- vcf-midatlantic - lists.vcfed.org

Re: [vcf-midatlantic] Another great repair workshop
by dillera＠gmail.com 06 Oct '19

06 Oct '19

Here are my photos from Sat: https://imgur.com/gallery/T4UfR5j <https://imgur.com/gallery/T4UfR5j> It was a beautiful day to wander around InfoAge and very full repair day. See you in November. -andy

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OT: converting audio tapes to computer files
by Evan Koblentz 06 Oct '19

06 Oct '19

My girlfriend has a couple of dozen audio tapes that she wants converted to sound files. She's willing to pay someone to do it. No editing or optimization needed, only bare files. She nor I are interested in DIY advice. Just looking for someone to do it for her. Not urgent, but it can't take six months either. Reply to me off-list at evan(a)snarc.net.

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Re: [vcf-midatlantic] much ado about chording keyboards
by Eric Rangell 04 Oct '19

04 Oct '19

Hi Jonathan, Let me know if this diagram has what you are looking for: https://github.com/erangell/VCFEast2019/blob/master/KeyboardDecoder.png When a key is pressed, it will connect a Pad to a Rail, so the Q key connects pin 12 to pin 21. The decoder can then send current through each pin and see if any of the other pins are receiving the voltage. Control and Shift can be read independently of other keys using pins 2, 3, and 23. My encoder board is from The Keyboard Company, model # KB20-0016-00. The encoder chip is labelled: 331-0931-B KR3600-070 SMC 8151 with another marking of 8-82. Eric

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Re: [vcf-midatlantic] *OT*, but I don't know how else to contact Ian
by Lou 02 Oct '19

02 Oct '19

Something that I should mention to the community and on here is that I actually live right next to Sewell (Pretty much all of Gloucester is in my reach if it's reasonable, some of Camden/Burlington as well). I can attempt to aquire this TV if need be for Ian, funny thing is he was at my work just this past Monday. The hard part is finding a place to keep it at since I'm pretty sure the fiancee won't be happy about me bringing it home! -Lou

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*OT*, but I don't know how else to contact Ian
by jsalzman＠gmail.com 02 Oct '19

02 Oct '19

Ian Primus... I don't know if you're interested in this, but it seems to be right up your alley, and you're the first person I thought of when I saw this item. https://www.ebay.com/itm/Heathkit-Television-with-Manual-Remote-Vintage-fro… I'd hate to see this get trashed, but I'm not in a position to acquire it myself... even for the $1 asking price. Thanks, Jeff Salzman

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Re: *OT*, but I don't know how else to contact Ian
by Jeffrey Golas 02 Oct '19

02 Oct '19

My uncle had that EXACT TV. Needed constant repair and constantly losing its programmed channels. Cool to see but meh, there are better things to save. Bags

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Sperry/Univac Uniscope 100 Service Manual?
by Jeff G 01 Oct '19

01 Oct '19

Would anyone happen to have a service manual, schematic, or ANY technical info on a Univac Uniscope 100 terminal? I acquired one a few days ago and its dead. I did find that the Computer History Museum has the manual and they are seeing if they can dig it up, but if I can get a full copy or if someone has one locally that would be better. If someone did have one I'd be glad to scan it if possible and make it available. I also found some online posts where the original designer of this posted up original drawings and talked about the thoughts behind the design of it. Some pics of it on my web site as I cleaned it up here: https://www.junknet.net/2019/09/30/sperry-uniscope-100-terminal-acquired/ I also acquired some Sperry/Univac "Mapper" memorabilia at the same time, that I'll be posting up on my web site too. (Known today as BIS from Unisys) Thanks, Bags (aka Jeff G)

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Another great repair workshop
by Herb Johnson 30 Sep '19

30 Sep '19

http://www.retrotechnology.com/restore/vcfrepair_sep19.html I was going to post about my PDP-8/A repairs at the recent workshop; the linked WEb page has details. When I read Evan's post about his LEGO Logo Robo go-go work, I added some photos and links about that, to my Web page. I looked with effort on the Web for "da schematic" for the motor controller, the thing that was "jumpered" in posted discussion. I was surprised to NOT find it. There's info on the Apple II interface card already, as discussed. Odd someone with skills, hasn't drawn this already. There's the usual reasons, mostly like these things are already available for tens of dollars used. Ah - this Web page is informative: http://lukazi.blogspot.com/2014/07/lego-legos-first-programmable-product.ht… Regards, Herb "copper trace" Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT retrotechnology DOT info

