Mrs. Pacman help

[P-feif]

Today I found time to strip down my Mrs. Pacman. I bought it with a few problems and I'm determinded to get it working. So here are some things that I noticed and I'm wondering if you guys can help explain some of it. Keep in mind this is a Wells Gardner monitor (pic somewhere below).

This is the PCB. Notice anything missing? Isn't there suppose to be a gray ribbon cable with a daughter board mounted next to the PCB? This one does not have it and yet it still plays Mrs. Pacman. It clearly says Midway Pacman on the board and I know that Mrs Pacman is just a Pacman that's sort of modified. I'm wondering if maybe the original PCB died and someone fixed this game by installing a regular Pacman board with some Mrs. Pacman chips installed. I can see where there are chips that have hand written tags on them (Note: This game has a speed up mod so I don't know if the chips were installed for the speed up mod or to make this board play as a Mrs Pacman, or both)







Also this game has a piece of dark colored plexi-glass over the monitor screen, as it should, and with it in place I did not notice all the burn in that this tube has. Now that I've taken it out of the game it's easy to see just how bad the burn in is. It's bad so I don't know if I want to live with it or not but for now let's just assume that I'm going to live with it (if you have a good tube let me know). What I noticed is that the burn in is there twice. It looks as if thing has been through hell and back. I can see two differant types of fonts and two mazes, as if the image has been moved or shifted and then the game was used like that for a long time (again). This is another clue that this game has been broght back to life with this "other board" that I found in it (don't ask me how I didn't notice it when I looked it to buy it but it's what I have to with now).




Anyhow here's some more pictures just for fun and as long as I figured out how to post pictuers to the forum.







Notice that ground strap that's cut off? I can't find where it's suppose to go and I'm not even sure that it belongs there. Any Ideas???




Cut off ground wire? I am guessing that I should hook this back up? One end goes to the neck board. The other end goes to what I think is part of the degaus wires around the picture tube. At the neck board there is a second ground wire that also goes the the chasis as a ground.

[P-feif]

Hold on I just noticed a problem with some of my picture links. The computers being fussy about fixing it and I have to do it one pic at a time. Give me a few minutes.

[P-feif]

O.k. picture links are fixed. Let me know if you can see them too.

[lordkahless214]

it looks like someone did the daughter card elimination mod to the PCB, operators often performed the mod on MS Pacman because the reliability of the
game was poor due to the ribbon cable that ran from the PCB to the daughter card.
I have a PCB with this mod, and it is more trouble free than the one with the stock daughter card.

All MS Pacman PCB's are actually Pacman PCB's with different character roms and the daugther card.
I don't see anything to indicate your PCB has been swapped out, just modified.
(although it is certainly possible, IIRC there is a way of checking by matching PCB serial numbers to the cabinet)
here is some info on the mod http://www.pinrepair.com/video/pacman.htm I think it's mod #3

My explanation for your double burned monitor is a simple one, it appears like it was setup with the factory settings long enough to get burned in
and then sometime later, an operator readjusted the monitor to compensate for aging components in the monitor chassis
and then got the second burn, monitor image placement is all about settings on the monitor and not usually the PCB itself.

I see two cut wires on your monitor chassis, a tan wire near the power cord which in most cases would attach to any field ground (like the ground wire on the main AC power cable, or on the AC line filter ground)

and the black wire from the neck board, which should connect to the aquadag groundstrap wire, this wire is often cut to remove the chassis for repair, and can be reconnected with a wire nut or crimp quick disconnect terminals.

You lucked out getting a Wells Gardner 4900 in this cab, it is a good monitor and after a recap and reflow should provide a great picture and service for years to come.
Tube swaps are also possible if you can find a 19" TV with a compatible tube.

I always recommend that when someone gets a ms pacman that they check all the fuses and the fuse holders on the bottom of the game as they are often in need of replacement.
 
I hope I'm not getting too technical :-) Let me know if I am.

[P-feif]

No you're not getting to technical. I have a mild electrical and electronic backround mostly in the automotive field. This is totally differant but I am able to understand it and I'm trying to learn what I don't understand.

That's good that you think it's just a PCB mod to eliminate the daughter board because after looking at it, it made me start to wonder if such a thing existed. Now it makes sence. Everything I've seen about them says that they are just a pacman board. At first when I noticed that the daughter card wasn't there I thought "BOOTLEG BOARD", but then I saw the Midway Pacman logo and I knew that something had been done that I was not aware of. When I get some time I'm going to follow your link and read up on that.

Monitor wise I just noticed that the font looked differant in on set of burn in vs. the other set of burn in. I guess it could look like that if the picture was shrunk down so it is what it is. I've heard of using a TV tube but I have not been able to find one that fits the bill for this one. Even John had a list of compatible TV tubes that I read over. Either I missread it or it just didn't list one that would work. So if you know of a model that will swap please tell me. I'll start combing tv shops to see what they have lying around.

I have a kit from Bob Roberts with caps and the color transisors and resistors and a few other parts. If it still has no read tones then I guess that means that the tube is bad or I have no signal from the PCB. I guess we'll see what happens. I sort of bought this thing so I would have a good candidate to get practice on so I just decided to go ahead with the monitor rebuild. Wish me luck.

