One of the machines near the top of my acquire list is a Sol-20. The last one I saw for sale went for about $1000... is that pretty typical? Are they comparable in rarity to the Lisa, etc? Havent seen one up in a while now.
Also is there anything to be on the lookout for with these? Things to be desired or avoided?
These days, if you got one for $1000, it wouldn't be running and would be a rust bucket.... The Sol-20 is a great system, but they are not the easiest to get and keep running because they are an "integrated" system not like most S100 systems where you could "simplify" the system to figure out what is going on.
If you check eBay history, there hasn't been a working one sold in a couple of years... The cosmetically decent ones have been going for around 2k, with out proof of running...
There are exceptions, my second Sol-20, I grabbed on a buy it now for $500 (It was up for less than couple of minutes when I saw it and grabbed it), cosmetically it was perfect because I don't think it ever worked. It must have been built and shoved in a box when the person couldn't get it working. It took me a long time and required some investment in equipment I didn't own like a logic analyzer and an 8080 ICE to sort it out which turned out to be a defect, there was short under the PCB I had to fix with a razor blade. There are more than a few Sol-20 that never ran back in the day that were purchased as kits, maybe they had similar quality issues. This system also had a factory modification having to do with the transformer having a brown out setting that could cause a problem in the system if you didn't have enough S100 cards plugged in to draw enough current. The factory modification had a minor problem I had to fix.
My first Sol-20 didn't have much electronically wrong with it other than a bad 74H00 and some bad 2102 ram chips, which all was easy to track down with the schematics and an oscilloscope. I also had a bad big capacitor in the PowerSupply which stumped a couple of people who tried helping me out, but in the end it was a simple fix. Cosmetically it was a basket-case. It was completely rusted, and scratched up. I completely tore it down and disassembled it down to every screw. I had to repaint the green on the fan, touchup and clean up the case, wire brush with an air tool the entire chassis, replace the plexiglass, replace the logo strip with a new one and replace some of the card guides. I also sanded down the sides and re-finished them and repaired a couple of other minor cosmetics things as I recall. Oh and it was missing the fuse holder back which turns out to be a very difficult to find a replacement, but I did.
Both needed Keyboard rebuilds, and a calibration of the PLL for the cassette interface. I also performed all the ECN changes for my boards which were Rev D. Finally I replaced every single tantalum cap on the board and in the power supply.
I also revived a Sol-20 at the MARCH museum at the InfoAge Science center. For that one I used an IC tester one afternoon on every chip and simply swapped out any bad chips. It was a factory built unit so it was much easier to be confident if something went wrong it was a chip or something like that. I also had to rebuild the keyboard, calibrate the PLL and replace one of the big caps in the power supply.
Cheers,
Corey
