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Sol-20 with Helios II drive

snuci

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I thought I'd post a new find here that I'm excited to have found.

I was able to acquire a Sol-20 with a Helios II disk drive. Both are in almost pristine shape but I am missing any internal S-100 cards so the Helios II is a door stop for now until I can find the Helios II controller and formatter cards :) The true find is the Helios II unit that looks to be in great shape but as Corey986 has suggested to me off-line, it will need some preventative restoration (new caps) and some testing to see if it works. Sadly, I can't try the latter without the cards but i have some great reference material to look over in the meantime.

I will, however, be looking over the Persci 270 drive very carefully and replacing the caps at the very least. I don't tend to do this but it has been suggested by a couple of sources and the rarity of the slightest chance this is a working example makes me a little more cautious than normal. I also have a large metal cap in the power supply that needs to be replaced as per a Processor Technology bulletin but I have no idea where I'm going to get that new cap :)

Here's a few pics of the Sol-20 and Helios II:
Sol-20.jpgHelios II - 2.jpgHelios II -1.jpg

More pics of the Helios II at http://vintagecomputer.ca/?computers=processor-technology-helios-ii
 

JDallas

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Please document your cap replacements by posting them online. You might help someone out with the task years later.

That's a beautiful system you have there. I always thought the SOL-20 was the best looking computer of its day... Digital Group out of Colorado had some nice looking equipment too but I've heard next to nothing about them in a Vintage Computer context. I just see them when looking through my old BYTE magazines. :S
 

Corey986

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The two bolts on the front seem very strange. I have never seen a helios with that setup. Does it look like it's original or did someone drill and countersink the holes to secure the drive and then touched up the black paint? What I have seen are some helios secure the drive from underneath only and some like mine from underneath and an extra bolt on top from the front panel.

Cheers,
Corey
 

snuci

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The two bolts on the front seem very strange. I have never seen a helios with that setup. Does it look like it's original or did someone drill and countersink the holes to secure the drive and then touched up the black paint? What I have seen are some helios secure the drive from underneath only and some like mine from underneath and an extra bolt on top from the front panel.

Cheers,
Corey

There really aren't many picture of Helios IIs out there so I don't really know what's normal. It certainly looked normal to me but I can inspect that a little better. I have seen one picture with no front bolts but the one on this page looks like it has them as well (if you look carefully) http://oldcomputers.net/sol-20.html
 

snuci

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Please document your cap replacements by posting them online. You might help someone out with the task years later.

I like doing that because I find old posts very useful so I'll be posting updates here so this is where those updates will be. I'll be using the "Cromemco/Persci 277 Alignment and Repair" guide by Martin Eberhard publicly posted here: https://docs.google.com/file/d/0B-XdfCubTNJJeW5UdjVyWGdxUXM/edit?usp=sharing Corey sent me a newer copy but I'm not sure it is posted anywhere. This is for a Cromemco drive but the internal drive mechanism is the same and some of the information is valid for the Persci 270. I will be supplementing it with information in the "EPT Vol 9 - Helios Service" guide poosted here: http://www.hartetechnologies.com/manuals/Processor Technology/EPT Vol 9 - Helios Service.pdf.

If anyone has gone through a restoration of a Persci 270 or 277, I'd love to hear more. I am working with Corey on this because he's restored a drive. We will continue the conversation here as it progresses.
 

snuci

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Well, I checked my Sol-20 and plugged it in to see if I had the right BOOTLOAD personality module to match the Helios II. I did get the ">" prompt but I couldn't hit "enter" because my keyboard pads need replacing. I went to the dollar store where I bought my previous weather stripping to make new pads and they were out. I'm not sure if they'll stock that item again as dollar stores are so now I'm hunting for 1/4" two-sided sticky foam weather stripping.

I have another Sol-20 so maybe I'll swap keyboards temporarily to check the personality module. Corey has mentioned that the test is to see if there is a "boot" command in place of the "term" command. This personality module looks like this:
Sol-20 Personality module.jpg

I also spoke to the original owner and the internal S-100 cards are gone so I am in need of the Helios II controller and formatter cards. Can't do much without them. I did shelve the Helios II for now (literally) and my back wasn't too happy about that. Why was the bottom made of cast iron? No wonder it weight 60+ pounds!
 

