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Sega CD 1 Repair

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  • #16
    The non-working NeoNeo wasn't getting anything displayed on screen at all, and the drive made a horrid noise at least one of the times I tried to power it on. It doesn't look like it was mistreated, but I reckon it'd have to be a few issues that are pretty serious. The only reason I say 'serious' though is because it was like that when I got it. The MCD was working and then nothing at all, so at least I knew the CD drive was fine.

    Really hope you can get that NGCD working as well though AK. Would be cool to get two classic machines back from the dead and in Aussie!

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    • #17
      Yeah once I get a 240v PSU or step down I'll have a look at it.

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      • #18
        Bump this old thread !

        I have the very first shot of a japanese Mega-CD 1. But one day without any reason it stop working.

        After long search, I did not find where is the failure. When I powering up the Genesis I have a blank screen, however the tray start to close (when it's open). No BIOS screen, no sound.

        - All fuses are OK
        - power\sound board works (I tested it on another MCD)
        - the BIOS works to.

        The issue may come from the interface board between Genesis and Mega-CD. It use a cable plug directly on a crystal oscillator on the MCD motherboard.
        But I can't test the motherboard on another MCD because interface board for this model is specific.

        I took some pics for understanding :

        The motherboard parts side
        The motherboard solder side
        MB Memory chips
        crystal oscillator sub board
        sub board connector
        interface board part side
        interface board solder side
        closer view of interface board's chips
        closer view of solder side + grey cable
        closer view of solder side + black cable

        It would be nice if someone can save this first release of this Mega-CD. Plus, his BIOS is not zoned. It works on both 50Hz and 60Hz Genesis.

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        • #19
          Originally posted by Dr.Wily View Post
          Bump this old thread !

          I have the very first shot of a japanese Mega-CD 1. But one day without any reason it stop working.

          After long search, I did not find where is the failure. When I powering up the Genesis I have a blank screen, however the tray start to close (when it's open). No BIOS screen, no sound.

          - All fuses are OK
          - power\sound board works (I tested it on another MCD)
          - the BIOS works to.

          The issue may come from the interface board between Genesis and Mega-CD. It use a cable plug directly on a crystal oscillator on the MCD motherboard.
          But I can't test the motherboard on another MCD because interface board for this model is specific.

          I took some pics for understanding :

          The motherboard parts side
          The motherboard solder side
          MB Memory chips
          crystal oscillator sub board
          sub board connector
          interface board part side
          interface board solder side
          closer view of interface board's chips
          closer view of solder side + grey cable
          closer view of solder side + black cable

          It would be nice if someone can save this first release of this Mega-CD. Plus, his BIOS is not zoned. It works on both 50Hz and 60Hz Genesis.
          The capacitors on the main board fail and cause this.
          •Converting Game Gears and Atari LYNX with McWill screens and Gameboy Pocket with backlight and Bivert mods
          •Sega Saturn, Dreamcast and Mega CD region free BIOS install and power supply repairs, NEO•GEO UniBIOS install, 3DO RGB and 240p mods, DIY kits available for all.
          • CPS2 and NEO•GEO game repairs and conversions

          Comment


          • #20
            Originally posted by Arcade King View Post
            Symptoms : Dead

            Fix: PSU/AMP board has copped some corrosion damage due to a pair of leaking 100uf 6.3 v caps at C25 and C25.
            Here a pic of the effected areas, L1 was also damage but I managed to save it.
            [ATTACH=CONFIG]28506[/ATTACH] [ATTACH=CONFIG]28507[/ATTACH] [ATTACH=CONFIG]28508[/ATTACH] [ATTACH=CONFIG]28509[/ATTACH]

            Corrosion is a prick to work on and a lot of the times what looks minor can turn out to be quiet bad.
            Replaced C24(100uf 6.3v), C25 (100uf 6.3v), C27(100uf 10v) and C26(100uf 16v) all with 100uf 25v.
            C24 and C25 both leaked and caused track damage.
            Replaced UPC2405 with new 7805 5v 1 amp regulator and fixed damaged tracks.
            Not very good pics.
            [ATTACH=CONFIG]28511[/ATTACH] [ATTACH=CONFIG]28512[/ATTACH] [ATTACH=CONFIG]28513[/ATTACH]

