This Kaypro II computer has led a hard life, but it’s on the road to recovery now. A previous owner has modified it quite a bit, but some of the modifications are hack-jobs. I’ll probably need some help identifying some of the upgrades to determine whether I want to keep them or back them out, but there are a few changes that are definitely coming out.
The worst offense was the relocation of a contrast control (it’s labeled “BRIGHTNESS”, but it’s technically a contrast adjustment) from the back panel to the front. The control is simply a potentiometer inline with the video signal wires from the main board to the monitor board. It acts as a resistive voltage divider in the luminance signal, while the sync signals are left alone. The normal connection between these boards is just a few unshielded wires; video bandwidths were low in those days, and shielding was a bit of an afterthought.
The original connection was pretty short, and the wires weren’t nearly long enough to reach to the new location on the front panel. So, the previous owner extended the wires… with speaker cord. And spliced the speaker cord to the original wires with wire nuts. Yes, you read that correctly: WIRE NUTS. Big orange ones.
The front panel has a few holes for me to patch up. One for the contrast control, one for the reset button (also relocated from the rear panel), and one for a toggle switch connected to an upgrade board that’s plugged into the CPU socket. There are also signs of some previous modification inside that has been removed: a new cable was spliced into the power harness, and an RCA jack was mounted on the rear panel, both with their connections left dangling inside the case. I have no way of knowing what they might have been connected to, but there are some foam tape remnants on top of the floppy drive subchassis that might have held some sort of board in place.
It’ll take a while for me to reverse-engineer the various modifications to determine what should stay, what should stay be be re-implemented, and what should go. The system probably needs repairs too, and I’m not quite ready to try applying power to it yet. But I’ve already undone that terrible contrast control hack, just so I can sleep at night.