Once again, your host NCommander has taken off on another crazy and/or insane project for dubious game. In this case, working to revive one of the worst pieces of vintage tech: a Key Tronics foam and foil based designed that was, unfortunately, used with my Compaq Portable 1.
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Blog: casadevall.pro
Items used in this video:
Key Tronics Keyboard Repair Kit: texelec.com/product/foam-capa...
Interesting Timestamps:
00:00 - Intro
01:00 - The Foam and Failure Keyboard
02:19 - Recap
02:42 - POST Codes
03:28 - Deep Cleaning
05:15 - Floppy Drive Inspection and Testing
10:40 - Keyboard Inspection and Teardown
13:50 - Compaq Portable KB Signaling
15:20 - Advanced Keyboard Troubleshooting and Repair
17:10 - Keyboard Testing and Reassembly
17:52 - The Road Forward
18:46 - Typing Demostration
After getting our first successful power-on last time, I continued on the process of trying to revive this Compaq Portable 1, and slowly tease out a successful boot from it. While the largest amount of failure was in the Key Tronics keyboard, I had other hassles I had to climb to get my first working boot.
Because there is no built in hard drive, I needed to get a booting system via a floppy drive, something complicated by the fact that the floppy disk controller on this system only supports low-destiny 360k disks. However, what I learned is a regular 3.5" drive will work just fine, as long as I limit it to 3.5" disks only.
In examining the dead disk drive, I learned that both drives had seized heads, and appear to have fried belts. I used my SuperCard Pro to run drive diagnostics, but for the moment, both seem entirely dead. I did manage to tease some life out of one of the drives with the SuperCard Pro board, but without replacement belts, it seems a lost cause for now.
However, with my copy of IBM PC DOS 3.3, I was able to get the Compaq to boot to a time/date prompt, just to discover that the keyboard was entirely dead. This began the worst part of this project, by far.
Quite a few other vintage KZfaqrs such as 8-Bit Guy have tackled the Compaq Portable, but none have given this keyboard the autopsy that this KB deserved. Foam and foil keyboards, as the name suggests, use a foam pad to determine if a key has been pressed. After 30 or so years, the foam layer had fallen apart (which is basically the most common reason on why these keyboards fail). Repair kits exist to repair (or well replace) the keyboard foam layer exist, and I spent several hours of my life going through and replacing these foam pads.
However, even after doing so, the keyboard didn't work, and combined with horror key feel and just general cheapness, the keyboard was just not pleasant to use. Afterwards, I found that the keyboard faults were due to a break in the keyboard connector wire, and after taking another dive with the Sams schematics, learned that the hardware design team at Compaq, at some point took total leave of their senses.
After wiring a bodge to deal with the broken ground line, I was able to get the keyboard working, and even was able to load Epxy Rogue, showing that basic functionality does appear to be OK!. I still have a lot to do with this, but it's a one step at a time sorta project.
Music used under license from Epidemic Sound.
#Compaq #RetroComputing #MechanicalKeyboard#FoamAndFoil