MKII Game works, No Picture Experts Please Help

TestYourMight

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I recently inherited a Mortal Kombat II Arcade Machine, It used to work, but one day we went to turn it on and the screen quickly came on and turned off. The sound and game still work fine, but the screen is just not there. When shut off for long lengths of time, it seems on start up, the screen seems to try to come on stronger then when trying repetitious tries. This problem still persists. Recently while looking in the back of the cabinet I found (what I'm guessing is a fuse) a little black cylinder shaped object with to prongs on it with some white glue residue on one side of the rim (pictured below hopefully) I noticed that there are a few of these things in various place on the boards. Anyhow, I'm hoping someone with some experience could tell what steps to take in order to fix this machine. I'm hoping its minor.

Any input and help is greatly appreciated, hopefully there are some images uploaded to this post.

Thank you again for any help!
 

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Hello, just taking the board out may open up near failing solder joints... Fixing one problem may bring another shortly down the road, it may already have multiple problems, or handling it will create more opens... best to rebuild the entire monitor boards is the good thing to do with that particular board. Good luck!
 
How do I go about this, is it something a newb with good common sense but limited electrical experience can accomplish? Or should I just pay someone to do it, I really don't have? the means right now. Is it costly? I'm really hungry for any information on this topic, thanks for the reply.
 
you're talking a cap kit, and a soldering iron, some solder, and a little bit of hope. lol :)

yeah, common sense can get this job done. I can show you the ways of the force if you feel up to it, but you gotta have a basic understanding of what you're doing first.

and knowing which kind of monitor chassis you got there. by the looks of it it's a Wells-Gardner K7000 -- VERY easy to work on.
 
That little black cylinder thing you're talking about is called a capacitor. There about a dozen and a half or so of those on the boards for your monitor. Their job is to regulate voltage for the various things that the board needs to do to get the image from your game to the screen. Where did you find the one that you took the pictures of? Was it just rolling around in the cabinet? Did it fall off? Did you pull it off? It's not very common to see a capacitor (cap) fall off.

There's been mention of a cap kit in prior posts in this thread. If bad capacitors are your issue, you're gonna have to replace them. Without being able to test which capacitors are bad, it's best to replace them all with a capacitor kit (cap kit) that you can buy just about anywhere. I'd recommend The Real Bob Roberts. Expect to pay about $20 for the kit shipped, and then you'll need to get your hands on a soldering iron.

Removing the circuit boards for the monitor involves the following steps:


  1. Discharge the monitor. Please Google how to do this. IMPORTANT! 20,000 volts!
  2. Disconnect the anode lead. (suction cup)
  3. Disconnect the dag wire, which is usually a black wire going from the monitor frame to the smaller board on the neck. This is the ground for the neckboard.
  4. Disconnect the neckboard from the tube. Be careful, as you don't want to crack/break the neck of the tube. Break it, and you'll pop the vacuum in the tube and you'll have a huge paperweight. I usually wiggle the board as I'm pulling gently and the board will come off the tube socket. There may be a glob of glue holding the neck socket on if the neckboard has never been removed before. Just scrape it away or cut it away with a razor.
  5. Unscrew the main chassis board (the big circuit board) from the base of the monitor. Usually 2-4 screws.
  6. Unscrew any other ground wires that may be attached to the monitor's frame. Make note of where they were attached so you can re-attach them later.
Once the circuit boards are out, you can Google or search Youtube for videos on the process of actually replacing the caps. Expect your first cap kit to take some time -- you really want to make sure you don't make any mistakes. Installing a cap backwards can have catastrophic results.

Here's one:



Your other option is to send off the chassis for repair to someone like Chad at arcadecup.com or Carl Blessing at Allgood repair, or Rick Nieman at Nieman Displays. They are all great guys, members of this forum, and willing to help as professionals. Expect to pay about $100 to get your chassis professionally repaired by one of them.

Otherwise, there are several forum members here that would be willing to recap the monitor chassis for you too, and at a lower cost. Trade-off is that they may not be professionals, but their work will probably be just as good. Each person charges different, some will even barter for other things. Modessitt is one such user.

Good luck!
 
Being a DIY kind of guy a big part of me is saying take the plunge and to try it myself, the other part of me says 20,000 volts is a lot and I'm not a big fan of getting shocked, nor do I want to damage any additional areas of the game because of my inexperience.

I found the cap laying on the ground, my guess is that it either came loose while moving the machine, or the heat got to it, being that it was in a garage for a while in humid FL (probably not the best idea) Anyhow, I'm pretty sure I can get my hands on a soldering Iron, and I'm pretty sure I can yield it. I'm hoping the force is strong with me, so if your up for it I'm willing to be your padawan.

BTW, what kind of catastrophic results can applying a cap backwards have?

Thanks for the detailed replies, can't wait to be doing some old school finishing moves!
 
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installing a cap backwards? it'll make a little *POP* and then it'll be no good anymore, that's all. might even smell funny for a little while. :)

the cap has two legs, one's + and one's -. the negative side is actually marked with a stripe spanning the side of the cap (from top to bottom). a lot of chassis at the install points for the caps will have markings that denote which end the negative leg of the cap goes in, but in the case of the K7000 this is not the case. on the K7000 the markings are for the POSITIVE side.

but that's how the polarity is determined.

when installing a cap kit, the most important parts to note are obviously the polarity of the cap installation, but also the ratings on the caps themselves. you can't just take a 50uf250V cap and throw it in where a 10uf50V cap goes. enclosed with the cap kit itself will be a sheet of paper with all the cap locations (like C12, for example) and which rated caps go to them. check which cap you're taking out to make sure you're pulling the right one... on some boards you'll find a few different caps clustered in the same area. :) the general rule with cap ratings is that the uf (uf stands for "microfarad", btw) number MUST be the same, but there can be variations in the voltage side. some newer caps are rated for higher voltage tolerances than the ones you're replacing.

