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Convert old CRT to VGA using GBS8200


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  • Convert old CRT to VGA using GBS8200

    Hi to all,
    someone please can help me to adapt the output monitor CGA/RGB signal to the GBS8200?
    I understand that the GBS accepts analog signals while the system outputs digital signals .. correct?
    So i cannot connect the (RGB GND H V) from 9din output directly to the GBS8200.
    Is correct? anyone can help please?
    Thanks a lot in advance

  • #2
    I do not have the exact data on the GBS8200 conversion board, but what I can help with is the Steltronic lane computer (Elex and Super Elex) both of these have an RGB output. The diagram of the output connections of the Steltronic Elex and Super Elex is attached in the drawing.

    The drawing shows DB9 Male pins for a cable that would connect to the Steltronic Elex or Super Elex.
    For reference, the Elex and Super Elex have a DB9 female socket connection for the RGB signal.

    Jim Osdale
    Steltronic automatic scoring
    Jim Osdale
    Steltronic USA


    • #3
      Thanks a lot Jim for reply!
      i know the scheme of rgb output (i see that following the input on the crt chassis)
      the problem is that I connected the input on the gbs (both in rgbhv and rgb mode) but I see very very bad image on new vga lcd)
      so can be that the gbs not accept directly this kind of input?
      Can be that I need to pre-convert before pass to gbs?
      Can I convert the output to scart and then pass to gbs?
      what you suggest to do?
      i attach the manual url of the gbs if needed
      thanks al lot!!


      • #4
        Hi again,
        no one have advices about?
        Can be that this circuit save me?

        After i can pass composite sync to the GBS?
        What you think about?


        • #5

          I'm sorry but I do not have specifics on the converter board you are trying to use. Even if I have the manual, it's not going to work because the outputs of the Super Elex must match the inputs of the board you are trying to use.

          The Elex and Super Elex have specialized outputs that were designed for CRT monitors. Additionally, they were multi-sync meaning they would work on monitors that were designed for NTSC and PAL.

          Horizontal freq = 15625Hz ( Fclk / 1728 )
          Vertical freq = 50.08Hz ( Horizontal freq / 312 )

          Steltronic located in California has a converter that we sell that is made specifically for the Elex and the Super Elex to work on the new flat screen monitors.
          The price is $287.00 per monitor.
          You can order parts at this number here: (909) 971-9656

          Jim Osdale

          Jim Osdale
          Steltronic USA


          • #6
            It looks like it should work based on what you posted. What kind of picture are you getting. How are you making the connection to your new board?


            • #7
              Thanks for interest with my problem exMech.
              Anyway i'm preparing the sync mixer to connect between input signals and GBS8200 (as normal csync signal), you think that works? have you already tried something like that?
              I not tested yet 'cause the place where the super-elex computer is located is very inconvenient prohibitive place! (anyway this weekend i will do the test).
              I attach here the "best" image that i have if i connect the input directly to the GBS8200. What you think about?
              Thanks again!
              Attached Files


              • #8
                I don't have experience with your board so I can only help based on the information you provided. You didn't say how you are connecting the two systems together. The picture in your documentation shows an RGBHV connector in the lower left corner of the image. Is this a 15 pin or a 9 pin connector?


                • #9
         i did a little research in to your board and everything you need is in the datasheet you provided. This along with what Jim posted should get you going. You should have an 8 conductor cable included with your board. This should be similar to the white 5 conductor one shown in the picture on the datasheet. This will plug into the white 8 pin connector just above the 15 pin RGBHV connector I mentioned earlier. These are in the lower left hand corner of the board looking at the picture. These two connectors are tied together so it doesn't matter which one you use. Just to the right of the white connector you should see P11. Just to the right of that is the pin out for the connector. If you find these you have the correct connector.

                  On the lower right corner of the datasheet you provided is the wiring for the 8 conductor plug. I've put a screenshot of this below. This should match the layout of the pin out on the board. Take the red wire from your harness and connect it to the red wire shown in Jim's pin out. You may need to use a DB9 connector or if its a female connector your connecting to you can push the wires into the sockets for testing purposes. Then do the same thing for the remaining wires following Jim's pin out and the one below.

                  Once everything is connected, plug the connector into the board. Now follow the remaining steps in the instructions starting at step 3.

                  Apparently it is very important to use a power supply of at least 2 amps or you may get a strange output.

                  This may take a little tweaking so post back if you need further help. Let us know how it goes.
                  Attached Files


                  • #10
                    Very very thanks for your patience to help exMech;
                    So i take directly the input from CRT (R/G/B/H Sync/V Sync/GND) from the back of the CRT Monitor Chassis where they are clearly specified with their own typing so i think i cannot mistake ..

                    Trust me exMech, before ask help here on this forum i do many many many attempts trying to connect directly input to GBS8200 (including what you kindly specified the 6 wires to P11).
                    Sure i used 2A 5V power supply!
                    So can be that the problem is that the 2 syncs are "incompatible" if directly connected to the GBS ..
                    After search about similar problem with GBS i have found that the AtariST have a similar problem connecting to the GBS .. on the web there are many solutions about .
                    My hope was that someone had already solved this same problem of mine!

                    But exactly the output of the super-elex is?
                    CGA as Jim Osdale tells with: Horizontal freq = 15625Hz ( Fclk / 1728 ) Vertical freq = 50.08Hz ( Horizontal freq / 312 )
                    as i can see i not find this accepted input on the GBS manual, correct?

                    thanks a lot for help!!


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