cps1 no picture, random sound.

shinobi3

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hi.

I have got a cps1 pcb, when i turn on, the picture es black, and i can hear a sound, but it is a random sound.

Can you help me ?

thanks.
 
They do that when the main CPU and/or code EPROM is missing or bad. A (working) sound CPU, however, makes the random sound on its own at power-up. Check to make sure you aren't missing some EPROMs (exactly which ones should be there depends on the game), and that the code is good.

Also, the game may or may not have suffered from the "suicide battery." You can read more about affected games, and fixes, on this page: http://www.arcadecollecting.com/dead/dead.html
 
the problem is in the 1 st floor, I guess the cpu, because I changed the other floors for another game and is the same.

Sometimes i can see this static picture.



What is the cpu chip? How I can verify if this is the fault? I have logic probe.

The game has no suicide battery.

thanks for your help.
 
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You can check the CPU functions on the solder side of the CPS mobo. It would probally
make things easier if you used your meter continuity test to locate the vias you need to test beforehand and then plug the rom board in.

I would check the adresses, data, reset, enable, clock, halt, ground, and +5V first.
 

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I'm certainly no CPS-1 expert, but I'll take a stab...

First some terminology: In CPS-1 lingo, the bottom (largest) board, is the "A" board. The middle one, loaded with EPROMs, is the "B" board. And the smallest one on top is the "C" board.

Second: would be helpful to know exactly which games you're talking about; which game has the problem, and which game's B- & C-boards you swapped in to verify that the problem is with your A-board.

The CPU on CPS-1 games is on the A-board. It's a 68000. It'll be square, and labeled with a number that includes 68000 or 68C000 or something similar.

Beyond that, someone with more knowledge will likely have to step in, as I haven't had an occation to work on an A-board yet.
 
I've been looking at basic signs quickly.

The reset signal and halt ok
the clk ok
and it appears that the data and address signals pressed.

Everything seems to work fine, but no picture on screen, but hear sound random, but funny thing happens when the sound ends, the processor signals seem to go crazy.

tomorrow I will look more closely at the signals.

The pcb is a Daimakaimura
 
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They do that when the main CPU and/or code EPROM is missing or bad. A (working) sound CPU, however, makes the random sound on its own at power-up. Check to make sure you aren't missing some EPROMs (exactly which ones should be there depends on the game), and that the code is good.

Also, the game may or may not have suffered from the "suicide battery." You can read more about affected games, and fixes, on this page: http://www.arcadecollecting.com/dead/dead.html

+1

I can't say it enough, You have to verify the programming is good BEFORE you start looking at hardware faults.
 
Not sure about the japanese version, but I think the US version only had 2 empty sockets on the B-board. Are you sure you've got all required EPROMs?

Make sure none of them are installed backwards.
Make sure none of them have bent/broken legs due to careless installation.
 


B and C board work good in another A board, the problem is A board.

thanks
 
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It had a path to a ram HM65256BLSP that was cut in an io pin.

the sound works well, the game seems to be going well, but the background is the color white, very high.

the result now is this.





I can not put into test mode, because the blue screen appears.

Thanks
 
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Like others have said check the A board RAM.

I had an older style board like that with color problems and the fault
was a bad CXK5814P-45 ram in the 2D-5D section.
 
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