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New Sol-20 Owner

snuci

snuci

Veteran Member
Joined
Nov 22, 2012
Messages
1,551
Location
Richmond Hill, Ontario, Canada
I am the proud owner of a Sol-20! This is my semi-first S-100 computer. My first is a KIM-1 with a KIMSI board that would accept S-100 cards but I didn't really want to mess with that.

Anyway, I was a little disappointed that the cpu was a purple ceramic AMD AM9080ADC. Did these ever come with white C8080s? I'm missing the rear fasteners that apparently are not screws. If anyone can tell me what I can use to replace these, please let me know. It looks to be in great shape. It has the Solus-1 personality module but no other S-100 cards. It came also came complete with a Sanyo VM4092U monitor that fits perfectly with the era.

I don't know if it works because it was dropped off outside and it has some condensation on it from the cold so it waits until tomorrow to see if it works. When asked via email, the owner didn't really answer if it worked or not so I don't hold much hope that it will but you never know... Even if it doesn't work, out of the gate I'm still very impressed and will be asking for help. I have no manuals but have found them online.

This doesn't look like it was built as a kit if soldering was involved. Did the kit come with a bare board and you had to solder components or was it full of sockets that you simply placed the chips into?

Thanks for any help. I am very happy to have this little piece of history.
 
Congratulations! First to answer your question, the SOL-20 was in pieces and they even had instructions on how to treat the wood side panels to make the computer more visually pleasing so that your wife would not kick the computer to the garage. Seriously. :)

But my Dad has a Sol Terminal 20 complete with floppy drives. I've been working with my Dad over the last few years to understand how to maintain the Sol. Great computer. A few weeks back I used the Sol to call a BBS (which handled 19.2K pretty well), to telnet out to a IRC chat room. All and all it went well, even though the built in terminal did not have VT100 emulation. But I was still able to make out what was going on.
 
Congrats...

First... Most of the Sol-20 had the purple TI or AMD(Early) or a plastic 8080 (late). PT used what ever they could get cheaply. I have a very early Sol-20 with a white 8080 and one built a couple of months later with a purple.

As for the screws, they are impossible to find (I've tried) and to be honest I have a set and never put them on (I just keep them for completeness). No reason, with the built in riser card and the crowbar in the power supply, its the perfect test machine for cards.

As for being a kit, PT produced both a kit and factory built. Both will have rework on the bottom in most cases as there were PCB mistakes that had to be corrected to get a system working right using a razor blade and jumper wires.

My first suggestion before powering on is to use a variac on the supply while it's unplugged from the motherboard. Those are big caps and you don't want a problem. Then I'd check the supply out before plugging in. Then I'd plug load into the supply using a power resistor and check the voltages. When it finally passed, then I'd plug it into the MB and start working. The onboard ram on the machine is only for Solos and Video, so you will need an S100 card to do anything useful. I also think you will need to rebuild the keyboard by replacing the foam. So it you get a prompt and the keyboard doesn't work, no worries it's normal for an old machine with a capacitive discharge keyboard to have an issue.

Otherwise, good luck and if you have any questions, just post them... we will all try to help.

Cheers,
Corey
 
Well, got it all hooked up and ready to go and the fuse blows when connected to the motherboard. When not connected to the motherboard, the power supply and fan run until I turn it of. I'll have to check it. The original fuse was still in it and good so a short must have developed over time?

I'll have to trace it out once I locate a schematic. Is there anything common that this might be? I imagine there's nothing common about these :)
 
I don't know anything about the Sol-20 (yet), but if the power supply filter capacitors are on the motherboard, $10 says there's your problem.
 
Thank you for trying. Turns out it's a wonky power switch that doesn't work too well. I've also disconnected the vertical bus extender for now.

I now get a screen of 9 lines of "90909090". That's progress. Still deep in the manual. What an awesome resource!
 
The power switches do stick, you can clean it with dexoit and it will be fine.

as for the 90909090, check the following...

First check for bad 2102 on board ram in u3-10. It's not the video ram, that would cause weird characters.
Check the following chips U22,23,24,36,47,48,61,65,66,76,77,78,79,83

Cheers,
Corey
 
I tried to reseat the memory but other than that, I don't have memory to try to replace. I went from 9 lines of 9090 to 16 lines, to 1 line to 9 lines and am back there.

