Contra PCB works but there are no players

Shawn1976

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Ok.
I've got a Konami Contra PCB. The problem that I'm having is when I power up the board the rom test shows that all of the roms are "OK".
From there the Contra Demo Screen pops up with the music being perfect.
The problem is when the demo begins showing the game play there are no players or enemies shown on the screen.
Can someone give me some direction as to what problem I'm having?
Any help would be greatly appreciated.
Thanks in advance.
 

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The parts that move are called the sprites, that's what's missing. It could be a bunch of things, but usually people point to the ram possibly being messed up.

First though, and I know it's a pain, get the board out of the game, and look really carefully at every single trace on it. If there's a cut somewhere you could lose all the sprites like this. It's really easy for a game to get scratched sitting on a shelf, or with another board rubbing against it... and if 1 trace gets cut it'll cause issues like this. Look really close for damage anywhere.
 
Ok.
I've got a Konami Contra PCB. The problem that I'm having is when I power up the board the rom test shows that all of the roms are "OK".
From there the Contra Demo Screen pops up with the music being perfect.
The problem is when the demo begins showing the game play there are no players or enemies shown on the screen.
Can someone give me some direction as to what problem I'm having?
Any help would be greatly appreciated.
Thanks in advance.

What happens if you try to play a game?

Do you hear the correct sounds; if yes Roms etc are probably good and you most likely have a video ram problem. If not you can have a rom problem (Not actual chip but a supporting chip), or even a prom.
 
The game plays and sounds fine, you just can't see anything other than the background.
No characters at all.
 
And I checked the back of the board as well as the jamma connection and I don't see any broken traces.

It is most probable a ram issue, either voltage low on the ram chip(s) or a connection to the ram chip(s).

Ram chip(s) can and do go bad.
 
Is there someone I can send it to, to repair/replace whatever needs fixing?

There is someone close to you that can do that for you but I can't remember his name or call sign.

You can pm Riptor, if he doesn't work on them he can tell you who can.
 
And I checked the back of the board as well as the jamma connection and I don't see any broken traces.

The suggestion was posted at 6:21 (PDT) and you posted your response at 6:27. There is NO WAY in hell that a visual inspection (worth a damn) was done in 6 minutes. I think the suggestion to carefully and fully inspect for physical damage is a worthwhile one; and it'll probably take a good 20mins more more (I've spent over an hour on occation) with a magnifier, to do a decent job checking for possible damage.

The suggestion to verify you voltage is also a good one.

If you haven't already, re-seat your EPROMs, esp the gfx EPROMs (7D 7F 16D 16F). I'd pull them and verify their data, but IIRC you don't have the equipment to do that.

After that, try lightly tapping the two bigass chips on the board (they're gfx chips) and very lightly flexing the PCB, while watching the game to see if the sprites flicker. You're checking for a bad connection with those bigass gfx chips.
 
The suggestion was posted at 6:21 (PDT) and you posted your response at 6:27. There is NO WAY in hell that a visual inspection (worth a damn) was done in 6 minutes. I think the suggestion to carefully and fully inspect for physical damage is a worthwhile one; and it'll probably take a good 20mins more more (I've spent over an hour on occation) with a magnifier, to do a decent job checking for possible damage.

The suggestion to verify you voltage is also a good one.

If you haven't already, re-seat your EPROMs, esp the gfx EPROMs (7D 7F 16D 16F). I'd pull them and verify their data, but IIRC you don't have the equipment to do that.

After that, try lightly tapping the two bigass chips on the board (they're gfx chips) and very lightly flexing the PCB, while watching the game to see if the sprites flicker. You're checking for a bad connection with those bigass gfx chips.

And he is in FL also!
 
The suggestion was posted at 6:21 (PDT) and you posted your response at 6:27. There is NO WAY in hell that a visual inspection (worth a damn) was done in 6 minutes. I think the suggestion to carefully and fully inspect for physical damage is a worthwhile one; and it'll probably take a good 20mins more more (I've spent over an hour on occation) with a magnifier, to do a decent job checking for possible damage.

+1 to that. I inspected an Aero Fighters pcb twice and had started piggybacking TTL chips in the graphics circuit for some scrambled sprites and static on the audio. It was on the third careful inspection that I found the gouge on the top of the board near the sound ROM that had cut three traces. It was tiny and I had thought it was a paint mark the previous times. Jumpered them back together and the board now works great.

You have to go SSLLOOWW and do it under daylight or 100 watt bulbs at least.

Good luck,
Brian.
 
Well I tried tapping the big Konami chips towards the bottom left portion of the PCB as well as sligtly flexing the board but I didn't have any luck with that.
I did already try to re-seat all of the EPROMs prior and obviously still have the same results.
As for the equipment to verify the data, you are correct and I do not have the equipment to do so.
Being I'm in St. Augustine would I be able to bring the board to you to take a look at?

The suggestion was posted at 6:21 (PDT) and you posted your response at 6:27. There is NO WAY in hell that a visual inspection (worth a damn) was done in 6 minutes. I think the suggestion to carefully and fully inspect for physical damage is a worthwhile one; and it'll probably take a good 20mins more more (I've spent over an hour on occation) with a magnifier, to do a decent job checking for possible damage.

The suggestion to verify you voltage is also a good one.

If you haven't already, re-seat your EPROMs, esp the gfx EPROMs (7D 7F 16D 16F). I'd pull them and verify their data, but IIRC you don't have the equipment to do that.

After that, try lightly tapping the two bigass chips on the board (they're gfx chips) and very lightly flexing the PCB, while watching the game to see if the sprites flicker. You're checking for a bad connection with those bigass gfx chips.
 
Turns out it looking like it was a ram issue.
We'll see here in the next week or so.
Thanks again Riptor for helping me out.
 
The board is fixed. It was not just one bad ram, all 4 character sprite rams were bad. Two are for the main characters and the other two are for the enemy characters. Strange that all of them went out, I guess one took the rest with it.
 
The board is fixed. It was not just one bad ram, all 4 character sprite rams were bad. Two are for the main characters and the other two are for the enemy characters. Strange that all of them went out, I guess one took the rest with it.

Glad it is working!
 
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