Pacman. What's with the 2 transformers?

Phetishboy

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If I am jammatizing a Pacman and installing a new monitor that requires no isolation, can I lose both of them? The lights run off of one of them too, but can't I hook that directly to the main AC? The current hacked jamma harness that's in here is patched into both transformers, but it looks like hell.
 
You should be able to Shawn. I'm running a Bob Roberts harness that's powering up my original PCB with the help of a switcher. I have an Iso in it however, for the G07.
 
Yeah, you can lose both transformers. The only thing you'll need to find a power source for after that will be the coin door lights - those run directly off the transformer too.

-Ian
 
Pacman upright did not use coin door lights. The Pacman cocktail did have them and so did Ms. Pacman table & upright.

The two transformers function as follows:

One had several secondary windings for powering the gameboard. That one can go bye-bye if you want (be sure to sell it to someone who might need it).

The other one is the monitor isolation transformer. It could stay regardless of whether your new monitor needs it or not. If the new monitor doesn't need it and if you don't want to use the transformer, you could remove it (also be sure to sell it to someone who could use it).
 
Oh yeah, I'll sell the transformers when the time comes. I wanna keep the original bulb sockets in the marquee area, I'll just be using CFL's, I can run that wiring into the main AC Line off of the switcher, yeah?
 
Is this an upright or a cocktail?

Normally I'm one who advocates keeping an isolation transformer in place even if the monitor you put in doesn't need one. It's 'original', it's extra protection in case you do something dumb later between the power input and the monitor, and great if you decide to drop back in a iso-requiring monitor later and forget that you don't have the iso. Yes, it costs a tiny amount in additional power usage and generates a small amount of heat.

But in the case of a cocktail -- I would actually remove it because it will help with preventing monitor distortions due to the proximity of the transformer to the neck/yoke.

A lot of people blame the card edge connectors or fuse blocks in Midway cocktails in creating hum bars on the monitor, but I've found that the iso or the step-down transformers that are inches away from the tube can also affect it.


Also for those doing this in a cocktail -- remember each bulb in the game uses about 1/4 amp of power, so you will have 1.5 amp draw if you have all 6 connected (2 per player, 2 per coin door if Ms.Pac style dual door, or 1 per coin door if a single entry original Pac door droping it to 1.25 amp) Make sure you have sufficient amp service on your switcher for either the 5 or 12 volt line for both the gameboard AND the lamps together, depending on the voltage of those lamps/where you plan on connecting. Put a multi-meter in place to measure the draw of either part to be sure you don't overload the switcher.
 
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Oh yeah, I'll sell the transformers when the time comes. I wanna keep the original bulb sockets in the marquee area, I'll just be using CFL's, I can run that wiring into the main AC Line off of the switcher, yeah?

The CFLs work great Shawn. That's exactly what I did in mine. When I put in the original marquee, that sucker is bright. The Switcher I put in was an old Peter Chow unit. 5V for the boards and 12V I'd have to check where that was used, but I just followed the Bob Roberts guide and used his method similarly.

Here's the link, very good information too:

http://therealbobroberts.net/mspac.html
 
Apparently those bigger transformers (for the voltage to the game PCBs and coin door lights) are sought after on the Bay. Bob Sokel - the TwoBits guy - told me that he's out of stock and people are asking for them.


Save the iso for some game project you pick up that has it stripped out...
 
I guess I'll have to find the Galaga transformer I pulled when I dropped the switcher in, unless somebody wants to make me an offer now...:D

ken
 
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