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No power to Pac-Man monitor

cerkit

cerkit

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Montgomery, AL USA
I just acquired my first arcade cabinet, a 1980 Pac-Man cocktail cabinet. However, when I plug it in, I only hear some crackling from the speaker for a few seconds and then silence. There's no picture on the monitor or sounds coming from the game. I measured the voltage on the power cable and it's 120v (my house is a little on the high side). I replaced all of the fuses and checked the voltage on the monitor cable. It was less than 5v. I then checked the voltage on the monitor transformer and I'm not getting the expected 115v.

I'd like to do a power supply conversion, but all of them tap the monitor voltage.

I've studied the schematic in the manual and I think it may have something to do with the filter, but I'm not sure what pin is what on that component.

I am an electronics hobbyist, not a professional, so my knowledge is limited.

Based on what I've tried already, does anyone have any ideas on how I might proceed? If I can, I'd like to continue to use the existing power supply. At the least, I'm going to have to find a way to get that 115v to the monitor.

Thanks.
 
OK. You checked the voltage on the power cable that plugs into the monitor and its feeding the monitor 0v?

First thing is to get the monitor working. Cant troubleshoot the PCB until you can see what's going on.
 
Midway games have a lot of issues with the older fuse blocks. I've had to replace them on a number of occasions, but your mileage may vary. Like Mitsu said, follow the AC voltage through the transformer and see if you can nail down where you're losing it.

Go here for a generic lesson on how the AC wiring in a typical arcade machine works.

http://arcadecontrols.com/BBBB/acwiring.html

It won't be exactly like your Pac, but it should give you at least an idea of what to expect.
 
I haven't read the link you sent, yet, so hopefully the answer will be in there.

I just measured the voltage going into the filter and it's ~115v. However, coming out of the filter and into the transformers it's hovering around ~5v (it should be ~115v). So nothing in the cabinet is getting power. When I got the cabinet, the ground pin on the plug had been removed, so I replaced the plug last night.

Are these filters necessary? Can I safely remove it or should i find a replacement?

Edit: I just read the link you sent me about power supplies and it includes the filter. I guess I'll just build a new power supply. I'm assuming isolation filters are easy to get. I was worried that they would be hard to find.
 
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I did some more troubleshooting today and I have to admit that I'm a little embarrassed. I took the power supply and harness out of the cabinet so I could work on it on my bench. I hooked it up to power and there was nothing. I then looked at the schematic and realized that I had to "close" both the safety switch and the power switch. Once I did this, I had the correct voltages on the transformers. So I went out to my cabinet and looked at the safety switch. Sure enough, it was in the "off" position. I didn't know that this cocktail table's safety switch works just like the stand-up cabinet. I pulled the lever out and did a continuity check on it and it was fine.

I was testing voltages with the safety switch turned off the whole time. So, it wasn't the filter.

To make things worse, I made a rookie mistake and actually cut wires on my harness to get it out, thinking that I'd reuse the molex connectors for the player 1 and 2 consoles as well as the coin door and monitor cables. I spent two and a half hours soldering the harness wires back together again.

ArcadePacManResolderingHarness.jpg

With the power supply assembly on my bench, I tested the voltages across the fuses. They were terrible. As you can see based on the image, there's a good reason for that. So, I ordered two 4-fuse fuse blocks from Amazon. As soon as they get here, I'll reconnect everything and try again.

I took the opportunity to clean everything up and wipe down the wires. This cabinet spent many years in smoky bars and there was a layer of grime on the harness. It was so bad that I couldn't tell the colors of some of the wires.

ArcadePacManFuseBlock.jpg
 
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Lol! Yea, those damn interlocks still get me from time to time too. Glad that worked out on that part. Once you get those fuse blocks replaced, hopefully you'll start getting some signs of life!
 
Yeah the first step in any Pac/Ms. Pac troubleshooting is the change the fuse block out with a new one. Good luck!
 
That is one ROUGH fuse block. I just rewired a Pacman cabinet as part of a deconversion. Let me know if you have any questions.
 
I got the fuse block replaced and now I have signs of life. Unfortunately, it's just a screen full of characters and bits of sprites. That's my next project.

Here's the after shot:
FuseBlockAfterReplacement.JPG

I decided not to solder the wires to the fuse block to make it easier to remove the harness in the future
 
I repaired 3 pacman boards about 2 weeks ago to get a board for this restore I am doing. If you hit a wall, post a pic of what you are seeing and I'll see if I can help diagnose.
 
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