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Color Computer 1 motherboard revisions?

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    Color Computer 1 motherboard revisions?

    i have a coco 1 that i picked up from the goodwill bins a while back. i tested it, it powers/relay clicks, but i get no video output.

    I found the coco 1 service manual and the coco 1 sams manual, but the depicted motherboard layout is different. components are also numbered differently.

    is there a way to identify which board i have? it is 16k with 64k jumper/option, but no 4k markings on the board. see picture attached. and are there alternative service manuals/schematics for various revisions?

    Attached Files

    That's a Paul T Schreiber "cost reduced" Coco 1 board, which is a 16K/64K board sold in the 26-3002A, 26-3003A and 26-3004 silver cocos (centered nameplate and no Ram size badge), as well as the 64K Coco 1 (26-3003B).

    It doesn't connect to any video output, only a television set via the RF in, and then you need to tune the TV.

    These boards are also colloquially known as the 'F' board or '285' board.

    To test it would being connected to a TV turn it on and type MOTORON, and listen for a click from the cassette relay, then type MOTOROFF and listen for another click from the cassette relay.

    Hope this helps,

    *There is never a charge for Tech Support even if you don't purchase from me - We are Enthusiasts Helping Other Enthusiast and that is just the way it is


      Originally posted by TRS-Ian View Post
      That's a Paul T Schreiber "cost reduced" Coco 1 board, which is a 16K/64K board sold in the 26-3002A, 26-3003A and 26-3004 silver cocos (centered nameplate and no Ram size badge), as well as the 64K Coco 1 (26-3003B).

      It doesn't connect to any video output, only a television set via the RF in, and then you need to tune the TV.
      thanks Ian. very helpful.

      I have a tv with tuner that i use to test other RF out devices, and i'm getting nothing.

      regarding voltages, the other coco 1 service manual references +/-5 and 12. the test points are different on this one, but i'm seeing some +/-24 volts and +/-5. also at the RAM chips i'm not getting voltages on pins 8/9 as referenced in the troubleshooting section, but i do get the pin 1 voltages.

      i'll keep looking for the proper manual for this revision.


        broken RF jack. This machine works fine now.

        coco1 rf out Screen Shot 2019-01-19 at 6.37.17 AM.jpgcoco1 screen Screen Shot 2019-01-19 at 6.38.56 AM.jpg


          That'll do it... good save.