Help with a Pacman board issue

[2PacMan]

I bought a Pacman Plus game the other day, got it home, plugged it in, and this came up (pic 1).  I put the board in my other working pacman cab and got the same thing, so I know it's not a monitor issue, it's def. a board issue.  Does anyone know what it could be?  I checked the Pacman troubleshooting page where they have all the pictures, but my particular problem is not on there.  I noticed my original pacman board had two 'piggybacked' boards, where this one only has one.  And in the pacman plus manual, it shows some kind of board attatched by a ribbon cable, which mine does not have.  As you can see by the pics, this board had been messed with before, there are jumpers on the back and the edge connector has been resoldered as it looks like it got burnt at one time.  I reseated and cleaned all the chips and there was no improvement.  Any help would be greatly appreciated, thanks.

[Level42]

This looks to me like a sync issue. Maybe the sync signals are inverted or exchanged ?

[2PacMan]

Looks like that could be it....how do I fix it?

[grantspain]

can you see the picture changing through the fuzz?

[Q*Bert_OP]

try putting regular pac roms on it...it cant be a legit pacman plus w/out the "epoxy" daughter board...

[modessitt]

We need more arcade techs on here!  (Grant!  Shame on you for not mentioning the most likely problem!  Although to be fair, you're still gathering info...  )

It's obvious by the narrow picture that the vertical width isn't adjusted properly, but your main problem seems to be the holds, either Horizontal or Vertical (or both).  Even if you're missing the extra board and this isn't a hack version not using it, you should still get a stable picture of garbage...

Since you haven't mentioned what type of monitor this is, you'll have to find the hold adjustment pots on the monitor chassis and adjust them until the picture locks.  Vertical lines seem to indicate the horizontal hold should be adjusted first, but you may need to do both.  If the sync is messed up (should be negative sync) then this won't work.  And of course, if it slows down so you can see it, but can't quite get it to lock, then it's time for a cap kit on the monitor.

Once you have a stable picture, then you can adjust the vertical width pot to get it to fill the screen.  If you still have problems, post this over in Monitor/Video for more help.  Once your picture is good, then you can find out if the game is working, although you should be able to add credits and hit the start button to see if you hear sounds (if the volume is up).

[2PacMan]

It's not the monitor I don't think.  I have a working pacman, plugged this board in and it does the same thing.  Unless i'd have to adjust the monitor for a different board, is that possible? 

I noticed too that it's missing the pacman plus auxillary board.  I don't have one, but shouldn't it still work without it?  Just with garbled graphics or something?  I don't have any original pacman roms to test this with. 

The lines are just a stationary picture, nothing is changing at all, the game won't coin up or anything, and there is no sound.

[RayB]

It's not the monitor I don't think.  I have a working pacman, plugged this board in and it does the same thing.  Unless i'd have to adjust the monitor for a different board, is that possible? 

It's possible.

[2PacMan]

OK, well, it's a start...i'll try to fiddle with the monitor a bit this evening.  I can't get any sound or coin up, but if I can get a better picture, maybe i can figure out what's going on...i wish i could get it into the self test, but i can't get that far.

[SirPeale]

It's not the monitor I don't think.  I have a working pacman, plugged this board in and it does the same thing.  Unless i'd have to adjust the monitor for a different board, is that possible? 

You're telling me, that with such a simple possible solution, you didn't even try?

edit: didn't get to this part:

I can't get any sound or coin up, but if I can get a better picture, maybe i can figure out what's going on...i wish i could get it into the self test, but i can't get that far.

Still try adjusting the monitor, but yes, it sounds like you have some board issue of unknown type.

[2PacMan]

Yeah, i'm 99% sure it's a board issue.  Could putting the edge connector on backwards have anything to do with this?  I looked a my working pacman and put the connector on the same way, but could i reverse it? 

[grantspain]

not a good idea to reverse edge connectors,untold grief can be caused-maybe you have blown a few video rams

[Witchboard]

First things first.  You need to get a complete board set.  Are you sure this is a Pac-Man Plus?  The satellite boards plug into where the CPU goes.  Yours already has a CPU installed and not an empty socket like the satellite board was removed.

Also, I can't tell if you have a chip installed where the sync bus controller goes, but if not, you need to get one.  Once you have all the parts, then you can start troubleshooting.  Who knows how the board will function without all the parts.

If you still get the same thing after all the parts are present, I would look at chips 2R & 2S.  Your screen looks similar to the picture on this troubleshooting site.

[modessitt]

I have a working pacman, plugged this board in and it does the same thing. 

