Foam And Antistatic Bag Bring Vintage Compaq Keyboard Back To Life

After winning an online auction for an 1980s vintage Compaq Portable PC, [leadacid44] discovered why it only cost him $5USD – the keyboard was shot. Not willing to accept having forked out $45USD to ship a brick, he tore into the ancient machine and came up with a found-material solution to the wonky keyboard.

[leadacid44]’s very detailed writeup of the fix for his Compaq includes a thorough examination of the guts of the machine. He got it to boot to MS-DOS 5.0 off of a 20MB ISA hard drive card and began probing the keyboard problem. It turns out the Compaq keyboard has much in common with a modern touchscreen, in that it’s a capacitive keyboard. Unfortunately the foam disks used as springs under each key cap had degraded over the last 30 years, so [leadacid44] began a quest to replace them. After much experimentation and a few false starts, he created a sandwich of transparency film, closed-cell polyethylene foam, and a Mylar antistatic bag. Many discs were punched out with a leather punch and tediously placed in the body of each key switch, and the quick brown fox was soon jumping flawlessly over the lazy dog.

We’ve seen some fixes to these lovable luggables before, like this dumpster queen that became a Hackaday Retro submission. At least [leadacid44]s machine didn’t release the Magic Blue Smoke like that one did.

19 thoughts on “Foam And Antistatic Bag Bring Vintage Compaq Keyboard Back To Life

  1. add to the list of machines having a keytronics system: DEC computers and terminals in the 70’s and early 80’s, tektronix 4002a, Apple Lisa, Holborn computers. etc. etc. we used foam of 5mm thick and the bag of a bag of chips here in The Netherlands. doublesided tape, and a holepunch of 11mm did the rest. we reused the plastic disks from the old pads as they are a little bit bigger than the 11mm pipe used in a “metric country”

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  2. This is more of a ‘restoration’ than a ‘repair’. Good job though. The unusual form factor would make it a collectors item.

    The 80’s … when everything was made by BRICK Inc.

    I can’t place the exact era. I think it’s an IBM XT clone with an equivalent 5MHz 8088 CPU. There were old keyboards from that era that had a ‘XT’ ‘AT’ switch on the bottom that would be useful as a backup.

    The XT keyboard followed the key-mapping of the IBM PC Junior and the IBM AT clone had a different key mapping that is still in use today. Apart from the key-map I think the key-up (release) was handled differently. I might have some of this wrong as it’s all a bit vague now.

    In any case the protocols are well documented so you could get any old keyboard to work by replacing the micro-controller.

  3. Ha, I used and one of those luggables back in the day (86, I think). Used to skateboard to and from work with it. I can still “feel” the weird dynamics of skating with something that heavy dangling from my shoulder.

    The weirdest thing about it was that it didn’t seem that weird at the time ..

  4. FYI, This is MIGHT applicable to the little bit of foam that is/was inside the 8-track audio tapes.

    The foam would turn breakdown into a hydrocarbon sluggy tar/resin even if stored in cool,dark place. Kinda looks like the 8-track tapes had some sort of brown minor nose bleed.

  5. I fixed one of these a few months back too. I ended up conformally coating the entire keyboard PCB and using punched mylar disks glued to foam sheets (similar to leadacid44’s approach) under each key. Even through the mylar disks were plastic side down, I found the edge of the disk would short out the capacitive pad unless I used an additional insulator, hence the conformal coating. It does make for the most awesome retro serial terminal imaginable.

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