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Author Topic: Ms Pacman Fuses  (Read 8919 times)

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JeepMonkey

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Ms Pacman Fuses
« on: April 07, 2007, 12:02:46 pm »
Recently I purchased a non-working Mc Pacman.  I checked the four fuses my the transformer on the floor.  It calls for (2) 1A fuses and (2) 5A fuses.  Upon inspection, there was a 5A, 15A, 20A, and 30A.  My first fear was that there was a short that was blowing fuses, so someone put in bigger fuses. So I replaced the existing fuses with the correct size.  Turned on the power, fuses didn't blow.  Wonderful. 

At this time, the coin door lights work, they are geting a good 12VAC, and I can hear the moitor, no picture.  I measured voltage in parallel across all of the fuses, each showed zero volts.  The power for the coin door must be coming from somewhere other than these four fuses.

In my search, it seems that there should be more than these four fuses, but I can't find them anywhere.  I have seen pics that show a two or three fuse holder a few inches from the four fuse holder, but there is nothing there, and does not look like there ever was.

Any help would be appreciated.

Attached quote below for reference.

Ms. Pac coin door lights are lit by 12 volts AC from one of the power transformers in the back of the machine. You probably have a blown 2 amp slo-blo fuse or maybe even a cracked fuseholder clip. There are 2 banks of fuseholders in the machine: a bank of 4 fuses and a bank of 3 fuses. The one for the 12 volt lights is located in the 3 bank.
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modessitt

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Re: Ms Pacman Fuses
« Reply #1 on: April 07, 2007, 07:55:03 pm »
Well, first of all, those fuses were incorrect and you were right in replacing them.  If there was no problem with the voltages, you might be okay, but it's entirely possible your board is dead if an overload went through on your +5V line.

There were later versions of Ms. Pac-Man that used different power supplies (and sticker art instead of paint) that didn't use the extra two fuses.  Is it a big metal block on the bottom of the cab (four fuses), or is it just some transformers and fuses screwed to wood (6 fuses)?  I guess if someone was screwing with the fuses, it's possible they removed the other two and hard wired it.

On the older versions there is usually a 2-amp fuse in line from the plug to the transformer.  There is a 1 1/2-amp fuse controlling the coin door lights.  Then there are two 1-amp and two 5-amp fuses controlling power to the board.

Measuring in parallel across fuses isn't going to give you any readings.  This is DC voltage and you wood need to put your black lead on ground with your red lead on your fuse to test your voltages.  It's better to clip your black lead to ground and measure with your red lead at your edge connector (with it disconnected from your board) to make sure the voltages are getting there properly as well.  If so, then plug your edge connector back on (with power off) and (power on) check for the voltages on your board, first at the edge connector (to ensure good contact) and then across your board.  I believe pin 1 on all the chips is the +5 pin but I might be backwards.

I would also verify the monitor does work by hooking it up to another game.  Does it make any sounds when you hit the coin switches?  Is the volume turned down?  Are all the chips seated firmly and the daughter cards in place, seated firmly, and with the proper polarity?

Once we are ensured of proper voltage and working monitor, then we can move forward with troubleshooting the board.
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Re: Ms Pacman Fuses
« Reply #2 on: April 09, 2007, 04:46:03 am »
This site might have more info on Pac-Man Boards:

http://users.adelphia.net/%7E68hc11/pacfile/pacfile.htm

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Re: Ms Pacman Fuses
« Reply #3 on: April 09, 2007, 10:32:30 am »
The other group of fuses are located underneath a gray "fishpaper" (cardboard) cover to the left side of the transformer board.

Is this an upright or a table cabinet?

JeepMonkey

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Re: Ms Pacman Fuses
« Reply #4 on: April 09, 2007, 08:23:16 pm »
This is an upright.  I did not look under the fishpaper.  I will check that out when I get home in a couple weeks.  Does anyone know what these fuses power?

I was able to read 12VAC across the front two fuses, 1VAC on the third fuse, but 0VAC on the back fuse.

Thanks all.
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Re: Ms Pacman Fuses
« Reply #5 on: April 09, 2007, 11:51:36 pm »
Im shocked no one suggested you download the manual and schematics. Also, the fuse ratings are usually indicated on stickers right on the fuse holder.
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Level42

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Re: Ms Pacman Fuses
« Reply #6 on: April 10, 2007, 09:03:10 am »
Does a Ms. Pac use the same power supply configuration as a Galaxian ?

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Re: Ms Pacman Fuses
« Reply #7 on: April 10, 2007, 10:41:37 am »
I have downloaded the manual and the schematics.  I didn't see much on the fuses as far as where they were and how many.  The scematics show the fuses, but it does not say which fuses are which or where they are moounted.

Level42 - I had the same question.  I have not been able to research this in depth, but I wouldn't be suprised if they were similar.  Do you know the layout of the fuses for a Galaxian?
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Level42

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Re: Ms Pacman Fuses
« Reply #8 on: April 10, 2007, 10:51:08 am »
I have downloaded the manual and the schematics.  I didn't see much on the fuses as far as where they were and how many.  The scematics show the fuses, but it does not say which fuses are which or where they are moounted.

Level42 - I had the same question.  I have not been able to research this in depth, but I wouldn't be suprised if they were similar.  Do you know the layout of the fuses for a Galaxian?
I looked at some pictures of baksides of Ms. Pac mans and indeed it looks pretty much the same.

Which would figure because Ms.Pac Man is essentialy the same like Pac Man hardware wise, and Pac Man is at least LIKE Galaxian.

Yeah I think I can give you that info....should be on-line as well though...  www.klov.com ?

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Re: Ms Pacman Fuses
« Reply #9 on: April 11, 2007, 04:19:14 pm »
There are about 6 fuses in those old Pacman machines.  I stripped a couple of them.  One from the main line, one to the marquee, one to the monitor, and one for each of the AC's comming off the transformer.

The transformer is the source of all power if I remember right.  If the voltages are okay on the transformer then it's cool, you can short over the fuse to test. 

You did note that there is a shut off switch when the door is off right?

A lot of times you can't tell if a fuse is good with a continutity test in the machine itself.  You have to take it out and test across it.  You want to use only the continutity test. Not a resistance test.

Can you test the monitor?  Do you know how to test for a video signal from the board?

If that machine had a board that works in it, I'd be shocked. That is rare.



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Re: Ms Pacman Fuses
« Reply #10 on: April 11, 2007, 05:34:10 pm »
OK, it's a bit strange.....I checked the parts and operating manual (http://www.arcadedocs.com/vidmanuals/M/ms_pacman_p4.pdf) and on page 75 you see the part of the schematics of the power supply. Here you can find which fuse is which. I guess you will have to look at the wire colors to identify them...

As far as I can see it's almost identical to the Galaxian Power supply. The only real difference is the value of the lowest 12V tap, because Ms.Pac Man had lit coin inserts, where Galaxian doesn't. The fuse is 2 Amp on the Ms. Pac, 1 Amp on the Galaxian.

Further it looks the same to me. However, I count 6 fuses in total on that schematic, but on page 49 there's a picture of the power supply board and this shows 7 fuses total...........

Remember that the PCB is being powered with AC (12V and 7V). This is converted to DC on the PCB itself.

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Re: Ms Pacman Fuses
« Reply #11 on: April 12, 2007, 09:38:20 am »
I was able to read 12VAC across the front two fuses, 1VAC on the third fuse, but 0VAC on the back fuse.

If you can read voltage 'across' a fuse, that pretty much indicates the fuse is open.  A good fuse will show close to 0 volts 'across' it.

If I'm interpreting 'across' correctly.  No promises there.

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