View Full Version : Kaypro 10 video problem

March 1st, 2013, 03:50 PM
12138I took a chance on a Kaypro 10 on Ebay, I was looking for the later model with the clock and modem and thankfully that is what I got! There is a problem with the video display. I get a series of vertical lines and you can see the boot up sequence dimly in the background. It won't do a disk directory but it does seem to boot. I've tried the more obvious things like trying a different power supply and looking for obvious NFG caps. I have reseated some of the chips. It does have a turbo BIOS - at least that's what it says. I have an older 10 motherboard and a couple 4/84 motherboards that i can get parts from.

March 1st, 2013, 08:15 PM
Well, if I had to guess, my first culprit would be U10, the 81-189 custom gate array.

March 2nd, 2013, 06:58 AM
I tired U-10 first but no joy.
I DID FIX IT though, it was U-9, the character prom.
The screen is a little out of alignment at the bottom. I hope it's just an adjustment.

March 2nd, 2013, 02:26 PM
Well as usual I may have spoken too soon. Replacing the character prom U9 81-235 cleared up the display but now the bottom of the display is not correct.
I get 15 rows and then rather than scroll it comes up a line overlaying the other lines until it gets to 24. Needless to say something is wrong. When i do a CLS everything is fine up to 15 rows. I tried another 81-235 prom and no difference. Could it be the BIOS? It's an advent turbo bios v3.4 (28-pin) on I am assuming is a 2764 EPROM. Is this BIOS available online? I tried a 302 bios (24 pin) from an older K-10 but no joy.

March 7th, 2013, 03:58 AM
I've had video and power supply problems with my Kaypros that can be traced back to leaky electrolytics. I've recapped the video and power supply boards on two of my Kaypros (even found a resistor or two that needed replacing).