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    Sord M5 repair

    So a while back I landed myself a Sord M5. They're a cute little computer that uses the same TI99xx graphics chip found in the vast majority of 80s consoles & computers (Coleco, Sega SG1000/SC3000, TI99/4A, Memorex MTC, MSX etc etc). While launched in Japan, they did see a wider global release but ultimately suffered the same fate as so many other early 80s computers - existing when the Commodore 64/MSX/ZX Spectrum were booming.
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    (and no, it's not yellowed. that's just how they came!)

    While this one came with a bunch of games, it was missing three things: Joysticks, the cover that goes over the top half of the Sord, and a PSU. While the cover is probably nigh on impossible to find, the PSU (and later on, the joystick situation) is something I can definitely deal with sooner.

    Problem is there's not a lot of info out there like the other popular systems of the era, however thankfully a local friend has a complete M5 including the PSU that I could check to see what voltages it put out. The Sord uses a 6 pin DIN plug, with pins 1/2 being Ground, pins 3/6 +5v, pin 5 -12v, and pin 4 +12v. Something all PC power supplies will happily provide, but I settled on a spare AT PSU I had here.

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    The second image is a partial (?) schematic for the Power Brick that shipped with ​​the Sord M5 that I managed to find on archive.org. The pinout there is for the DIN plug coming from the PSU, not the connector at the computer end, something I nearly learnt the hard way!

    After getting the wiring right and connected, was time to test it out:
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    Success! All that's left to do for the PSU is to get out the hot air gun to shrink the wrap on each pin, then assemble the DIN plug. Will also tidy up the excess PC leads & do something with the power switch - although given these are super common voltages, I may look around for an alternative supply that isn't so huge!

    Next steps: Sort out the controller situation & figure out why the sound doesn't work.
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    Last edited by darkjedi; 14 May 2020, 12:37 AM. Reason: NUked the incorrect controller info link!

    #2
    So the sound and controller somewhat go hand in hand. Given the keyboard connects using tinned wires as opposed to a ribbon cable I was fairly against needlessly plugging it in/taking it out.

    The Sord M5 uses a SN76489, another fairly common sound chip of the day. Heads out of Pin7 to the via marked on the left. Then travels north to C2 - the 22uF capacitor I've circled up top. From there, it leads straight to the RCA plug. Not normally one to play cap shotgun, but in this case decided it was worth it all the same. Glad I did, as the cap had evidence of leakage on the pins after I replaced it!

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    With that being all I can do for now, changed my focus to getting a controller to work. The adapter I mentioned before was a bust, as managed to find the creator on Twitter who said he'd never been able to make it work and instead converted an old PC controller he had to work with it instead. With a shed full of partially working/broken controllers, seemed like an easy choice. Ultimately settled on a NES pad, combined with a spare DB9 joystick lead that had 6 wires in it - the exact number needed for the Sord M5 controller!
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    So the Sord M5 has 6 outputs on each joystick/joypad, with the directions having a shared common pin, and fire buttons also having their own shared common pin. Each fire button also shares a pin out with a direction, with diodes on the fire common to make it all work. Excuse my utterly untechnical sketch, but the internals look something like this (pinout on the right is the joystick connector looking at the back of the Sord):

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    Rather than hack up a NES controller on a whim, dug out a breadboard kit I had here from something ages back but had never used. The minimum to start a game would require me to hook up Pins 3, 5 and 6 (Right/FBA, Direction common & Fire common). First time I’ve used a breadboard, so learning new things was fun! Top button is FBA, bottom is RIGHT. Yellow lead goes to fire common, black at the bottom is direction common. I'm unsure on the minimum values of the diodes, but I had some 1N914 on hand, so I used those!)
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    And what do you know? Not only did the control setup work, but the cap was the cause of my sound issue!


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      #3
      Last step was to get the NES pad hacked up and turned into a Sord controller. I used this thread from Atariage for guidance on how to turn the NES pad into an Atari 2600/7800 pad. Based on that, and needing to find a spot to run both diodes + link the fire buttons to their respective direction pin, I poked around with MSPaint until I figured out a rough sketch of how I'd run things - With this as my final plan:
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      Based on the above thread I cut the tracks to the discrete resistors the NES pad uses, and also (which isn't drawn in above) cut the common trace directly above the UP pad to separate the controls from the fire buttons. Both diodes were mounted on the reverse of the PCB, with some kynar to link the fire buttons to their respective leads. End product wasn't too bad, but most importantly: It worked!
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      After putting it all back together, I hit one final snag in that the 6P mini-din connector from Jaycar was too fat on the end to fit inside the shell! Thankfully it's something a nice sharp knife could fix, with my needing to trim back the first 3-4mm of the connector shell to make it fit (original shell on the left below):
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      While I'd like to find an original joystick or two, they're much like the Intellivision and TI99/4A controllers - as in, utter garbage! (and also horrifically expensive, like most things Sord related). Would also like to find a smaller PSU to retrofit for use. The voltages the Sord M5 uses are pretty common, so it shouldn't be *too* hard to find something down the line. For now I'll take some time to tidy up the power supply and make the switch a bit safer to use, but for now I'm just happy it's all working!
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        #4
        Few resources I found while working on this that could be handy too:

        Commodore pages (original idea to convert an existing controller)
        AtariAge - NES Control Pad Conversion FAQ (the guide on using a NES pad with a 2600/7800)
        Link (lots of Sord M5 stuff. Is in Czech, mostly because the system saw a lot of popularity there!)
        Sord M5 stuff (random M5 ROM stuff)
        Google Groups (Links to where I pulled the NTSC & PAL schematics for the system from)

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          #5
          Had a bit of a bash tonight as I work through the games on the M5 Multicart. Some decent titles, also some utter stinkers in there!

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            #6
            Poking around the EasyEDA editor and threw this together. Looks a little cleaner than my pencil line work

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            Wonder if there's any way to make an adapter to use a NeoGeo joystick or something similar? The two separate commons makes that a lot trickier than my simple-ass brain knows how to handle though.

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              #7
              Thanks for the diagram. I used it to wire up a Sega Genesis controller to the Sord M5.

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                #8
                Originally posted by Rastersoft View Post
                Thanks for the diagram. I used it to wire up a Sega Genesis controller to the Sord M5.
                Glad I could help. Enjoy the Sord!

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