            PSU uses a PNP Darlington Transistor (2SB963) to switch on the power supply when the Megadrive is switched on. So you can work on the PSU on the bench you need to short the Emitter and Collector to power it up without the Megadrive. I simply removed the Transistor all together and shorted the pads.
            Once powered on I could see no current was flowing to the input of the regulator, I noticed power was rising VERY slowly at the TR4 transistor.
            There was a broken track from the positive side of cap C27 to the input of the regulator. When powered on the voltage would drop right down to .8 volts
            Problem turned out to be another bad track from the negative side of the 10v DC plug to ground.
            A simple jump and she fired right up with a nice strong 5V .
            [ATTACH=CONFIG]28514[/ATTACH]

            Being a Jap Mega CD this is the screen you get when hooking up to a pal console.
            [ATTACH=CONFIG]28515[/ATTACH]

            I went looking for a PAL bios to program but found this instead and sounded like its worth a shot.
            http://www.assemblergames.com/forums...ad.php?t=27562
            Anybody else tried this ? anyhoo I've burt the eu_mcd1_921027_regionfree_byteswap.bin and...
            [ATTACH=CONFIG]28516[/ATTACH]
            Don't have any games so tried one of my daughters Audio CDs and it worked ok
            [ATTACH=CONFIG]28517[/ATTACH]

            Just burnt myself a copy of Sonic CD so off to try a game, I'll then try a USA game to see if the region free bios does its job.
            I have the region free BIOS in a few Mega CD systems, works well.

            The Mega CD i have is a very early model and has a socketted BIOS chip, which made it nice and easy for testing. I added a socket to my Mega CD 2 and threw one in there as well, which worked great.
            •Converting Game Gears and Atari LYNX with McWill screens and Gameboy Pocket with backlight and Bivert mods
            •Sega Saturn, Dreamcast and Mega CD region free BIOS install and power supply repairs, NEO•GEO UniBIOS install, 3DO RGB and 240p mods, DIY kits available for all.
            • CPS2 and NEO•GEO game repairs and conversions

            Comment


            • #21
              Yeah been years since I've turned mine on but the Bios worked great.
              I downloaded a newer version awhile back, I'll have to update it however the one I installed ran very game I threw at it.

              Comment


              • #22
                Originally posted by Arcade King View Post
                Yeah been years since I've turned mine on but the Bios worked great.
                I downloaded a newer version awhile back, I'll have to update it however the one I installed ran very game I threw at it.
                I only did all this last year so mine is probably a pretty late version. I dont play much Mega CD, there is a couple great games on it though.
                •Converting Game Gears and Atari LYNX with McWill screens and Gameboy Pocket with backlight and Bivert mods
                •Sega Saturn, Dreamcast and Mega CD region free BIOS install and power supply repairs, NEO•GEO UniBIOS install, 3DO RGB and 240p mods, DIY kits available for all.
                • CPS2 and NEO•GEO game repairs and conversions

                Comment


                • #23
                  Hi,

                  I don't know if it's the right place to explain my problem. If not perhaps I can create an new thread about my issue.
                  I bought an Mega CD 1 japanese. I replaced all capacitors of the main board (twelve smd 10uf and two 100uf) and two 10uf and one 47uf located on the connection board (connection between MD and MCD). On the power board, I replaced all 100uf capacitors (three capacitors around heatsink and one on middle of the board). I have also clean all ribbons used to connect boards

                  After all this work, I have a freeze during boot. I see background image (a white cloud because my bios is an japanese one) and the bios version number. But nothing else. No flashing leds.
                  If I push on the reset button I get an black screen.

                  I don't know what to check to solve my problem. I look at the main board but I didn't see broken trace.

                  Comment

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