Corey986

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Home Depot sells low density foam that is perfect for a keyboard rebuild. Make sure you get the low density stuff it feels just like the original stuff. Took me a few minutes to find it as it tends to be on a lower shelf in the two Home Depot stores I have bought it in (I also did a Lisa keyboard for the MARCH museum recently).

Cheers,
Corey
 

mloewen

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Home Depot sells low density foam that is perfect for a keyboard rebuild. Make sure you get the low density stuff it feels just like the original stuff. Took me a few minutes to find it as it tends to be on a lower shelf in the two Home Depot stores I have bought it in (I also did a Lisa keyboard for the MARCH museum recently).

Corey, what is the product name for the foam you used? I used model RR track bed foam for a Model II rebuild, which is a little stiffer than the original keyboard.
 

snuci

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I'll check if I have the packaging, if not next Home Depot trip I'll take a pic of the package.

I think it might be this one: http://www.homedepot.com/p/MD-Build...ensity-Foam-Weatherstrip-Tape-02071/100665371

The disks are 7/16" (that's the size of my punch) and 1/4" deep so this should work.

Unfortunately, it doesn't look like we have this in Home Depot Canada stores. I've looked before so I was interested in the packages too.

I have heard of deramp5113's suggestion before but didn't have the link. Thanks for that. I actually do like making them though so I'll try a couple of local hardware stores and see if I can find the low-density weather stripping before being forced to purchase the keyboards. They are a good price.

Thanks guys.
 

Corey986

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Just want to mention I couldn't find the package, but tomorrow is Saturday and that always means a trip to home depot for something on the "honey-do" list so I'll take a pic and post it tomorrow.

Cheers,
Corey
 

snuci

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A quick update from me too. I think I found some open cell foam weatherstripping that will do the job at Home Hardware in Canada. As it's commercial grade, the stores don't stock it but I've ordered it for pick-up and will check to see if it's sufficient next week when it arrives. This is open-cell foam so it should be suitable.

Here's a link for anyone in Canada that may be interested: http://www.homehardware.ca/en/rec/i...5-1-2-Foam-Weatherstripping-Tape/_/R-I2395278
 

snuci

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Still waiting for the weather stripping but did swap keyboards on my working Sol-20 and it turns out that the personality module in the Sol-20 that came with the Helios II does not have the "BOOT" command but has the "TERM" command. I tried >BOOT and >B. When I type TERM, the cursor goes away so I'm assuming it's in terminal mode and expecting data from the serial port. The output is in the pic below.

I'll need to get a BOOTLOAD personality module (or 4 programmed MM5204 chips) for it now but I don't understand how the Helios II worked with it. I acquired it from the original owner and they went together. Could it be that the original owner typed in the boot stub each time?

All this said, this Sol-20 is earlier than my other two Sol-20s. The keyboard was Rev B. I also have a Rev C and Rev D. The 8080 is also white ceramic as opposed to the purple ceramic. It also doesn't have a spec of rust or corrosion under the keyboard.

Anyway, here's what the output looked like.
SOl-20 Boot.jpg
 

Corey986

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Yep not a helios boot personality module.

So now you have to make sure all the "fixes" are done to the motherboard to make it do DMA correctly for the helios and to make sure that the swapped lines on the s100 bus are fixed.

Cheers,
Corey
 

snuci

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Hrmm... I thought I posted a reply this morning but I guess I didn't submit. Or I do what I usually do and hit the "Reply to Thread" above this box and to the left by accident.

Corey, is this documented in the EPT manual as a revision (or two)? Any pointers are much appreciated.

As an update, I found the vlaues of all the caps that Martin's guide suggests that should be replaced and they're all 1uf. That makes things easy :) I need to get them ordered and then start the dismantle and checks when those come.

Thanks.
 

Corey986

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Not really any pointers to doing the mods, just make sure they are done.

As for the foam, I bought another package so I had some spare stock at home. It's frost king, L344.
 

snuci

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Quick update: I made my keyboard key pads this past weekend. The weatherstripping I bought was 35 feet long so I got a few pads out of it :) I had to buy some two sided tape because the weatherstripping was only sticky on one side. I bought the tape from Michael's (arts and crafts store).

keyboard foam pads.jpg

I also replaced some caps as suggested in Martin's guide linked in this thread and fired her up. I don't really know what it's supposed to sound like but it seems to be okay. Corey, did you have a video (with audio) on yours? If not, I'd love to see one.

I am now waiting for the Helios II cards (from Martin himself so I know they work) and am waiting to try it out. Should be any day now.
 
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