Pacman Problems

Cpen5311

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Hey there,

New to the forum, but had to join because of some problems i am having. Hope someone can help!!

I just bought a Pacman upright and i am trying to restore it. Ran into a big problem though. When i turn it on the lights come on and so does the monitor. The monitor is just purple and there is no sound. I replaced the old PCB which was a Ms pac with the 4 in 1 Multipac, So its not the board. I also tested the fuses and they are good. The original power cord had the ground prong ripped off, so i have a new one coming in the mail. I doubt that would be the cause of it though. Also, today me and buddy made sure the pinouts were right.
Any help will be appreciated!
Thanks,
Corey
 
What voltages do you get at the connector? Remember those are AC voltages. It's not common, but the transformer in the bottom can go bad.\

Can you start a game and hear it play?
 
What connector? to the pcb? i tested most of those and theyre all good. As for the transformer i have not tested that. But if that was bad, wouldnt nothing work at all? And no sound at all comes out, just a hum as soon as it gets turned on but that fades to nothing after about 2-3 seconds. I read in another thread that the hum is due to bad fuses, but those are all testing good.
 
You have AC voltage coming out of the transformer to the Pac-Board. This voltage is usually 7vac and 12vac. These voltages get rectified on the game board into +5vdc and +12vdc. The +5 is necessary for the game board to work. The +12 is necessary for the sound to work.

You should have 6 fuses on the bottom. The two by themselves are main power and monitor power. The other four are for voltages to the game board and coin door.

You can check to see if you do have the +5vdc and the +12vdc by measuring the voltages on your game board at the banded side of the diodes in the pic below (which can also be used to hook up a switching power supply to the board if you think the transformer is bad):

DCpac.gif


If you have the proper voltages, then you most likely have a problem with the board. Check the daughter cards to make sure they are plugged in with the correct polarity and are seated properly. Pull each socketed chip, clean the legs, and reseat them.

Try wiggling the edge connector while it is on. Sometimes the pins inside the connector get dirty or bent in and they don't make good contact, causing a board to not boot properly...
 
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Ok i will test the voltage tomorrow and give you the update. You dont think anything with that ground would have anything to do with it, do you?
 
A missing ground prong may show up as some electrical interference on the screen or something, but wouldn't keep the game from running...
 
Ok, i tested the transformers. the one closest to me (the opening of the cab) was about .09 - .11. The other i could not get a steady reading, it jumped from about 1.53 to .01. For a few seconds it would stay at about .02 or .03. This leads me to think they are bad.
Then due to my knowledge of electricity (which is nothing what so ever) i thought maybe if i turned it on and test it, it would work due to the flow of voltage? well.... when i tried to test them when the machine was on, Sparks! and then no voltage.

So, on that note... Does anyone know where i can purchase Pacman transformers?:)
 
How were you trying to measure it at the transformer? If you were trying to measure DC voltage there, it's not surprising to get weird readings, as it's only AC voltage there. You need to do your voltage readings (DC) on the game board. And if you were measuring AC voltage, you won't get correct readings if you weren't measuring the proper taps.

And if you had sparks and now it's dead, then either your fuse is blown or your circuit breaker tripped....
 
Yeah i tested the board in DC and its fine. Not surprising because it is new. Like i said before, it came with a ms pacman board and then after i put in a new multipac board its still doing the same thing. So im 100% sure its not the board. I also tested the transformers in AC and after it sparked i turned it off and tested again and still got the same thing, so there not dead. That is..if theyre not dead already, which i think they are.
And does the transformer power EVERYTHING? or just the board? because the lights do come on and so does the monitor.
 
Im using this? lol

And where exactly did you have the leads plugged in when you tested the transformer?

If you got sparks out of either transformer, you have tested it incorrectly.

1 is the isolation transformer and powers the monitor, the other powers the game board and coin door.
 
Yeah i tested the board in DC and its fine. Not surprising because it is new. Like i said before, it came with a ms pacman board and then after i put in a new multipac board its still doing the same thing. So im 100% sure its not the board. I also tested the transformers in AC and after it sparked i turned it off and tested again and still got the same thing, so there not dead. That is..if theyre not dead already, which i think they are.
And does the transformer power EVERYTHING? or just the board? because the lights do come on and so does the monitor.

If you measured good DC voltage on the board, then the transformer is working fine.

There are two transformers in the bottom - one powers the board and coin door lights, the other powers the monitor (isolation transformer).

If you have good DC voltage of +5 and +12 on the board, and good ground, then you have an issue on the board if it won't play blind. Check to make sure all the socketed chips are facing the same way as the non-socketed chips, no chip legs are bent, and that the daughterboards are seated firmly. Sometimes those sockets for the daughterboards get hogged out. You can try wiggling them while watching the screen to see if anything comes up.

And if you are using a Ms. pac daughterboard with the ribbon cable, make sure a pin didn't break off the ribbon cable connector (happens a lot)...
 
And if the Transformer for the monitor is dead, would the monitor turn on at all? or just not work properly?

The isolation transformer has two wires in the bottom and two wires out the top. You should measure 120vac (approx) across the two bottom wires, and the same across the two top wires. If you do and your monitor still doesn't power up, then something is wrong with your monitor. It's possible the sparks you caused made one of the monitor fuses to blow...
 
Well the monitor still comes on and is still purple, so i didnt blow anything. And dont forget i dont get sound either, so it cant just be a bad monitor.
 
Yeah i have, and it just changed the color. Even so, there would still be the sound issue. I think im just going to buy new wiring harness and power supply i found on ebay. Also a little later on a new monitor due to this one having burn in's anyway. ...And if it still wont work, well then im just not supposed to have a Pacman machine
 
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