Killer Instinct Graphical Glitch Repair

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    • Killer Instinct Graphical Glitch Repair

      Hey @Asayuki,

      From our earlier discussion, so I reburned the sound & boot roms. The graphical glitch remains. The board is 100% fully functional otherwise including audio, test screens, joystick inputs. Upon plugging in the board to my cab, I could hear the monitor sing with the sound of knives being sharpened. This does not happen with the 2nd Killer Instinct board that I acquired, which works perfectly. The graphical glitch exhibits a dark image and an unstable wave across the bottom 3rd of the screen.



      Any help would be appreciated sir!
    • Sound ROMs don't cure graphic glitches :)
      First of all don't connect it to a CRT monitor for the time being. During the repair you are much better off using an LCD monitor with or without a scaler in between.
      I would bet on the sync and RGB video outputs being low in amplitude, distorted, glitchy or jittering. If you have a scope around, then a screenshot of said signals would be very good. In any case try and follow sync, red, green and blue to their output stages on the board. Something is fishy in there. Check the power supply around for ripple, look for scratched traces, loose joint, cap leaks...
      BTW, do vibrations affect the issue?
      My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
    • Asayuki wrote:

      Sound ROMs don't cure graphic glitches :)
      You are right. Forgot to add that I reburned the sound ROM's and replaced the HDD as per your advice. Still no joy.

      So I grabbed the PCB by diagonal opposing corners and waved it gently as the game was playing. No difference. I suppose you would say that had there been a difference, then that is a cold solder joint somewhere and a potentially easy fix, yeah? The scope you mentioned is an oscilloscope? I definitely don't have one of those. In lieu of an oscilloscope, is there another alternative device I can use? Some sort of probe? If so, can you recommend one? I'll check those leads & traces from R, G, B, and Sync and report back. You're a great value here and elsewhere. Thanks!
    • I typically do something easier to check for loose joints: hit the board here and there with the handle of a screwdriver (which is typically rubber-ish). Yes, it's always worth to go for a good visual inspection and to check for loose joints as a first thing. Not because of the possibility of an easy fix, but rather because hunting something by probing and testing which in the end reveals itself as being a loose joint is not only a pain in the ***. It also makes you want to die once you realize how much time you invested for a thing *that* easy. ;)
      Yes I mean an oscilloscope, and no there is nothing else that can replace it. All I can suggest if you don't have a scope is to check the capacitors. If that doesn't help, then you need to start assuming things which is like a blind walk.
      My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
    • Asayuki wrote:

      All I can suggest if you don't have a scope is to check the capacitors. If that doesn't help, then you need to start assuming things which is like a blind walk.
      So here is a high res photo of the board. From what I can see, there is only one large cap circled in yellow. There is something else circled in purple, is this a polymer-based cap? And what are the things boxed in yellow? I ask this hoping you can narrow down the area where I should start looking around.

      The post was edited 1 time, last by acblunden2 ().

    • The thing circled in purple is actually a crystal, not a cap. The big yellow box is probably a series of resistors and diodes for the inputs. A lot of older pcbs used resistor arrays for this but this pcb uses almost all smd components instead. The electrolytic smoothing caps are replaced with smd caps as well.
    • I figured as much. I see many of the parts in the yellow box prefixed with a "C" which is usually reserved for capacitors. I am tempted to pick up a Rigol oscilliscope just to fix this board. I would probably break even on the cost if I can repair this board. I would very much like to repair this board. Actually, the world needs me to repair this board because KI boards are pretty hard to come by.
    • Hi,
      complementing what Mitsurugi already said: the big cap in the upper right is probably filtering the 12V power supply to help surges from the audio amp. Not video related, therefore no use bothering.
      U59 + U64 + all the resistors in front of them look like the video DAC. Question is: where does the SYNC pin go to? If you could backtrack that, it would be nice. IMHO it goes to U92 or U96. You might find resistors or capacitors along the way, which would be useful to know about.
      Rigols are more than fine even for not-so-easy repairs, if you decide to go for one.
      My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
    • My opinion?

      If I had to recommend the most affordable gear then I would suggest Rigol. I tried one briefly and it was very good for the price range it was advertised at. There are relatively cheap USB-based scopes around: stay absolutely away from them. Usually, you can afford a proper scope for the same price. Be aware however, that sometimes quite nice deals appear on eBay for "obsolete" tools that are still very useful and friendly. Old Philips, HP and Yokogawa CRT based scopes with digital memory still pack quite a punch if you can forgo on today's luxuries. Expecially because old scopes, no matter the brand, don't run Windows!!

      As for my experience I have tried all the big players so far: Tektronix, LeCroy, HP/Agilent/Keysight/whatevernametheyregonnachoosetomorrow and even briefly used a Rohde&Schwarz. The low price range from Tektronix is basically toys. Expecially the monochrome ones; stay away! LeCroy is very useful and complete but I hate their pots as all of their scopes are suffering from what I call "the jumping pot syndrom" which makes me want to throw the instrument outside of the window. Keysight is the product I would really buy, provided money was not an issue (not that the others are any cheaper).

      As for characteristics:

      - 2 channels are absolutely a must, but 4 is _way_ better
      - trigger in and trigger out ports are something you can find everywhere now; if you go for an old scope, check if they are available
      - bandwidth for arcades should be at the very least 50-100MHz

      - it is very comfortable to have a sample rate at least in the high MS/s to the low GS/s area
      - run/stop/single function is mandatory, as well as the biggest memory you can afford
      - zoom is very useful if you can afford it
      - a wide variety of triggers is very desirable, expecially the flexibly configurable ones
      My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
    • acblunden2's Rigol post beats all those posted by Mitsurugi in the same price range. The DSO1052 also is a nice machine however. ...if it only costed like $150 it would be an immediate buy. As for me, I repair arcades in the office after my shift. There I typically use a 350MHz infiniivision 3000A (if I remember the model correctly). It's quite comfortable as it also has 16 logic analyzer channels which can be freely combined with the 4 analog ones. Very versatile machine, but it goes for 12k+ euros brand new.
      My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
    • No, not surrendering. But there are few experts that would touch a KI board. The one recognized expert at arcadecup.com when he fixes this board, just announces "It's fixed!". No repair logs of any sort. Like he is guarding an ancient Chinese secret. If by donating it to you, you can dissect all you want and pass the info on.

      It does however sound simple. Especially, since the board functions. I will give it a go for sure. But if I ever donate it, it would go to you with the hope you unravel those ancient Chinese secrets. This game was not ported faithfully to a console until recently. Donating it would save one of these somewhat hard to come by boards that are in need of repair from going to the scrap heap.

      I won't be able to look at this again for another week as I travel Mon-Fri for work and this weekend, I am taking a road trip to trade one of my cabs for another. Report back then.