I tell everyone taking the plunge for the first time to ignore all the experts on here that say "it should take no longer than 30 minutes". take your time, and do it right the first time.

that way you won't have to worry about popping caps, right?

and be extra careful with your solder work, don't ever "bridge" between two points that shouldn't be connected, otherwise you'll be one of those posters saying "I installed a cap kit and now it's blowing fuses".
 
installing a cap backwards? it'll make a little *POP* and then it'll be no good anymore, that's all. might even smell funny for a little while. :)

That may be true in some applications, but on the Atari ARII board I was working on, the 3300uf cap I installed backwards took out 3 diodes and 2 fuses when it blew like a bottle rocket. And yes, sprayed all over the inside of the cabinet like a jet. And smelly.

And scared my daughter too, who was standing next to the front of the cab when it exploded.
 
I feel I'm capable of installing the cap kit after watching a few how to videos on youtube, It seems Bob Roberts is the popular guy to get these cap kits from, although I'm not sure which kit I need for my particular monitor.

The only reservations I have about this project is the 20,000 volts going through the flyback. I've watched a few videos on discharging the monitor as well, and though it seems simple, still not worries me. I do have some alligator clips and an insulate screwdriver laying around.
 
honestly every K7000 I worked on never even made a crackle when I discharged them. I've probably worked on 3 of those now. I'm a real asshole with discharging now, I literally lift up an end of the suction cup when discharging.. of course not touching anything metallic :)

there's a single cap kit for the K7000.

I don't know if you've heard any of the legends about the K7000 flybacks before, but there's an older style flyback with white adjustment knobs (like yours) that is highly prone to failure, considering these things have been operating 17-20 years now.

I had a K7000 where the flyback took a shit, and it put a nice hole in my chassis. I had to replace traces and every major component (the flyback, the HOT, the C36 cap (which is where the traces blew), and the voltage regulator) ... so honestly, if you're going to cap this thing, you might as well change out the flyback too.

they're relatively economical to work on. I think Bob even has a deal on flyback/capkit where you actually save money on the kit itself.

also on a dedicated MK2 cabinet, your best bet is to remove the monitor from the cab before attempting to work on it. don't worry about the 20,000 volt shit... I think the K7000s had bleeders for that. in fact if you leave it powered off for a couple days, you won't even have to worry about anything.
 
So remove the whole monitor huh? Sounds fun, anyone got a step by step on that haha? Do I have to discharge the monitor before removing it? I was thinking about asking if I should just remove the whole thing because the support brackets that are holding the cpu boards for the monitor, and I wasn't sure if it was a good idea to have your arm near them while discharging, I was gonna wrap them in rubber.

I was planning on replacing the flyback anyhow, I came across a piece of research that pretty much said the same thing as you about this unit.

Sorry to be so inquisitive, just wanna make sure I have everything covered before taking the plunge, you say not to worry about the 20,000 volts ish, but its still in my mind haha, I've been zapped before so I'm a little reserved.
 
So I now realize that my previous post was kind of dumb, thanks to this helpful video

http://www.youtube.com/watch?v=01yUFKubIWY

So now I'm just trying to decide if I should go through the trial and tribulation and spend $30 on a cap kit with a flyback and hopefully borrow a soldering iron from a friend or buy a cheap one.

Or should I just budge and spend the $100 to a local arcade repair shop near me. I was really kind of looking forward to the challenge of doing it myself, but I'm worried that with my limited knowledge and limited soldering experience I might further damage the boards.

Again I'm only guessing a cap kit will fix it, mostly because I found a cap rolling around the bottom of the cabinet after it was moved.

Any more input on this subject is greatly appreciated, again thanks for all the detailed help thus far!!!
 
if you're having doubts, then I don't know... I guess you could pay someone else to do it.

one problem I ran into (consistently) with the K7000 was the orange glue they used around caps. there's readily available "cap maps" (basically a drawing of the chassis marking where all the caps are located) but I'm usually in a pickle where I have no printer to use, so I just draw my own maps while the iron's are heating up. :)

the orange glue generally covers the Cxx numbers on the chassis. dental pick is one of my tools of choice, cause I can scrape with them, and they're good (especially if you lack a desoldering iron) for sticking in the through-holes when you melt the solder and just wiggle it around inside the hole to clean them out.

you would also need a pair of electronic shears (or snips, whatever you call them) for cutting off the excess cap legs after you've solder the new ones in.

the flyback is where you would actually need a desoldering iron, cause with caps you can use a regular iron to alternate heating cap legs and just pull the cap back through... not so with a flyback. I personally use the Radio Shack kind, it's got a red bulb, basically you squeeze that first, then press the hole-tip around your solder joint, wait for it to melt, and then release the bulb and it sucks the solder out.

I don't know, maybe pay to get it done if you don't want to go through all this. you never know what kind of job one of those overpriced assclowns will do though, heh.
 
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