Ms Pac Drama

JLS2016

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So I was moving my Ms Pac cocktail a few feet to one side so I could work on it and it got dropped maybe less then an inch from the ground. I was just trying to slightly pick it up while sliding it over as to not scrape the bottom of the cab across the floor.

It instantly did this.

I'm not sure what I could have done but it doesn't look good. Any ideas?

Thanks!
 

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also. stuff like this happens due to shoddy edge connectors... remove the edge connector and make sure all pins are cleaned nice & shiny and inspect the pins inside to make sure all is in order, for example:

bad one:

molex.jpg


good one:

maxresdefault.jpg


video of edge connector repair: https://www.youtube.com/watch?v=gJsWGm7fOIQ
 
Well, I reseated a few things like ROM's...lol. Checked the edge connectors and they looked good. But before I got to test I had unplugged a brittle 40 pin ribbon cable and broke one of the teeth off :(

I'll order a new one in the morning.

Looking forward to getting to see if any of my changes did anything. The board the ribbon was connected to was a two-bits abc diagnostic board. Go figure...lol. At least I know I got that now. Will have to research what it entails....
 
In that first pic, is that Vaseline?

no idea! you can never be sure of the photos that come out of a google image search! :)

The board the ribbon was connected to was a two-bits abc diagnostic board. Go figure...lol. At least I know I got that now. Will have to research what it entails....

yeah when I got my ms pacman, took out the pcb, that's what mine had in it too, that 2bit abc romset. the best thing to do is de-convert it back to normal pacman or ms pacman without that romset. this involves downloading the rom images and burning them to the eprom ic's.
 
Well, I reseated a few things like ROM's...lol. Checked the edge connectors and they looked good. But before I got to test I had unplugged a brittle 40 pin ribbon cable and broke one of the teeth off :(

I'll order a new one in the morning.

Looking forward to getting to see if any of my changes did anything. The board the ribbon was connected to was a two-bits abc diagnostic board. Go figure...lol. At least I know I got that now. Will have to research what it entails....

Here's a little tip for you:

While you wait for your replacement ribbon cable, you can still test your board to see if it works. The socket that the ribbon cable plugs into on your main pcb is the CPU socket. The actual game CPU is located on the daughter card at the other end of your (now broken) ribbon cable.

For testing purposes, you can (carefully!) remove that CPU and plug it into the CPU socket of the main PCB. Make sure it's plugged in oriented the correct way - look at the dots on the other chips to make sure it's plugged in correctly.

You can run your game without the daughter board - it will just be "pacman" instead of Ms Pac. (but with Ms Pac charachters).
 
You can run your game without the daughter board - it will just be "pacman" instead of Ms Pac. (but with Ms Pac charachters).
thats not exactly true... you have to verify that you have all the eproms on the main pcb

I disagree. If it's a 100% legit OEM Ms Pac setup, you can absolutely run that board without the Aux pcb. Just plug the CPU into the CPU socket and PacMan will come up. (with Ms Pac charachters, since that code is stored in eproms 5E and 5F).
 
I disagree. If it's a 100% legit OEM Ms Pac setup, you can absolutely run that board without the Aux pcb. Just plug the CPU into the CPU socket and PacMan will come up. (with Ms Pac charachters, since that code is stored in eproms 5E and 5F).

ah okay, then what i dealt with was abnormal. i had to re-burn and put in extra eproms that were missing.

i think whomever had my mspacman before me used the 2bit abc to workaround issues.
 
ah okay, then what i dealt with was abnormal. i had to re-burn and put in extra eproms that were missing.

i think whomever had my mspacman before me used the 2bit abc to workaround issues.

That's possible. The ABC diag board contains all the data found in the four roms at 6E-6J. That's why it's possible to run a board with the ABC kit installed with zero eproms installed in those spots. The ABC kit bypasses all those rom sockets, storing all the data right on the ABC daughtercard.

One of the biggest problems with these Midway pcb's is the roms sockets suck. That's why the ABC kit solves some people's issues - if any of the rom sockets 6E-6J are bad (or the roms are corrupt) the kit will still boot the board.

I'm not a big fan of the ABC kits, because they don't really fix a board - they just apply a band-aid to an other wise more serious problem. Sure the kit will boot the board in some cases, but it really doesn't provide any more diagnostics than the onboard diags do.
 
Ok, will I have to unplug the other end of the ribbon cable that's plugged into the main board? It's kind of hiding behind some mini-board thing that is plugged in and zip tied to the main board. I know it has a speed chip in it so it might be that?
 
Ok, will I have to unplug the other end of the ribbon cable that's plugged into the main board? It's kind of hiding behind some mini-board thing that is plugged in and zip tied to the main board. I know it has a speed chip in it so it might be that?

No, the speed up chip is located at 6F. Leave that alone. It has nothing to do with your issue.

The zip-tied board is the sync bus controller pcb. You will need to remove that board to replace your ribbon cable anyway, so it's OK to cut the cable tie and pull it off. Be careful with the socket and pins, as they are not as strong as most machine pins. You'll see what I mean when you remove it.

Take pictures before you take anything apart.

After you remove the sync bus controller board, you can transfer the Z80 CPU from the daughter card to the CPU socket on the main board. Then gently place the sync bus controller board back in its socket and test the board. You can tie the sync board in place with string if you like, if you're concerned about it falling out while testing the pcb. Don't use twist ties, and they have a metal thread in the core - extra metal wires near a pcb = bad.
 
Ok, will I have to unplug the other end of the ribbon cable that's plugged into the main board? It's kind of hiding behind some mini-board thing that is plugged in and zip tied to the main board. I know it has a speed chip in it so it might be that?

Also, to answer a bit more info about that board:

Back in the days of arcade manufacturing, Midway/Namco were churning out thousands of PCBs off the assembly lines. Two of the chips that the PacMan (and Ms Pac) boards used were the sync bus controller and the VRAM addresser.

See below...

Yes.

Early runs of pac boards had custom IC's instead of the cards for the Sync controller and VRAM add. The story goes (short version) that not enough of the customs could be supplied to keep up with demand, so cards using standard off the shelf IC's were created.

The custom's and cards are interchangeable.


D
 
Well, it kinda got a bit noisy when I plugged it in so I unplugged it. Re-pressed everything I touched and re-plugged. I get this...

Mind you, on the abc board it still has a thing labeled "game rom" on it. Not sure if that needed to be transferred too?
 

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Scratch that... I forgot to plug back that thing that was zip tied on the second go around. Still makes crazy sounds and this is the screen...
 

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