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Arcade Collecting => Miscellaneous Arcade Talk => Topic started by: WunderCade on July 22, 2007, 01:41:25 pm

Title: Refurbing a MS. Pac-man Power Supply Board
Post by: WunderCade on July 22, 2007, 01:41:25 pm
Has anyone ever refurbed their Ms. Pac-Man main power supply board with modern parts? I think my Ms.Pac power supply is shot, it looks simple enough to duplicate, but I am not sure of what is modernly available to refurbish it ie. transformers etc. My cursory search for the transformers didn't come up with transformers that look anything like what is on the board.

Perhaps someone has knowledge of a project like this and can link to it? Thanks.

This is what I want to refurbish:
(http://forum.arcadecontrols.com/index.php?action=dlattach;topic=51525.0;attach=79091;image)
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: BobA on July 22, 2007, 05:26:47 pm
You are showing the standard pacman/mspacman PS transformers.  The top one is the isolation tansformer for the monitor and the bottom one is the power for the PCB.   The transformer supplies 7 vac and 12 vac to the PCB.  If you use a multimeter and check the output of the transformers you will be able to determine if the transformer for the PCB is good or bad.  If it is good there is no need to replace it.  The power regulation is on the mspacman board and that is where you check for regulated voltages if the AC input voltages to the PCB are OK.

There is a mod to change the ps to the mspacman board from AC to a new arcade DC supply.  This involves bypassing the regulation on the mspacman board and I do not know the details of it. 

 
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: WunderCade on July 22, 2007, 05:32:42 pm
Good idea, I'll check it since I do have a multimeter. 1 other question, I know how to check current across a capacitor +,- , but when checking current from the transformer, would I just put the black probe to a ground and the red probe onto the hot wire coming from the transformer?
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: BobA on July 22, 2007, 05:36:08 pm
When your multimeter is on ACV it does not matter which probe is on which lead as the voltage is AC not DC.
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: RayB on July 23, 2007, 02:29:56 pm
Step 1: Clean off all the dirt
Step 2: Make sure there are no shorts (short circuits) and remove that piece of metal that could short everything out.
Step 3: what they said above.....
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: ChadTower on July 23, 2007, 02:32:22 pm

The perspective on that photo makes the inside of that cab so much bigger than it is.
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: Level42 on July 23, 2007, 03:56:24 pm
I would suggest removing that metal strip under the blue plastic first.....could short something !!
Looks exactly like my Galaxian PSU board. But mine is a bit cleaner.

Clean everything, check fuses (are they the correct types and are they ok ?), measure transformer outputs.
Clean the fuse holders (especially where they contact the fuse) and feel if they're "tight" over the fuses...

This thing is so simple, it's not very likely to fail. Just two transformers with a bunch of fuses and a mains filter.

Chad, it looks so roomy because I guess there's no monitor inside ?
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: ChadTower on July 23, 2007, 03:58:07 pm

Would it read the same with no load as it would with one?
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: JeepMonkey on July 23, 2007, 04:55:06 pm
... I know how to check current across a capacitor +,- ,

Correct me if I am wrong, but shouldn't you measure current in series.  Measuring current in parallel, as it sounds like this is what you are saying, can blow a fuse in your meter.

Voltage can be measure in parallel, or from source to ground.
Title: Re: Refurbing a MS. Pac-man Power Supply Board
Post by: ChadTower on July 23, 2007, 04:57:13 pm

He would be checking capacitance on a capacitor, anyway.  I'd think that since a capacitor is not designed to limit current, the current reading would be the same in front of as behind it, just a bit smoother coming out.