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Thread: Victory! Sol-20 repair

  1. #1

    Default Victory! Sol-20 repair

    I had to share a hard-won victory getting this Sol-20 up and running. I'll post repair notes to my site soon. It involved a few iterations of power supply, PC board, and keyboard troubleshooting.

    Next up is refurbishing the keyboard, a topic of much discussion on the board. I'm planning to punch out my own foam pads and was wondering what recommendations were out there for particular foam products? What thickness and foam density work best? I was going to try a lighter weather-seal type foam. Also: the keyboard is the type without the pad clips and the foam inserts are held in with an adhesive membrane.

    IMG_1148.jpg

  2. #2
    Join Date
    Dec 2011
    Location
    East Coast USA
    Posts
    590

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    Use low density foam or it won’t feel right. I found only one package/thickness of this foam at Home Depot and not all carry it. I use space blanket material from Walmart. One blanket is enough for many keyboards. Then use permanent double sided tape or contact cement to attach it to the plastic sheets to make the circles, which you can buy uncut sheets from a hobby store. Then you punch it all out together. I don’t remember the exact thickness of the plastic, but if you look at a current disk and then go to the store it should be obvious.

  3. #3

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    Congrats! I'll be very interested in what the power supply needed (and where you found replacement caps, if any).

  4. #4

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    Quote Originally Posted by DaveL View Post
    Congrats! I'll be very interested in what the power supply needed (and where you found replacement caps, if any).
    I ended up replacing Q1 and Q2, the Darlington pair on the 5V line and the MC1458P op amp that is part of the regulator circuit. Caps seem to be fine and powered it all up initially with a variac. Oh, and I needed to replace the fuse holder, but Littel still manufactures the same fuse block.
    Last edited by ef1j91; November 20th, 2017 at 02:15 PM. Reason: pesky typo

  5. #5
    Join Date
    Nov 2012
    Location
    Richmond Hill, Ontario, Canada
    Posts
    884

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    Quote Originally Posted by Corey986 View Post
    Use low density foam or it won’t feel right. I found only one package/thickness of this foam at Home Depot and not all carry it. I use space blanket material from Walmart. One blanket is enough for many keyboards. Then use permanent double sided tape or contact cement to attach it to the plastic sheets to make the circles, which you can buy uncut sheets from a hobby store. Then you punch it all out together. I don’t remember the exact thickness of the plastic, but if you look at a current disk and then go to the store it should be obvious.
    Just to give some more ideas...

    I used weather stripping that was of good consistency. This already had one side sticky. I stuck that side to shiny wrapping paper from the dollar store. I then used two sided tape on the foam side and used overhead transparency sheets for the plastic disks to make the the rigid side that fit into the key switches. I punched the plastic disks separately but did everything else including the two sided tape with one shot. That worked out for me.

  6. #6

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    Congratulations! I've gotten my SOL-20 working-ish, but my first attempt at rebuilding the keyboard didn't work. Maybe I'll get around to trying again over the holidays?

  7. #7
    Join Date
    Dec 2011
    Location
    East Coast USA
    Posts
    590

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    Quote Originally Posted by ef1j91 View Post
    I ended up replacing Q1 and Q2, the Darlington pair on the 5V line and the MC1458P op amp that is part of the regulator circuit. Caps seem to be fine and powered it all up initially with a variac. Oh, and I needed to replace the fuse holder, but Littel still manufactures the same fuse block.
    Post the part number for the fuse holder. I’d like to order some spares.

    Thanks,
    Corey

  8. #8

    Default

    Quote Originally Posted by Corey986 View Post
    Post the part number for the fuse holder. I’d like to order some spares.

    Thanks,
    Corey
    Jameco part no.: 1711701
    Manufacturer: Littelfuse
    Manufacturer no.: 03420038H

    http://www.littelfuse.com/~/media/el...asheet.pdf.pdf

  9. #9

  10. #10
    Join Date
    Jan 2011
    Location
    Vancouver, BC
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    2,393
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    Question.. I am looking around for 'space blankets' here in town to get my keyboard repaired.. none are made from mylar... they all appear to be aluminized something or other now.. will that work? Or does it have to be mylar?

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