Strange Ms. Pacman FUSE Problem

Parpunk

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Hey guys. I put a new set of eproms in my original stand up ms pacman and whenever i went to turn it back on i couldn't get anything to come up. Come to find out the bottom 2 fuses had blown (bottom two closest to the back door of the arcade). Well i got out some of Bob Roberts circuit breaker fuse testers and put it on each one, game fired up worked perfect. The new speed up cheat chip i got from hobbyroms is awesome. (hold player 2 to speed up and player 1 button to be invincible). So anyways i figured problem solved. So i put 2 5 Amp 250 volt fuses in the bottom (this is what was in there when i first got the machine, guess thats what i need?) . Fired it up. No fuses blew i figured i was good to go.

Well after being on for about 30 seconds ill see the ghosts start flying across the screen going through mazes and over top of mazes, and then it will reset???? This is weird? What could be causing this??? I take the fuses out and hook the alligator clips back up and it works perfect 100 percent??? I even played it for about 15 minutes with the alligator clips on it.

I doubt there is a short because it never blows the fuses?? It seems like when there is a fuse in there its not getting enough volts, but something originally blew both fuses? I just bought a new power cord for it and that didn't seem to do anything either. I do notice with the alligator clips on i hear a very light hum, and it looks like its really getting a lot of juice. Any ideas?
 
Fuseholders could be bad.

Gameboard edge connector could have problems.

Filter board (if installed) could be bad.

All of above.
 
ok cool thanks for the tip.

1. How can i tell if my board has the filter thing?
2. Where can i buy fuse holders for a ms. pac?

3. Any idea why it works perfect with an alligator clip but messes up with a fuse in there? BTW i covered the fuses in aluminum foil and it still had the problems lol.

Seems like it works perfect with the alligator clips but nothing else?
 
1. The filter board will sit between the cabinet wiring harness and your game board. It has a series of resistors and diodes on it and can be removed/discarded if it is present.

2. Bob Roberts sells a kit and the standard fuse holders that Radio Shack sells will work as well.

3. The fuse is not getting a solid connection because the tension on the fuse holder is not strong enough anymore. Aligator clips bypass the tension fit and that is why you don't experience the same issues.
 
ok great thanks for the tips. I notice im getting the extremely light hum bar like symptoms i was reading about on bob's page here>

http://www.therealbobroberts.net/hum.html

seems like an extremely faint light bar scrolling across the screen. You can only really see it when looking for it but i can see it there. I'm gonna order a new fuse holder and maybe do the pcb edge thing if that doesn't fix it.

I was just so surprised that a fuse holder can cause all the characters to float around all over the screen and cause it to reset? As i said when i used the alligator clips it didnt do that at all. i hope this is all it is.

As for a filter board i don't think this machine has one. looks like the connector plugs straight into the edge of the board.

thanks everyone yet again for the advice!
 
The pcb is not getting proper voltage. I bet your edge connector ground is toast. Replace the fuse block if they are original. If the edge connector is burnt it will need repair.
 
my ps mac got a bob roberts fuse holder.. tron got a fuse holder from oreiley auto parts.. those midway fise holders suck. They lose tension then the fuses run hot and fail due to heat. Replace it, also check all the molex connectors in the cab, the square molex connector about a foot away from the pcb set tends to corrode. On mine, i cut that one out and soldered the wires togther. Also make sure you have 120vac into the cab via the power cord. Its rare but i have seen arcade games act funnly onlt to find a 10 or 20vac voltage drop fromt he wall to the cabinet due to a bad cord or cord plug.
 
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