That tan wire that you spoke of is acutally a bare uninsulated strap. I'll have to try to figure out where you think it should be attached. The black wire I kind of figured it was cliped so thanks for you conformation. It will get and insulated spade connector.

Thanks tht ought to get me going for now. Believe me I'll be back with more questions.

[lordkahless214]

I wanted to provide a few links I felt may be of use to you, they really helped me in my early days and some are related to Ms Pac

First, you may want to check out Bob Roberts' page on AC wiring, it has a photo of the AC line filter I was talking about and, while written for someone using a switching power supply, is still useful to help you troubleshoot some of the wiring in the AC section of the game , it's here http://arcadecontrols.com/BBBB/acwiring.html In the case of your monitor, I would recommend replacing the cutoff bare ground strap with a new ground wire, I use green wire for AC circuits you can get at home depot cheap, I got a whole roll for like $5.
and I swear it looked tan  but then the monitor on my laptop isn't the best.

Also be sure to check the fuses on your monitor chassis, those can and do fail as well on 4900s I think they are soldered in and often covered with plastic clear (now yellowing) tubing, if the HOT and or flyback has gone bad they can take out the fuses.

Here is a page on pacman, I often recommend this page for people, it has general information on fixing pac boards and other things relating to these cabs http://lawnmowerman.rotheblog.com/

I have heard that Sanyo 19" DS19390 model TV's have a compatible tube in them. I wish I could be of more help with the tube swapping, but I have yet to perform one, like you said you can just visit tv shops or thrift stores and maybe you will get lucky. Once you get your monitor going you will be able to decide whether you are unhappy with the image enough to swap it out.

[P-feif]

Actually the entire game was working. The monitor just had no red tones. So I'm just doing a full rebuild to fix it and make sure that I minimize future problems, or at least what bob roberts says is a rebuild.

Thanks for the info. I had found the lawnmowerman site, it's great, but I hadn't seen the A/C wireing one from bob roberts so I'll make sure to look that one over. If I happen to find one of those tv's I'll let you know if the tube fits or not.

Yeah, I found the soldered in fues. I just shook my head. Why would you solder in a fues?

[P-feif]

This is for anyone working on a WG4900 monitor like I am attempting. I wasn't sure where some of the parts went that Bob Roberts sent me so I sent him a note and he was kind enough to reply with the answer that I needed. Along with his answer was this link on how to install a filter cap in the corner of the board, so I thought I would share that link for anyone that needs it. When I looked at my board I just couldn't see this small cap replacing the monster cap I was looking at. I should have gone with my instincts but at the same time I'm also glad I played it safe.

http://www.therealbobroberts.net/wg49.html

I'm going to look in the factory Mrs. Pacman manual for a monitor schematic but if it's not there does anyone have a link to one on-line?

[John's Arcade]

I haven't read everything but I did notice the filter board between the PCB and the harness. Remove that. It's not needed and causes all sorts of problems.

[P-feif]

I think it's already gone. What do you know about the yellow ground strap that runs from the coin door area to the PCB area? In mine it's disconnected and I think I remember reading somewhere that it was to stop some sort of RF interference. That sound right? Hook it back up or leave it off? And what does it hook to because I haven't found a spot that looks like it should go to?

With a little luck it'll start raining soon and I won't be able to work on outdoor projects which mean I can work on Mrs Pacman in the basement.

[P-feif]

Ha! Bob Roberts just sent me an e-mail saying the 330uf 200v cap he sent was the wrong one and he's sending me a 470uf 200v cap to replace it. I guess it's a good thing I sent him that e-mail asking for board locations for some of the other parts he sent.

Between Bob Roberts, the John's Arcade video's and forum I'm getting things figured out. Thanks to all that have helped. I'll keep asking questions and when I get it working I'll have to post some pics or maybe a short video too.

[John's Arcade]

I think it's already gone. What do you know about the yellow ground strap that runs from the coin door area to the PCB area? In mine it's disconnected and I think I remember reading somewhere that it was to stop some sort of RF interference. That sound right? Hook it back up or leave it off? And what does it hook to because I haven't found a spot that looks like it should go to?

With a little luck it'll start raining soon and I won't be able to work on outdoor projects which mean I can work on Mrs Pacman in the basement.

Oh. sorry. You are right the filter board is gone.

The ground strap goes somewhere. I would just ground it to the closest screw.

[lordkahless214]

Here is a link to the monitor manual for the 4900 series monitors, it includes schematics http://www.vernimark.com/arcade/archive/monitor/mon_rc__wg-19k-4901-06-51-56.pdf

The yellow cable used to hook up to the now removed filter board, since it's gone just do as John recommended and run it to a ground screw.

[P-feif]

O.k. I've seen pictures of the filter board. If I can find a ground for it I'll use it otherwise I'll just tuck it off to the side and leave it unused.

Thanks for the link! I printed that!

[P-feif]

O.k. finally found some time to work on this monitor. I've got about 75% of the caps replaced and still need to do the color transistors and a few resistors and the rest of the caps. When it's done I don't want to reinstall the monitor untill I can replace the missing leg levelers. It's much easier to tip the cabinet now with no monitor in it. So my question is, where can I get leg levelers for this Mrs. Pacman and while I'm at it I'll get some for my Space Invaders too?