CPS1 vertical lines on sprites

[littlecharlie]

Hi, I've been using my SFII' board for a long time, and suddenly, now the board shows vertical lines on sprites and on other items (like the health bar).

I discard a broken trace or anything similar because I haven't manipulated the board for a long time.

Also, I have a working SFII board, and I have used its A board with my B+C SFII' boards, and the game plays just fine, so it's definitely a problem with the SFII' A board.

So, can you please point me in the right direction? Maybe a problem with the RAMs?

Also, is it possible to use a logic probe just powering the A board? It's obviously almost impracticable to probe the components in the A board with the B board on top.

 

[ShootTheCore]

Unfortunately the CPS-A custom chip has a very high failure rate and typically vertical lines through the graphics occurs when its on its way out.

You can get a replacement donor from another CPS1 A board or from a CPS2 A Board - a donor from a CPS2 will likely last longer.

There is a CPS1 Diagnostic ROM you can try that tests some of the RAM. You should also check the connectors on your A board and make sure none of the pins are bent or missing. Reflowing the solder on the CPS-A custom is a good idea too. Check for trace damage underneath the A board. Logic probe the DRAM and look for stuck lines - if you find some, trace them back to their source.

As far as logic probing the A board, you can either hit it from underneath, or buy one of these diagnostic spacer kits:

Capcom CPS1 A Board Diagnostics / Repair Tool

This tool allows you to mount a CPS1 A board (motherboard) above the B and C boards. Giving you easy access to all the IC pins and making it easier to probe and troubleshoot issues with the A board. Without resorting to blind or educated guesses as to what might be wrong. FEATURES /...

www.arcaniac.com

The A board will sit idle without the B+C board connected - not useful for diagnosing anything beyond making sure each chip has power and ground.

Take a look at this too:

Capcom CPS (CPS-1) Repair Guide – pcbjunkie.net

pcbjunkie.net

 

[littlecharlie]

Thanks for the information shootthecore.

The adaptors are awesome, but way too expensive (and just for troobleshooting one board). I'll try to buy a working A board for that price.

I'll test the Drams (which I think are the ones responsible for the sprites) from underneath and check anything suspicious (I have a working cps1 board so I'll try and compare).

Hopefully it's not the CPS-A ppu...