I tried to clean up the switch but it still blows the occasional fuse with a pretty decent flash. I'll need to get a new switch before I run out of fuses at my local store :) I'll did find a similar switch on eBay. It's an Oslo Controls switch. Is the original supposed to light up? Mine had a red solid cover over it a white switch that looks like it might light up. I was thinking that may the light bulb was bad and that's why it sparks occasionally. The one I ordered illuminates, I think.

This will be an interesting project. Thanks for the help Cory.
 
I ordered some 2012's. I figured that since I'm getting into uber-vintage, they might come in handy whether I need them or not. I got 18 just to be sure. I also ordered the switch. What a great looking computer.

I already have the keyboard pads too. I made an extra 100 for backups when I made them for my Apple Lisa's. It didn't occur to me at the time that they would disintegrate with the others in time until I thought about it later. Once you start pounding them out with a punch, though, it's hard to stop :)
 
I purchased a Sol-20 off eBay a few weeks ago. I'll be joining you in the restoration process!

Right off the bat, I have to replace the power switch, the C14 power entry module and at least one 2102 (physical damage apparent). The power supply actually looks good under load tests. I found and ordered a power switch. I have multiple brands of C14 modules, but none of them fit the cutout in the Sol-20 -- they're all a bit too big. I did find a European brand C14 module on Mouser that looks like it will fit.

Mike
 
Hello Mike,
please measure the cutout in metric. I look then if i have it.
Frank
 
Hi Mike,

Congrats!
How do you know you need a C14 power entry module? To be sure, we are talking about the socket for the power plug, right? Mine is pretty loose but it works. When I turn on the Sol-20, most times I get a spark that blows the fuse but I'm pretty sure it's just the switch.

Just yesterday I got a SD Sales 64K EXPANDORAM DRAM board and I'm wondering if I can remove the stock memory and use it alone. Does anyone know if it's that easy? I do have to adjust the board for the 8080 because it's configured for a Z80 but that won't take long. I thought I saw a note about this board and the Sol-20 so I'm going to do some research before I play with it. My 2102 memory is on it's way so I may just wait the week or so.

Good luck!
 
Yes, the C14 is the socket for the power plug. Power cuts in and out with slight bumps of the power cable (or table). I tried a couple of different power cables in hopes of finding one that grabbed the C14 prongs a bit tighter, but several power cords all exhibit the same problem.

I have that same SD Sales 64K Expandoram running in an Altair 8800 and it works fine. As you mention, it does requires configuration based on the system and CPU type, but it work reliably even without a Z80 to initiate DRAM refresh. The only downside with the board when running in an Altair is that when data from RAM is zero, the front panel data LEDs glow slightly due to the refresh cycles. This is not an issue with the Sol of course!

I'm not yet a Sol-20 expert, but I don't believe the 64K RAM card will let you work around the bad on-board RAM since, from what I can tell staring at the schematics, memory space access in the C000-CFFF range will always go mainboard RAM.

Mike
 
Corey986 said:
As for the screws, they are impossible to find (I've tried) and to be honest I have a set and never put them on (I just keep them for completeness). No reason, with the built in riser card and the crowbar in the power supply, its the perfect test machine for cards.
Click to expand...

Corey, would you mind taking a picture of the screws next to a ruler? I also want them for completeness and the quest for stuff like this is part of the fun.

I would really appreciate this (while I wait for my memory and power switch).
 
Has anyone noticed that there have been a lot of Sol-20's on ebay recently. I think I've seen only about 2 in the last 2 years, but about 5 in the last 2 months!!!!

What's up with that!!!

P
 
You're right. I personally picked mine up on Kijiji but the owner was on vacation for a few weeks so I watched them for a while during the wait. I think I only saw one during the previous six months that sold when I looked at prices to determine if what I paid was worth it. It was regardless of cost :)
 
smp said:
Hi Mike,

So, are we expecting to hear of a new Sol-20 Clone project coming soon?

;-)

smp
Click to expand...

Too much work! The Altair Clone ended up being way more work in the end then I ever imagined. All good work though -- I really enjoyed it and learned a lot!

Mike
 
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