UMK3 Black Screen

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    • UMK3 Black Screen

      I have an UMK3 board that used to work now its giving me black screen when turning it on .....
      Cabs: Sega Naomi Universal,Neo Candy 29,Neo Geo MVS U4, Neo Geo MVS U2, MK2,Tekken Tag,Killer Instinct
      AMB:CPS1,CPS2,CPS3,Namco 246,Naomi 1,Sega STV,NG-4 slot,Atomiswave,Taito Type X2.
    • Vladi wrote:

      I have an UMK3 board that used to work now its giving me black screen when turning it on .....
      do you get the boot up gong through the speakers?

      IIRC there is a button you can hold or a dip you can throw to get a diag beep code on boot.
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    • i removed the u 64 security chip and it still does not boot. I think it must have been the yanked 5 volts busted the board . does somebody knows which components of the board can get busted by excessive volts.
      Cabs: Sega Naomi Universal,Neo Candy 29,Neo Geo MVS U4, Neo Geo MVS U2, MK2,Tekken Tag,Killer Instinct
      AMB:CPS1,CPS2,CPS3,Namco 246,Naomi 1,Sega STV,NG-4 slot,Atomiswave,Taito Type X2.
    • Vladi wrote:

      i removed the u 64 security chip and it still does not boot. I think it must have been the yanked 5 volts busted the board . does somebody knows which components of the board can get busted by excessive volts.
      That's difficult, because on JAMMA boards, usually most of the chips are connected directly to the +5V line, meaning that if you send an overvoltage there, almost any of the components get the overvoltage without anything between, which means they can get fried easily, usually more than one.

      Regards.
    • I've got an UMK3. they are big boards which are troublesome.
      Try pushing on the custom chips, holding and booting. Do one chip at a time.
      Try pulling the program EPROMs, cleaning the pins with some fine wet&dry sandpaper or a pencil eraser and putting them back in.
      If that doesn't help your board is essentially dead unless you (or someone) starts doing repairs at the component level.
    • Your U45 (Custom Altera chip) is probably burned. Replace it with a PLCC extractor tool if you have a spare and check.

      I've repaired couple of UMK3 boards. One of them had many ram chips burned, some EPROMs missing, and some more problems. Even with that, you should be able to see the colorful garbage screen as soon as you switch on the board. If you do not see it, and if your board is getting power from JAMMA connector (i.e. the red LEDs light up) I'm pretty sure your U45 is fried.

      Check for a burned hole on the chip which they generally blow up physically...
    • He said it worked so there's no missing parts and he didn't mention any burning parts either.
      Not sure where/when he 'yanked' 5 volts, there's no mention of how or why.
      Anyway, those boards are pretty complex and difficult if not impossible to repair by the average person.
      Meaning....
      If the FPGAs/CPLDs (the 3 square chips in sockets) are bad the board is toast.
      If the protection chip is bad the board is toast.
      If any of the surface mounted custom chips, RAM or logic is bad the board is toast.

      Some things you can do...
      ***carefully*** pull the FPGAs/CPLDs out of their sockets using a PLCC chip puller (NOT A tiny screwdriver!), clean the pins and push them back in (most people will make it worse and break the sockets and basically kill it dead right there)
      Pull the program EPROMs and read them in an EPROM programmer to see if they match what is in MAME (this is where the MAME source comes in VERY handy)
      Pull the PAL and clean the pins and put it back

      failing all of that the board is going to remain dead unless you get some professional assistance.

      this same advice and my previous post above also applies to most PCBs made between about 1990 and 2005
    • I would try all suggestions and don't condemn your pcb to death until it has been absolutely proven. Everyone needs to start somewhere and something as simple as pulling and cleaning eproms for troubleshooting is a great place to start. The problem is that there are VERY FEW people still repairing arcade pcbs. The one's that do are swamped with work and may not even be taking repairs anymore. I really wish there was someone nearby that I could do an apprenticeship with to learn more about component level repair. Even the local colleges no longer offer electronics repair courses and have not for years. I will sometimes drop by the old TV repair shop and talk to the guy there about repairs. They never get old TVs to repair anymore and he loves to talk about old CRT problems and when he used to repair PC motherboards.

