Ms. Pacman - getting power, screen flashes once, hums

jeffo

New member
Joined
Nov 14, 2016
Messages
10
Reaction score
0
Location
bryan, Texas
Ms. Pacman - getting power, screen flashes once, hums

Howdy
I've picked up a Ms. PacMan cabinet that I can't get to boot up.

When I plug it in and have both power switches engaged, I can hear the machine sort of hum to life, but I get no lights and nothing much else happens. The monitor does flash for a split second, sometimes with a barely visible image of the maze, sometimes just a flash of white. This only happens when I turn the machine ON.

I have checked all the fuses (6 total) on the bottom - they are good (I had to replace the top 1a fuse).

I get no lights either in the marquee or the coin slots...I have not checked if these bulbs are bad.

I have also tried booting with the monitor and the marquee disconnected - same 'alive' hum but no game sounds.

Any idea what to check next? I have a voltmeter and know how to use it.

Thank yall
 
i would start with checking all voltages thoughout the cabinet and also the +5vdc at the game pcb. some pictures of what models of monitor, etc. would be good.
 
those old fuse holders are made of galvanized steel and they rust or corrode very bad. you'll thus lose power across them, which is dangerous for the game board that takes AC voltages in and rectifies them. this is how edge connectors get burned up.

I get replacement fuse blocks from Marcos Specialties. even the mounting holes are the same. if you go through with changing the block out, make sure you only do a wire at a time, and in the exact order you take them off the old one. the wires may be a little difficult to get solder to stick to, I think Ken Layton recommends rubbing alcohol and scotch brite on the copper wiring to clean them up.

a picture of the whole monitor will be helpful. if you verify that it's got issues you might be better off making a repair thread in the monitor section.
 
those old fuse holders are made of galvanized steel and they rust or corrode very bad.

Actually they are brass. The reason they fail is brass tends to loose its spring and cracks very easily.

Have you tried coining up the machine to see if it will play blind?
 
Good news - it's alive.

I'm going to attach a couple pictures maybe yall can help explain to me what is happening.

It appears to have been an issue with the edge connector.

There are two wires that are tied together, coming from either side of what looks to me like pin 3 of the main PCB (see first pic). While I was probing the pins for power, I noticed if I slid my voltmeter far enough up into the header, it would start buzzing. I set my phone up on the other side to record what was happening, and lo and behold, the game was booting (with a very loud hum - I had the volume cranked all the way up).

So I might be a little crazy/stupid, but I figured the wires were 7v and wouldnt hurt jamming them up into the connector at the 7v spot, so I did that, minor sparks, and the game came to life (see picture 2 for an idea on how I jammed that up in there). The game runs without those wires jammed in the connector btw...just needed the boost.

I was half expecting there to be sounds right when the game turned on, but I see now that is not the case - the sounds only start once you start the game.

I'm guessing this is some sort of creative wiring fix, and I'd like to fix it properly. I've also got this hum that changes volume along with the whole game volume, so I'll try to address that too (although I'm not sure how much hum is normal - it seems unnecessarily loud to me, but I also didn't realise how loud you can crank this thing).

This is my first project like this and thank yall for the quick and helpful replies.
 

Attachments

  • IMG_2386.jpg
    IMG_2386.jpg
    204.6 KB · Views: 32
  • IMG_2387.jpg
    IMG_2387.jpg
    197.6 KB · Views: 34
The hum is likely caused by the edge connector. Fix that and you might kill two birds with one stone.

Thank you - that is encouraging. What does 'fixing' the edge connector look like?

Is it buying a new harness and putting all the wire back in? What is a good technique for cleaning up / repairing the edge connector itself? I know I can use a pencil eraser to clean the contacts, maybe some circuit board cleaner - can I re-solder the contacts or anything?

I should also mention - the filter board had been removed, but I still have it. I was thinking it might be worth to try running with the filter board - see if it cuts down any noise or if somehow the connections between the pieces at those points are better than harness directly to pcb. Does that sound worthwhile?
 
Last edited:
does this mean the harness lost its spring tension?

I'm not entirely sure what you mean - but are you talking about the contacts inside the harness? I know on an old NES 72-pin connector it's possible to kind of bend the pins back into shape. I could try that.
 
the best way is to buy a new edge connector and cut the wires on by one and install them into the new connector. it is the way that you will have the least amount of problems in the long run
 
the best way is to buy a new edge connector and cut the wires on by one and install them into the new connector. it is the way that you will have the least amount of problems in the long run

Thanks again - this is probably what I'll do. Is it worth trying to repair the contacts on the PCB as well? If so, how is this usually done?

edit: Found some really great videos on this:
https://www.youtube.com/watch?v=4qbN1uw1hlA
https://www.youtube.com/watch?v=gJsWGm7fOIQ

I'm assuming he's using something like the PacMend kit from TwoBits, even though that does look to use a different sort of connector in the end.

If anyone has any other suggestions on where to find these parts, I'm curious. I can find the edge connectors themselves for about $5 but not sure where to find other pcb repair options.
 
Last edited:
Wondering if it's ok to use these two connectors or if I'm missing something...
 

Attachments

  • EZM22DREH.jpg
    EZM22DREH.jpg
    105.7 KB · Views: 10
  • EBC-44F.jpg
    EBC-44F.jpg
    78.1 KB · Views: 10
Just a quick follow up...
I rebuilt the edge connector using the first connector in my last post. You solder the wires directly to the connector instead of inserting them in like the original.

It fixed 99% of my issues. Well, when I booted her up, she started normal, but the screen was filled with gibberish. I had seen that before and was unclear how I had fixed - always seemed like jiggling the edge was enough. Anyway that wasnt working. Finally I got my friend to watch and I started pulling out the board with the game on. Something wiggled into place and she boot up with the normal game.

No more sound buzzing issues, no more problems booting, no more garbled glitchy screen.

The only issue I still have is that the sprites all have faint horizontal lines in them. Closest I can figure from the various threads is that this could be a loose socket. If anybody knows for sure what would cause this, please let me know.

Thanks again for all yalls help.
 
I had one that was acting really funny. When it booted among other things Pacman was red. Finally traced it down to some of the IC legs right on the edge of the board around 3,4,5 A had been bent over and smashed against the board shorting to some traces going by.
 
...and go figure, I left her on one night just to have some life flow through her, and now turning her on gets no picture or sound or anything other than the operational hum.

I will start with checking fuses.
 
Back
Top Bottom