Kaypro 2X Back (almost) to Normal after 30 Years

After a fun-filled weekend, my old Kaypro 2X is back on the air -- sort of. The Micrex video board was re-capped and that seemed to have resolved the problem. At that point, I was a little disappointed that my quest was so easily fulfilled. It was a real no-brainer to buy some capacitors, wick out the old ones and replace them, turn it on and view the results. Moderately plain sailing.

Or so I thought.

Anyway, by way of passing on what I'd learned here's a summary of some notes I made to help others traveling along this road. Below are the initial pictures that tell the tale:

Bad K2X Display Symptoms

Captioned Micrex TW-105 94V-0 Board

Final "Semi-Fixed" Display

List of Micrex Board Electrolytic Caps

As I said, it did not turn out to be as smooth a journey as I thought it would be. After routine checkout on the bench, the reassembly turned into a nightmare. The disk drives would not boot, not spin, and and generally became non-responsive. I did a little snooping around the board and found that all the chips had the proper Vdd (+5V), the power connector yielded the proper voltages to the main board (-11V, +12V, +5V) and the drives.

I even checked a couple of signals on the board:

1 MHz Signal at pins 2, 4, and 5 of U65

2.0 MHz signal at pin 13 of u65

These weren't the only signals I scarpered. Just too busy head scratching and trouble-shooting to make a proper documentary suite of it. When things get squared away, I will revisit this and do shots for a good machine as a reference for any others wishing to revive Kaypros. (You listening, Vintage Computer moderators?)

Eventually, I determined all was working on the main board and, after testing the floppy ribbon cable and connectors, wiped down the floppy edge connector with a Q-tip and alcohol. Seems to have worked because the old girl sprang to life and booted!

I still have two problems with the video, however. (1) It's not centered vertically and (2) It's a little skewed on the bottom (see below). It may be due the the fact that I did not replace the 4.7 uF non-polarized cap; the guy at the store pulled a weensie polarized one when I was not paying attention. So, I'll get a proper cap for that and see what it does.

Wavy Gravy at work on the bottom quarter of the screen

But the vertical thing has got me buggered. There is only a "V SIZE" (V405) control and a "V LIN" control (V410) and right now, the "V SIZE" is at full throttle. The instructions in the Kapro technical manual (Jun 1985 edition) says this:

I was pretty tired Sunday afternoon but I seem to remember doing just that only it did not seem to yield the desired results. I may not have gone back and did a "dip the plate, peak the load" procedure (just like my old TS-830s) ao I'll tinker with it some more and see it that fixes it.

Another matter that needs resolution is the keyboard jack. My old one fractured and I was casting about for a replacement scheme. I had seen some folks' kluges on the Internet -- one literally looked as though the guy chewed up a wad of Double Bubble and used that to join the broken cable to the plug. (I still do not comprehend folks restoring stuff like this who will not make a proper investment in a solder station and associated education in the skill.)

I ran this by my wizard friend, John, "the knower of all things", and he pointed out a similar part to the shredded female jack in the picture above. Finally tracked it down at Digikey who got it out to me right away. I will Hoover up the order and PN info and add it if I do a post on the keyboard repair job.

Until then, it's back to the UW project and twiddling the video board pots to see if I can exorcise Wavy Gravy.

Peace!