      The problems I have run into a lot with the companies that claim to do arcade repairs still are these:

      1. Don't want to work on games that are not current
      2. I'll ask this: "Can you take a look at my Revolution X pcb?" Their answer: "We don't have schematics so No." (This was a guy who did repairs directly for Midway throughout the 90's into the early 2000's!!)
      3. They may do troubleshooting and find a bad custom chip and come back to you with "unrepairable" Bullshit. You can pull one off of another parts board. There is always a way. If you can diagnose the problem you can find a way to fix it.

      There are guys like Channelmaniac that will do all they can to fix your pcb and exhaust all options. Problem is they get swamped. I honestly don't know who will accept repairs anymore.

      I will say this. Anyone interested in learning how to repair pcbs don't get discouraged. Ask a lot of questions. Get your hands dirty. Try to find some electronics classes online or something. The first time I tried to fix a monitor I dropped into a monitor repair section on Star Tech Journal's old site. I mentioned I wanted to teach myself how to repair monitors and asked how to fix the issue I had with my monitor. The first response was from a veteran. He said "Teaching yourself monitor repair is like teaching yourself to skydive. It's dangerous and you shouldn't do it." I was crushed. What I was thinking was:

      1. No it isn't anything like that
      2. Fuck you

      About a week later another member kindly posted a message of how to fix the issue. He taught me how to discharge the tube. And it was my first time replacing components on a pcb. He answered all my noob questions. The monitor was fixed and has run perfectly for 15 years now. I never felt prouder the moment I flipped that game on and Virtua Fighter was playing perfectly on my monitor. Now I am pretty good at fixing CRT monitors. I even have a tube rejuvenator/tester. My point is: everyone starts somewhere so I try to support even the noobs whenever possible. No one wants to visit someplace full of "elitists" who won't help people out. We are a niche hobby. We should all have each other's backs.

      PS---I have 10 Rev. X pcbs that are all dead. Anyone want to look at them. My cabinet stays in storage until I find a working pcb....
      PPS--Good luck fixing this pcb. :P
    • yes everything can be fixed and you could get a custom chip from a parts board IF you can find the fault. that's the big IF.
      repairing is very very easy. finding the problem is not.

      Fixing PCBs and monitors is a lot different in my opinion. PCBs are digital with hundred of parts, many of them custom and all of it is unknown circuitry because there are no schematics. whereas with a monitor the circuit is infinitely simpler and there are less parts and most of it is off-the-shelf except the flyback and even then there is still one company making replacement flybacks so you could get that too. the problem with monitors is you can replace parts but if you miss something you power on and it blows up again taking out more stuff. you can start a fire or get zapped or worse, dead. that's why the guy gave you that advice.
      anyone who wants to learn will get past that and just do it. this is mainly because now there is the net to fall back on and get lots of technical info and help. to do it properly you have to dedicate time, sometimes a life-time to the subject. this is why for example, guys who do body-building don't have a hobby playing and fixing arcade games in their spare time because they don't have any spare time.

      there are places to start and a Mortal Kombat 3 isn't the right place. dead boards are the worst kind to fix because it means the program isn't running and the fault is in the CPU section or with some logic controlling the CPU and/or main work RAM. in most cases the PCB will just be resetting (watch-dogging) which means you have to disable that first before you can start otherwise all you see is a reset every 1 second. you also need proper equipment and some knowledge about digital electronics and how to read logic tables to find out what it should be doing. All that goes out the window if you are looking at a custom chip problem, assuming you can actually narrow it down to the custom.

