My latested repair story is about a Kaypro II from 1982. The Kaypro machines have such an odd numbering scheme. They used Arabic numerals and Roman numerals to refer to different computers, it is so confusing that collectors have taken to referring to them by the year of their release. The Kaypro II 82 is a different computer from the Kaypro 2 84 released two years later. There is so much confusion caused by this so many articles online contain inaccuracies in describing the features and functions of the machines.
I've had a Kaypro 2 84 for several years, and acquired a Kaypro 1 from 1986 last year, but I've long wanted a Kaypro II 82 both for historical reasons, because it's the first of an iconic line of CP/M computers, and also for nostalgic reasons because my uncle who bought me my first computer bought one of these machines for my Grandpa and Grandma. I knew from day one that Grandpa and Grandma's machine was a much more serious tool than the one that I had, and I thought it has an amazing design, it looked like a "real computer".
This Kaypro II 82 came from Free Geek Twin Cities via my friend Chris Gallaty. Special thanks to Chris for getting this machine when he did and for passing it on to me. The machine came with a note "Powers On - Keyboard Cable Needs Simple Repair". One of the basic rules of troubleshooting is that you should not take other people's troubleshooting work at face value, you always want to do that work yourself, but I was hopeful that the label was correct.
The plug on the keyboard port had been smashed in and that repair did need to be done so I started out with the obvious repair first. Chris has also given me a 4 pin modular jack from a phone handset. Once I got inside the Kaypro the jack inside had taken a pretty hard hit and was beyond repair, so I needed the new part. I soldered the replacement in and hot glued it on the inside to improve the support. It feels quite solid.
I was able to drag out another working Kaypro machine and test the keyboard. It was working as expected!
Next, I powered up the Kaypro II machine. The CRT came up, but the normal prompt that appears on power up was not appearing, normally the machine would have a prompt that says
This message appears before booting and so a working floppy drive is not needed to get this message, just a working power supply, main board, and CRT. I checked the power supply voltages and they were OK. On the CRT I did not see any raster pattern when the brightness was turned up, or after adjusting the knobs. I did some basic troubleshooting on the mainboard, and ended up moving the main board over into a different Kaypro. I could see that it was outputting video, so that isolated the issue to the CRT analog circuit. This was discouraging because I'm not the best at CRT repair, but I started doing some reading and found this article on Vintage Computer Forums. I normally don't like doing "Shotgun" repairs, but I replaced as many of the caps as I could from my stock of Capacitors and that helped, now the image looked like this...
There was raster and the CRT was displaying text! Also, I cleaned the disk drives with a floppy cleaning disk, and I made SS/DD Boot Disks for the Kaypro II. The machine booted from the floppy!
The non-centered but visible image was evidence that I needed to complete the recap so I captured the rest of the capacitor sizes and put in an order on DigiKey. When the caps arrived and I had time to get back to repairs on this machine I identified a large capacitor that was totally dead, so once the recap was complete, the image looked great and I completed the CRT adjustments. I now have a fully functional Kaypro II machine...
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I feel quite fortunate to have one of these systems, it's been on my wish list for quite some time. My next project for the Kaypro II 82 will be make some more floppy disks. I'm also thinking about swapping one of the drives for a Go-Tek as it would be really cool to be able to boot and run from Flash Storage.
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