Scrambled Shinobi Video

JonM

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I just started working on a broken Shinobi. I've got the board on my test rig using a Sega16-2-JAMMA connector, a new switcher, and a CGA-2-VGA converter board. This setup works perfectly with other boards. The Shinobi however appears to work but has corrupt video. I don't have a speaker wired up yet but I'm almost certain this board (System16 B) has a dead suicide chip. I've attached a picture of the corrupt video. I ran through the built-in memory tests and everything passed. Any ideas on what could be wrong? Any help would be appreciated. I swear I thought I saw a post with the same issue a while back. I searched for an hour before posting this.

Thanks,

Jon
 

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  • CorruptShinobi.jpg
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The suicide chip (if present) is not the cause of this fault, the two options for suicide chips on Shinobi would either kill the games ability to run at all, or just the sound depending on which of the CPUs is the suicide enabled one.

Its quite common for RAM tests on any given board to only test some of the RAM, commonly only that which is directly contactable by the CPU itself, RAM under the control of graphics subsystems is often ignored. On these boards the built in test ignores the sprite and sprite palette RAM, which as you have repeating corruption in the foreground I would say is the most likely candidate. These chips are likely to be Sony CXK5816 chips that live underneath the ROM board towards the bottom of the PCB, there are 4 in a column to the left of the square custom and two above it.

IMG_1352.jpg


You have probably lost one or more of those. If you dont have a scope and want to shotgun the repair I would start with the chip closest to the edge of the board as the gut-feel likely candidate. Edge chips tend to fail more often in my experience, probably due to staticy fingers holding the board in that area.
 
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That makes a lot of sense. Do you know a good website where I can pickup some of these chips?
 
Not off the top of my head, they are standard 6116 compatibles tho, 0.3' width.
 
You have probably lost one or more of those. If you dont have a scope and want to shotgun the repair I would start with the chip closest to the edge of the board as the gut-feel likely candidate. Edge chips tend to fail more often in my experience, probably due to staticy fingers holding the board in that area.

I have found this also and don't really know why but I would bet you are right, static discharge. Not always edge parts but quite often.
 
I just finished installing the new chips (with sockets) and it fixed the video problem! (Attached pic). Now I just need to figure out why the sound doesn't work. It doesn't seem to have a suicide chip but I'm tempted to replace the Z80B anyway. Thanks again for your help!!

Jon
 

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I spoke too soon! The video does look good, but I can't see any of the characters, just the background. If those were sprite chips I wonder if I didn't get one of them seater properly. I'm going to check all six of them. Also, I found out the sound does work on my test rig. Attract mode was turned off, as soon as I put a coin in I was almost deaf (huh?). The guy I got it from told me the sound was bad. Anyway, could the missing foreground sprite characters be a different set of chips?
 
I don't see any. I also just looked at the six chips I replaced with sockets+new chips. I don't see any bent pins. Any ideas on what chip is responsible for the character on the screen?
 
- I've retouched all of the solder joints for the sockets. No change.
- I pulled all the chips out to verify I had'nt been a pin. No bent pins. Reseated. No Change
- I pulled out all the chips and then powered on the game. It runs the same. So its like these chips are totally dead or something?
- Do I have the right chip? I ordered them from Bob Roberts, they say 2016 not 6116. (Pic atttched). I ask this because his site lists both 2016 and 6616 sram chips.
 

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MCM2016 should be fine since it's a 2k x 8 unless it has a different pinout than a 2018/6116/5814. But I do notice that the replacement are a slower speed, I wonder if that affects it. The stock ones were -35 and the new ones are -55.
 
20ns shouldn't be an issue there... If it were, the graphics would be even more garbled.

Most games use different RAMs for foreground vs. background graphics and mix them in via a different set of chips. Check for more bad RAM.

Also, check the socketed custom logic (PAL/GAL) chips in that area. Someone could've put one in backwards or mixed a couple of them up.
 
- I only see one socketed chip in the area, AMPAL16R6APC 315-5213. I removed it and replaced it making sure it was in the socket the correct way. No change. Is this a chip I can/should buy? I think I see a little AMD logo on it.

- I also tested the voltage on each of the six new chips. They are all getting exactly 4.82V.
 
- I only see one socketed chip in the area, AMPAL16R6APC 315-5213. I removed it and replaced it making sure it was in the socket the correct way. No change. Is this a chip I can/should buy? I think I see a little AMD logo on it.
You can certainly buy one, but it would need to be programmed.

JonM said:
- I also tested the voltage on each of the six new chips. They are all getting exactly 4.82V.
That's not great...
 
Got it to 5.0V. No change. I think I'm going to buy a working Shinobi and try swapping some of the socketed parts and the top board to see if I can narrow it down any further.
 
Got it to 5.0V. No change. I think I'm going to buy a working Shinobi and try swapping some of the socketed parts and the top board to see if I can narrow it down any further.

Verify ALL of the roms first. I think some of the roms are just for sprites. In any case, it would be nice to know you have a working program.
 
How do I verify ROMs? I don't have anything that can burn or verify roms.
 
How do I verify ROMs? I don't have anything that can burn or verify roms.

there should be a member near buy that has a eprom programmer that can do this for you, might cost a 12 pack, beer soda,etc. Just bring the board over and the 12 pack. Should not take more than 1 12 pack.
 
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