      To give an example, when I started repairing stuff I got hold of an original Missile Command. It was dead.
      I looked and looked and looked and prodded and probed and got no-where.
      I put it away in a box.
      7 years later I pulled it out and fixed it in 10 minutes and I still have it here now and it still works 15 years on.

      there were other times when I couldn't find the fault and went away and a couple of days later I looked again and found it, or did some research and got some ideas which helped.
      but there were other times when I got so frustrated I changed every chip on the board including many custom surface mounted chips and it still didn't work! at that point the board was basically fucked but I wasted a month on it.

      The moral of this story is the MK3 should go in a box and he should look for a working one on eBay if he wants to play it now, or he should get some help locally from someone who knows about board level repairs on complex surface mounted PCBs.

      Not saying don't do it, just saying don't make it worse ;)
    • PCBs have gone the same way as modern cars. before you could play and fix it.
      now you can't even see anything and what is there requires an expensive specialized diagnostic computer because people who are mechanics are not that technically minded (they can't fix PCBs at the board level). all they do is find out which bit is bad and changed it (including the whole computer if necessary).
      no one fixes anything nowadays, it's all throw-away and replace.
      basically the only thing we can do now is put in petrol, oil and water and change the filters occasionally.

      you don't need to go anywhere to learn, you learn it yourself by just fixing broken crap and reading books and/or web sites about electronic theory and repair. but you get to a point with the theory and then you don't need to know more. you'll never need to know how to design electronic circuits to fix stuff. all you need is to know the basic problems and how to fix them. I can list those here in order of checking..... (which is also order of easy to hard)
      1. clocks (measure oscillators, crystals etc with frequency counter)
      2. CPU (check operation/activity including reset signal on power-on)
      3. connections (including connectors, sockets and loose legs on large surface mounted chips)
      4. RAM (piggy-back RAMs, replace if bad, guess and replace suspect chips if surface mounted)
      5. ROM (remove, read and compare to MAME CRC32)
      6. logic (TTL databook and logic probe is all you need)
      7. custom chips (i.e. check for loose legs & re-attached, replace chip if very hot/bad)
      8. broken tracks (this is where it gets VERY time consuming and difficult)

      this would be on a PCB with no damage. obviously if you can see a bad custom chip or broken track then you go for that.
    • i ordered a PLCC extractor tool to check if it is the u45 chip . Ill post something when i do the diagnostics.
      Cabs: Sega Naomi Universal,Neo Candy 29,Neo Geo MVS U4, Neo Geo MVS U2, MK2,Tekken Tag,Killer Instinct
      AMB:CPS1,CPS2,CPS3,Namco 246,Naomi 1,Sega STV,NG-4 slot,Atomiswave,Taito Type X2.
    • Vladi wrote:

      i ordered a PLCC extractor tool to check if it is the u45 chip . Ill post something when i do the diagnostics.
      What about a replacement U45? I mean even if you take out the U45 the board will not boot anyway. It is the custom graphics chip. You have to have a spare working board MK3 or UMK3 to take out a confirmed working U45 and test it on this board.

      Be "very" careful with the PLCC extractor. If you apply too much force without control, the grips may slide and damage the pins on the corners.

      Like this:

      1) Grap the chip firmly from the corners. There are spaces there for the tool. Apply a controlled force so that the tool is not loose to slide but not too much tight also. Then like a dentist taking out a tooth slightly move back and forth so that the pins get loose from the socket. If there is rust, you can apply WD40 spray before this...



      2) When the chip is loose take it out carefully. As you can see the tips of the tool is so close to the corner legs. Be careful...




      Sometime the legs of these chips tend to bend slightly inside making poor contact with the PLCC socket. Sometimes the PLCC socket plastic gets old and become loose or cracked (due to constant heating and cooling) and causing loose contacts. I've seen UMK3 boards where the previous repairer just wrapped the PLCC socket with two plastic zippers :)

      Example (Infact this is a MK2 PCB but you get the idea):