Erik_
Yeah, it probably is. I don't really trust my ohm setting
Sun Sep 11, 2022 12:25am

on my meter. It's sort of an "on/off" type of thing. (Need to replace it).

Final solder job with some reflowed and flux cleaned off. There's two pins on the left side that look like they could use a tiny bit more solder but I think it might be okay.


Cartridge slot switch bypass jumper soldered in. (Little bridge on the top two pins.


So, all was going good. I had the thing working for a while apart and had no issues. I then started putting things back together. I put the big shielding on and stuff.. still no issues. I put the case together (against my own gut feeling). I had some issues with the screen flickering on channel 3. I swapped it over to channel 2 and it was fine. The channel change switch is also on the fritz but as long as it works on one channel, I'm okay with it for now.

So, things are all together and I'm testing BASIC out. Absolutely no issues. Everything works great. My bypass jumper is working as well. Then, I try the floppy drive. That loads up the print program without any issues. The belt is a little tired so it keeps me from really clamping the drive down the full way. I had tried to clamp it after it loaded the program but then it didn't spin going to one of the options. I opened the drive a bit and it spun but kicked me back to BASIC.

Trying to load back to the disk from BASIC didn't work. It started to load but then went back. So, I did a reboot. Rebooted right back into the disk program without any issues buuuuuuuuuuuuuuuuuuuuuuuutttt THE KEYBOARD STOPPED WORKING AGAIN!!!

I rebooted the computer a few times and it still wasn't working. I can't image something got jostled free, there was literally no movement on the computer except the power switch between it working and not.

So, here I am again with the keyboard not responding. I have a sinking feeling that if I pop the connector for it out and back it will work again. When I put the case on, I had to route the ribbon a different way than when I had it apart and running. When its in the case, the keyboard ribbon wraps around the power supply board so I guess it's possible the little bump from flipping the switch did it.

Or there's some other small component somewhere on there that's failing intermittently.

The saga continues...


  • 60 kOhm seems too high. - Puckdropper, Thu Sep 08 2022 6:03am
    Usually pullup resistors are 5-10k, but I'd think your keyboard should read either infinite ohms or 0 ohms with respect to ground.
    • Yeah, it probably is. I don't really trust my ohm setting- Erik_, Sun Sep 11 2022 12:25am
      • Is it just my angle or is there a bridge on the right-hand s - Puckdropper, Mon Sep 12 2022 11:36pm
        side above the jumper resistor? A trick with dirty switches is to move them back and forth a bunch of times, like 100 or more, until the contacts clean themselves off. If it's one of the more open types, you may be able to squirt some CRC 2-26 (from Home Depot) in there to help clean the contacts.... more
        • I think it might be a piece of paper towel - Erik_, Tue Sep 13 2022 1:53pm
          from me wiping the rubbing alcohol off. Yeah, I've flipped it a bunch and cleaned it with CRC QD Electronic Cleaner. It's much better than it was. Probably just needs some more "back and forth". I think it is that keyboard connector. I just took a few minutes and removed the 4 screws that hold... more
          • Is it just a ribbon cable? - Puckdropper, Thu Sep 15 2022 4:30am
            I never got the tools to properly work with one, but they're pretty straight forward. You can probably put a new end on by smashing it into a new connector, but who knows how good of termination you'd get. If it's like an IDE cable, it's just headers and sockets.
            • Sort of... - Erik_, Sat Sep 17 2022 12:44am
              Here's a pic I found online It's more like through hole IC pins on a "ribbon" like cable. I could solder another connector that plugs into the board onto these pins but might be easier to replace the socket on the board first.
              • I see. It does sound easier to work on the board first - Puckdropper, Thu Sep 22 2022 5:10am
                Hopefully that's where the problem is. I think I saw something like that on a "make it a 286" chip upgrade. You pulled the 8088 out of the motherboard and plugged it into the board. You could then switch via a toggle switch between your 8088 and 80286. Of course the cable is missing on mine!
"Forces act when not restrained" - Puckdropper