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Kaga Denshi KZ-20EN Tube with Aunix PEIC31083 Chassis

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  • Kaga Denshi KZ-20EN Tube with Aunix PEIC31083 Chassis

    Hi All,
    I'm new to this forum and I am repairing a cocktail arcade table with Kaga Denshi KZ-20EN Tube with Aunix PEIC-31083 Chassis for a mate.
    Originally the unit would display some red elements and you could just make out the title screen.

    Assuming the unit is at least 20-30 years old I changed all the electrolytic caps on the chassis with new ones.

    I plugged it all back in and the picture was about the same, I gave it a break for a few days and tried it again, now no picture at all.

    I tried posting pictures but can't seem to, unsure why, I have used the url linking thingy instead

    I'm assuming flyback transformer but not real sure as I have little CRT experience or a schematic.

    I'm on Brisbane northside if anybody is interested in helping.
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    Edit: screen is below.
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    Last edited by nightdude; 26th August 2019, 03:02 PM.

  • #2
    Hmmm, IIRC the KZ-20EN is the same thing as the Sega MC-2000S. That's really the chassis designation, so there would normally be another sticker on the tube, maybe from Mitsubishi or Hitachi. If that's right, this means the chassis has been swapped at some point, probably with a cheaper one, and the schematics for the MC-2000S won't be any use to you.

    Safest and best thing is to get in contact with [MENTION=204]Jomac[/MENTION] in Perth. He'll ask you a few questions, and if he can fix it, it'll probably come in under $200 including postage.

    If you want to give it a crack yourself... Make sure you only run the monitor with the tube and chassis all plugged together. Video input is helpful as well. What happens when you turn the brightness knob all the way up? If nothing, can you find the screen control? It's normally one of the two knobs on the flyback, the other being focus, but sometimes it's elsewhere on older chassis. Might be a pot on the neckboard. This is like a master brightness control, and if you slowly turn it up while the set is running, at this point you'll be hoping to see... something, even if that means a dull grey screen. Stop if you hear any arcing. Take some photos if you can

    EDIT: And remember to be careful around live equipment! There are kilovolts across various points, and that screen control might have 600V over it, so keep unwanted fingers away, wear rubber shoes, use well insulated screwdrivers, etc. I'm assuming you've worked out how to discharge the tube, and that's important too. An old tube might bleed charge for a few days, so discharge every ten minutes before handling.

    Comment


    • #3
      Welcome to the forum , probably best to have a look over this thread and as you will see what you have is exactly what I refer to in that thread.
      http://www.aussiearcade.com.au/showt.../9261-Cap-Kits

      The tube you have is the best 20" arcade tube ever made , I have never seen one fail yet unless of course someone has got a bit carried with a rejuvenator , The original chassis were also "A" class except many have failed due to burning , corrosion or exploded flybacks which is more than likely why that has been matched up to a PEIC chassis because despite being lower quality they were perfectly compatible but not common in Australia.
      I haven't seen any of these with dead flybacks , if it is then it's history so fingers crossed that's not the issue , it most definitely would not have been the cause of the original problem.
      Having read the above thread you will see I don't like working on anything people have messed with and failed, it makes the job so much harder than if left alone but if you want to send it over I'll assess it and if not repairable due to (dead flyback or bad physical damage) there is no charge , I only ever charge for things I repair so not much to lose sending it over.

      Comment


      • #4
        Thanks Jomac and Buttersoft.

        Comment


        • #5
          Hi All,
          Just an update for you. I sent Jomac my chassis, only for him to find there was nothing wrong with it.
          So back to the drawing board.

          Today I re-checked all the power supply voltages and they are +5v= 5.8 , -5v= -5.8, 12v= 14.7
          the 110v is 105V

          Jomac mentioned that I should be getting music or sound when power is applied, all I am getting is a "pop". I measured 4.8v across the power pins on some of the chips on one of the boards.
          There is 5.8 and 14.7V going into the board.

          Unsure of where to go next.

          Comment


          • #6
            Go back to my post above, and if that doesn't help, let's talk video sources - what are you plugging into the chassis, an original old game board? A multiboard? Do you have any other video sources you might try?

            Comment


            • #7
              If the tube and chassis are fine, all that's left is the PSU, wiring and game board.
              I'd be checking your wiring and connector next. 1V drop is a big drop for a standard board. That, and missing colours could be your connector. It could also be the board, but I'm assuming you've tried several game boards already?

              Comment


              • #8
                I've tried all 6 game boards I have, all with the same results.
                So I have a power supply I can try and I'll buzz out all the wiring.

                - - - Updated - - -

                Hi Buttersoft,
                Jomac says I have a sync problem, but after looking into it more, the game boards don't seem to be outputting any signal either audio or video.
                I've tried all the game boards I have with the same result, so i doubt I have 6 faulty boards. Will check wiring and PSU next.
                I unfortunately don't have any other video sources.

                Comment


                • #9
                  Yer audio and video both missing probably means the power supply in the cab is dicky.

                  Comment


                  • #10
                    Hi All,
                    Update with a sheepish look on my face.
                    After receiving back the CRT chassis from Jomac, I tried powering the unit up without the chassis in to see if there was sound.
                    There was none (see my last post). Today I tried a new power supply with the same results.
                    Again Jomac to the rescue, he suggested the sound was turned off unless the game was actually being played.

                    I re-plugged in the chassis and turned it on. Game came up with nice colours (Thanks Jomac).

                    I tried playing the game but couldn't get it to start, so I tested all the switches and found the start switch to be faulty. I've rigged up a new switch.
                    Lets play!
                    Thanks to all who replied!!!!

                    Comment


                    • #11
                      Originally posted by nightdude View Post
                      Hi All,
                      Update with a sheepish look on my face.
                      After receiving back the CRT chassis from Jomac, I tried powering the unit up without the chassis in to see if there was sound.
                      There was none (see my last post). Today I tried a new power supply with the same results.
                      Again Jomac to the rescue, he suggested the sound was turned off unless the game was actually being played.

                      I re-plugged in the chassis and turned it on. Game came up with nice colours (Thanks Jomac).

                      I tried playing the game but couldn't get it to start, so I tested all the switches and found the start switch to be faulty. I've rigged up a new switch.
                      Lets play!
                      Thanks to all who replied!!!!
                      Well looks like I celebrated too early. The screen has gone blank again. Time to check all wiring and connections.

                      Comment


                      • #12
                        Anybody willing to test a few games I have on their machine?
                        I live Brisbane northside

                        Comment


                        • #13
                          Another update.
                          Looks like the power supply had dodgy capacitors, so I replaced those, now the voltages are correct.
                          I can get one game playable pengo packman, seems to work OK for 5-20 minutes then the screen very slowly starts to fade away, I'm thinking the tube is faulty.
                          I tried a new meanwell power supply too.
                          I wired up a 60in1 in parallel with the original wiring (obviously disconnected/unplugged the original game first) and the games all work and display for the same time as above.
                          So I've connected up an LCD screen without any issues and display doesn't fade.

                          Comment


                          • #14
                            Fading away could be caused by a number of things. I'd start with the brightness pot. It might be heating up and losing contact.

                            Comment


                            • #15
                              Most of the time this is caused by the neck board not being pushed all the way on, as soon as the heater pins get warm the pictures fades away.

                              Comment

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