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While usually I would suspect ROMs (failed, or dirty pins) or the rom accessing(dirty socket, bad trace), since this is the CPS1 my first guess is the custom PPU chips are bad. Could be the one on the main a-board, or the one on the c-board. I've got too many broken examples of both, some of which exhibit problems like yours. Especially missing layers.
These chips are really a pain in the ass.
For debugging purposes, try switching out the a-board. If everything is hunky dory, there you go. If not, try to switch the c-board. Not so easy - they are specific to games and only occasionally interchangable. After that it can only be the b-board and then you go rom checking
These chips are really a pain in the ass.
For debugging purposes, try switching out the a-board. If everything is hunky dory, there you go. If not, try to switch the c-board. Not so easy - they are specific to games and only occasionally interchangable. After that it can only be the b-board and then you go rom checking
Damn, that is exactly what I did not want to hear (read?). Unfortunately, i do not have another of these boards, and they are impossible to get around here where I live. This one came from ebay as untested, which obviously means "I did tested it but it is so badly broken, I'd rather sell it as untested".
If anybody else has any other ideas, I'd appreciate them.
Thanks!!
If anybody else has any other ideas, I'd appreciate them.
Thanks!!
unlikely to be custom chip, otherwise the whole game would be screwed.
also not loose custom chip otherwise the fault would be more random pieces missing/corrupt.
you have lines missing. its rom or ram.
first pull the eproms, clean and replace
if the problem is still there read all the eproms/mask roms and compare with MAME crc32.
if you find a rom that doesnt match MAME get a new EPROM and program the data from MAME. that should fix your problem
if all ROMs are good, you need to replace the faulty RAM on the A Board. depending on the board you have it'll be DIP or ZIP. it's common stuff, you can buy it on ebay etc.
exactly which one is bad I cant help with. just start changing them one by one and you'll eventually fix it.
also not loose custom chip otherwise the fault would be more random pieces missing/corrupt.
you have lines missing. its rom or ram.
first pull the eproms, clean and replace
if the problem is still there read all the eproms/mask roms and compare with MAME crc32.
if you find a rom that doesnt match MAME get a new EPROM and program the data from MAME. that should fix your problem
if all ROMs are good, you need to replace the faulty RAM on the A Board. depending on the board you have it'll be DIP or ZIP. it's common stuff, you can buy it on ebay etc.
exactly which one is bad I cant help with. just start changing them one by one and you'll eventually fix it.
Hi
Thanks for the help, Mr T Guru. I tested all eproms and masked roms. All tested fine except for one (43) which had one bit different with the MAME set. I re-burned the eprom, but it seems that only controlled the region of the game, because now the warning on the start does not say that the game is for usage only in the US. Problem persists the same. Can you please guide me on which chips should I check/replace? I am not really sure which ones are the RAM.
Thanks!!
Thanks for the help, Mr T Guru. I tested all eproms and masked roms. All tested fine except for one (43) which had one bit different with the MAME set. I re-burned the eprom, but it seems that only controlled the region of the game, because now the warning on the start does not say that the game is for usage only in the US. Problem persists the same. Can you please guide me on which chips should I check/replace? I am not really sure which ones are the RAM.
Thanks!!
the PROGRAM eproms will always be different unless you pick the same region. if the graphics roms match then the roms are ok
is your version (program roms) in MAME? if not please send them to me so they can be added.
video ram is on the A board. look for a bunch of chips all together looking the same on the top right side.
unfortunately for you, not knowing what is ram also means not knowing how to remove them and not having the correct equipment.
you probably wont be able to fix it yourself.
is your version (program roms) in MAME? if not please send them to me so they can be added.
video ram is on the A board. look for a bunch of chips all together looking the same on the top right side.
unfortunately for you, not knowing what is ram also means not knowing how to remove them and not having the correct equipment.
you probably wont be able to fix it yourself.
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Thanks for the help. I will look into MAME and see if the ROM from my board is already there or not, but I suspect it is. Also, you are correct that I need help identifying the RAM chips, but I can solder and know how to replace a through-hole component. I've done many repairs to neo-geo carts before by replacing chips with eproms, so I'm comfortable with that. Only thing is that I am not very knowledgeable yet in the CPS1, so I will need a little guidance.
I'll check the traces that go to/come from the chips you mentioned and update this thread.
BTW: my board looks exactly like the one you posted on the right, the chips have a single line of pins (SIP?) as opposed to the other one which has DIPs.
Thanks!!
those rams are called ZIP
Neogeo carts are only 2 layer boards so they are easy to work on. I can remove a rom on those carts in about 20 seconds.
CPS1 (and most others) and 4 or 6 layer boards. You need proper equipment or you won't be able to remove the chip.
A hand solder-sucker won't cut it.
You need a professional desoldering gun and you'll probably need to pre-heat the board too with a hot air gun.
otherwise you can cut the chip out with fine cutters by chopping the legs as close to the plastic body as possible then heat the individual legs with a soldering iron and pull out the legs with tweezers. then suck the holes clean and replace the chip with a new one. this is a general technique applying to any chip on any board....
Neogeo carts are only 2 layer boards so they are easy to work on. I can remove a rom on those carts in about 20 seconds.
CPS1 (and most others) and 4 or 6 layer boards. You need proper equipment or you won't be able to remove the chip.
A hand solder-sucker won't cut it.
You need a professional desoldering gun and you'll probably need to pre-heat the board too with a hot air gun.
otherwise you can cut the chip out with fine cutters by chopping the legs as close to the plastic body as possible then heat the individual legs with a soldering iron and pull out the legs with tweezers. then suck the holes clean and replace the chip with a new one. this is a general technique applying to any chip on any board....
Thanks for the info, I had no idea these boards had that many layers. In fact, I think I will do the cutting legs technique you mentioned, since I do not have anything close to professional to do the desoldering. not even a hot air gun.
Thanks!!
the ram is common just order a full set and replace everything.
if you want an easy repair next time it happens (it will) fit machine pins to the holes so you can remove the rams easily.
you cant buy zip sockets nowadays but you can make them from individual pins from strips.
insert the pins into the holes, push the ram in so everything lines up properly then solder it underneath.
if you want an easy repair next time it happens (it will) fit machine pins to the holes so you can remove the rams easily.
you cant buy zip sockets nowadays but you can make them from individual pins from strips.
insert the pins into the holes, push the ram in so everything lines up properly then solder it underneath.
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Good stuff, you're probably right about the RAM, just when he said 'layers' were missing I instantly thought the custom chips. If it's just strips of data then yeah more likely ROMs or RAM.
Good tips for the RAM replacement btw. If I had more boards with working PPUs I'd be fixing them up :/
Good tips for the RAM replacement btw. If I had more boards with working PPUs I'd be fixing them up :/
Hi
Sorry for late reply, have had no time to check into this yet, however I would like to know if there is any difference between the DIP and ZIP form factor in the RAM chips. My board currently has ZIP chips, but I'll give a shot at replacing them, can I just get DIP chips and solder them in? or should I do any other changes?
Thanks!!
Sorry for late reply, have had no time to check into this yet, however I would like to know if there is any difference between the DIP and ZIP form factor in the RAM chips. My board currently has ZIP chips, but I'll give a shot at replacing them, can I just get DIP chips and solder them in? or should I do any other changes?
Thanks!!