You plugged this board into your pac-man cabinet and it didn't work.  Try plugging your pac-man board into this cabinet.  That will tell you if the monitor is working properly.....

[2PacMan]

Thanks for all the replies guys. 

Witchboard, where is the sync bus chip supposed to be located?  When i bought the cabinet, it had the "PacMan Plus" marquee on it, and inside there was a manual for the conversion to the pacman plus kit.  But the board has some jumpers on the back like it was hacked someway.  And you're right, the pac plus aux board is missing, but it's got a chip there in it's place.  There were about 7 or 8 chips laying in the bottom of the cabinet which i assume were the original pacman roms, but they aren't labelled or anything, so i have no idea where they go.

[Dav]

Every pac I've seen with 6 chips in row 6 has been converted to a bootleg ms pac so that's almost certainly what you have there.

The sync bus controller is in row 6 between the 40 pin cpu and the first 24 pin rom.  There's a 28 pin socket there.   I can't tell from your pic if you have a chip there or not.  Usually there's a small board that plugs in there but it's possible you have a chip.  You must have one or the other.

[Witchboard]

I would have to agree with Dav.  According to the PacPlus documentation, you should only have the 4 EPROMs in row 6.  This, plus the fact that the board has a trace hack indicates it's probably some kind of bootleg.

As Dav has already explained, the sync bus board should be in socket 6D (The one with the holes on each side for the zip tie), and it is required on all versions of Pac including all bootlegs I've seen.

The cool thing is, you can probably reconvert it back into a legitimate Pac game if you so choose.  The first thing would be to get a replacement  sync bus satellite board and see at the board does as is.

[2PacMan]

Thanks for the input guys.  There is a chip where the sync bus board should be, so maybe that chip went bad.  Are replacement sync bus boards expensive?  It does look like he did one of those ms pacman hacks.  I saw one on another page that involves wiring jumpers like he did.  And he scratched through a trace on the back as well.

Is there anyone that offers a service of fixing pac boards?  Like sending in a broken one and getting a working one in return?  I'd really like to have this a legitamate pacplus board.

[Level42]

mikesarcade.com offers that service, but not sure about this board...

[Dav]

Thanks for the input guys.  There is a chip where the sync bus board should be, so maybe that chip went bad.  Are replacement sync bus boards expensive?  It does look like he did one of those ms pacman hacks.  I saw one on another page that involves wiring jumpers like he did.  And he scratched through a trace on the back as well.

Is there anyone that offers a service of fixing pac boards?  Like sending in a broken one and getting a working one in return?  I'd really like to have this a legitamate pacplus board.

The early pac boards had custom chips in place of the 2 daughterboards.  Demand outstripped supply and they had to make a replacement board for it.  I used to sell sync bus controllers for $15 but contrary to what it sounds like I don't think they affect the sync.  You'd get random characters on the screen if it were bad.  If it is the board you've probably got something going on in the clock circuit.  You sometimes have to adjust the monitor a little between 2 different boards, but 2 of the same boards you shouldn't have to.

Generally I think the 6 rom hack for mspac will still run the 4 roms for pacman and pacman plus if you can get the board working. 

To get it to run pac plus again you'll need the 2 graphics roms (5e,5f), 4 row 6 roms, 2 color proms and the exoxy auxillary board.  You should be able to get them fairly cheap on ebay as most people yank them out.  You could also probably find someone to burn the 4 row 6 roms decrypted so you don't need the epoxy block but you'll still need to buy 2 color proms to get the right colors.  Assuming of course that ms pac has the right colors.  I have seen pac plus to ms pac conversions where they kept the pac plus color proms and went with pac plus style bonuses.

[Witchboard]

I think I found your Pac board hack.  Looks like it's a Ms. Pac-Man hack that doesn't use the daughter board.  That would make sense considering you don't have one and the CPU is still installed.  The trace cuts & jumper wire look similar.  You can check out the hack here.

[2PacMan]

Ah!  That looks pretty close to what my board has.  Looks like mine was hacked to play ms pac possibly.  Now, any ideas how to fix it?  I'm probably going to have to cut all the jumpers and jumper all the cut traces, buy a new sync board and revert back to a working pacman and go from there, huh?

[Witchboard]

That would be my recommendation, but it's really up to you.  It will be easier to troubleshoot as an original board, then you can look at converting it to whatever you would wish. 

There is a chip where the sync bus board should be

As Dav previously stated, they originally had custom chips at this location.  If it is a "NVC285" chip then you will not need a replacement sync board, presuming this chip is still good.