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Here are some (slightly earlier) PCB's for the keyboard, including stabilizers for the futaba (George Risk) keys and for MX keys. The stabilizers are pretty much necessary for the futaba keys and MX...

I have been working on a pet project in my (rare) spare time over the past few months, and figured it's a good time to share it. I would like to create a family of keyboard matrices and interfaces...

I never did, but it's still on my to do list.

The two piece cover on my other SOL also has a hole in that position. Of course, it's covered by the logo.

Nice!

@Sol experts, has anybody seen a SOL-20 with a one-piece cover? I made an offer for a "project" grade Sol on Ebay, and to my surprise it was accepted. When it arrived, I was again surprised to see...

I finally had a chance to try the Cxxxx->Fxxxx remapping. The replacement personality module will accommodate jumpers on the motherboard, but I opted for the less permanent method of soldering a...

Very nice!

Or maybe 00041, or 000H? hard to tell.

I've attached a photo of the inspection stickers. One sticker indicates a date of 4/8/77. It has a number 0004, the significance of which I can't tell. The other sticker indicates another test...

@Corey:

Also, do you happen to recall which paint you used?

Thanks,

Dave

Corey,

I'm interested in reproducing the paper badge as well. Did you print this yourself, or did you have a service print it?

Dave

For anyone interested, I've added the design files to github:

https://github.com/osiweb/Hardware/tree/master/new/sol20/sides

Dave

Ah, yes, I can see the spot weld marks. But since the parts are painted, spot welding them back together is not an option, even if I had a spot-welder. I think the best bet is to epoxy them...

I installed the threaded inserts today. Unfortunately, I installed the upper insert for the right panel in the wrong position, so I have to take it back to the Makerspace (to use the drill press)...

Of course, anybody who randomly probes without thinking gets nowhere. But that person still needs to learn when and how to use the tool.

Definitely, there is no substitute for thinking about the...

The high bit determines the color group, so a stuck bit could produce the symptom, under some circumstances. A faulty bit could be a bad RAM chip, but also a faulty register.

Dave

And to answer more literally, where to connect the probe depends on the board. Sometimes there are convenient test points In many cases, you will probe a ship or discrete device directly holding...

It's a good question. To a beginner, the options seem limitless. A scope only has two or four traces, and they should be meaningful. Hobby time is limited. You must be judicious.

The key, not...

Since it began working after just removing and replacing the chip, you are right that it's probably a socket issue. I was only speculating on the cause of the color issue, since the problem seemed...

That looks like part of the video/DRAM timing generator circuit. Most failures here would result in all-or-none failure modes. The section does output a color burst enable signal. Perhaps the...

If you have access to a large enough ultrasonic cleaner, you can consider dunking the whole keyboard in the bath, or if you have a smaller one, try suspending the keyboard vertically by a wire (or...

You're not generating blue/orange. Looking at the schematic, there's a shift register (A11) that produces a 1 clock-cycle delay to turn green/magenta into cyan/orange.

If A11 failed, most likely...

Actually, I spoke too soon. There is a difference between A85 and the CP/M 8080 assembler. The CP/M assembler maps a string "AB" to memory in order, with 41h at the low byte and 42h at the high...

Almost done. Here are the replacement panels next to the originals (new panels in the center):

56477

I just need to install the threaded inserts.

56476

I tried to use a screwdriver to...