may be a little out of my league at this point. I appreciate the advice.

 

[shadowkn55]

If you're in my area again, I'll take a look at it.

 

[Tyranix95]

Use either rubbing alcohol or contact cleaner and a toothbrush to clean the corrosion off. If its way hard, get a jeweler's screwdriver (little tiny one) and poke at it a bit.

As for the suspect cold solder joint, get your hot iron and put a dab of fresh solder on it. Make sure it's nice and clean.

XX and shadowkn55 can fix NEO carts if you get way lost. Or, if you can find your way to a local neo meet, I'm sure there will be someone there who can check it out for ya.

 

[flashbackx]

I appreciate it all. Removing the corrosion and hitting that point with the gun didn't help unfortunately. I'm probably missing something else wrong with the board as well. Gonna PM shadowkn55 and see if he can have a look; he's only a town over.

 

[BIG BEAR]

It looks like there may be corrosion on your PROG board. Examine the chips on that board and look for any greenish residue on the legs of the chips.On those particular early double layer PCBS,I've seen residue/corrosion hidden under the chips/roms.
BB

 

[flashbackx]

Thanks BB; I gave it to shadow today to have a look.

 

[shadowkn55]

Thanks BB; I gave it to shadow today to have a look.

I just checked out the data lines. Everything is connected properly. Don't see anything out of the ordinary so far.

 

[shadowkn55]

This one was a little tricky. It turned out to be a bad c2 rom. Finding out which exact rom was tricky but this game uses doubled sided solder points and desoldering every c rom would have been a huge pain in my side. I resorted to examining the sprite data in a tile editor and see if I could see any sprite tiles that matched the corrupted tiles up above. I narrowed it down to c1/c2 and I took a stab at desoldering c2 first. Turned out to be a lucky guess and my eprom reader showed a stuck data line on the rom. Burned an eprom with the proper c2 data and the game is good to go.

 

[Tyranix95]

Cool!

An'd it's the rom in the pic.

Now ain't dat fwnne.

 

[flashbackx]

This one was a little tricky. It turned out to be a bad c2 rom. Finding out which exact rom was tricky but this game uses doubled sided solder points and desoldering every c rom would have been a huge pain in my side. I resorted to examining the sprite data in a tile editor and see if I could see any sprite tiles that matched the corrupted tiles up above. I narrowed it down to c1/c2 and I took a stab at desoldering c2 first. Turned out to be a lucky guess and my eprom reader showed a stuck data line on the rom. Burned an eprom with the proper c2 data and the game is good to go.

Awesome news. Shadow, you kick ass! Thank you!

 

[Xian Xi]

So it was the corroded pin?

 

[shadowkn55]

So it was the corroded pin?

There wasn't any corrosion on the board or the rom itself. The markings the OP mentioned were scratches on the legs.

 

[flashbackx]

That's because I scratched it off with a screwdriver; it wouldn't come off with alcohol or toothbrush.....whoooops

 

[mikejmoffitt]

Wow, it's rare a mask ROM goes bad. Now that it's desoldered, how does it read when you dump it?

 

[Xian Xi]

Wow, it's rare a mask ROM goes bad. Now that it's desoldered, how does it read when you dump it?

I see it all the time but most common with the Toshiba mask roms, once in a great while the Fujitsus but so far never the Sharp ones.

 

[shadowkn55]

Wow, it's rare a mask ROM goes bad. Now that it's desoldered, how does it read when you dump it?

If I choose to ignore the error the reader gives me, it reads just fine. If you view the dump in a hex editor, it looks nearly identical to a good dump except for a stuck bit every word.

I see it all the time but most common with the Toshiba mask roms, once in a great while the Fujitsus but so far never the Sharp ones.

I believe this mask rom was a fujitsu one. The part number starts with MB which is common among fujitsu parts.