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Re: [vcf-midatlantic] A little electronics hack
by Evan Koblentz 30 Sep '19

30 Sep '19

Big squiggly area in the center of the second (bottom) image. On Mon, Sep 30, 2019, 1:48 PM Mark Whittington <markwhi(a)gmail.com> wrote: > > https://4.bp.blogspot.com/-DGOlTkGXj_Q/U8-T2uBG5iI/AAAAAAAAATY/7ra6gVkSKg8/… > > > https://4.bp.blogspot.com/-6RLSsFHgMgY/U8-TzfBRxOI/AAAAAAAAATQ/NeiKlqHPevs/… > > Out of curiosity (and assuming I've found the right board images), do you > happen to know where the circuit that Neville identified as faulty is on > these images? Also, I've found a couple of these units for sale in the US > for ~$85 and in the UK for ~$50 that might be useful for backup or reverse > engineering purposes. > > Cheers, > > -Mark > > On Mon, Sep 30, 2019 at 12:57 PM Evan Koblentz <evan(a)vcfed.org> wrote: > >> >> Looks like someone on this list has already done the legwork on this >> as of 2016... https://www.glitchwrks.com/2016/09/12/lego-logo-interface >> <https://www.glitchwrks.com/2016/09/12/lego-logo-interface> >> >> No - that's the card for connecting the computer to the interface box. >> That schematic already existed and we didn't have the card, so Jonathan >> (Glitch) built one for us. That is what you see documented. In the current >> thread I am referring to the interface box itself. There is more info on my >> personal website at http://www.mindsbeforethestorm.com/8bit_hardware.php. >> >> >> >> On Mon, Sep 30, 2019, 11:16 AM Mark Whittington <markwhi(a)gmail.com> >> wrote: >> >>> Looks like someone on this list has already done the legwork on this as >>> of 2016... >>> >>> https://www.glitchwrks.com/2016/09/12/lego-logo-interface >>> >>> On Mon, Sep 30, 2019 at 9:13 AM Evan Koblentz via vcf-midatlantic < >>> vcf-midatlantic(a)lists.vcfed.org> wrote: >>> >>>> >> If you're interested in investigating further if you point us to >>>> schematics we can give suggestions. >>>> >>>> I am giving the box to Neville in early November (don't want to risk it >>>> not >>>> working before the Brickfair NJ event the first weekend of that month). >>>> He >>>> agreed to my request to make a schematic of it. >>>> >>>> The next step will be to have someone else take his schematic, build >>>> one, >>>> and send it back to me for testing. That'll prove that the box can in >>>> fact >>>> be built from just the plans. After that I'll post it on my website. >>>> >>>> A possible third stage would be to make modern improvements, if any >>>> ideas >>>> stand out. >>>> >>>> I'm only interested in the function, not in replicating the physical >>>> case. >>>> But what I would avoid is replacing the vintage computer with a >>>> microcontroller. I'm all for a better interface but strictly against >>>> some >>>> non-vintage computer experience. >>>> >>>> >>>> >>>> >>>> On Mon, Sep 30, 2019, 8:43 AM David Gesswein via vcf-midatlantic < >>>> vcf-midatlantic(a)lists.vcfed.org> wrote: >>>> >>>> > > >> It's called a 'crowbar' circuit. Prevents things from burning >>>> up. >>>> > > >>>> > >>>> > What I normally called a crowbar circuit is the overvoltage protection >>>> > where it intentionally shorts the output of the power supply. This >>>> sounds >>>> > more like over current protection. >>>> > >>>> > > What are common reasons why those stop working? Neville and I >>>> didn't see >>>> > > any obvious signs of damage to it. >>>> > > >>>> > Either component value shift or failed component. You indicated that >>>> it is >>>> > driving the motors better than it ever has. It may also be your motors >>>> > are a heavier load than it was intended to drive. >>>> > >>>> > If you're interested in investigating further if you point us to >>>> schematics >>>> > we can give suggestions. >>>> > >>>> > >>>> > > On Sun, Sep 29, 2019, 1:56 PM Mike Loewen < >>>> mloewen(a)cpumagic.scol.pa.us> >>>> > > wrote: >>>> > > >>>> > > > On Sun, 29 Sep 2019, Evan Koblentz via vcf-midatlantic wrote: >>>> > > > >>>> > > > > Neville noticed something that I wouldn't have. The circuitry >>>> > contains a >>>> > > > > safety mechanism to shut off all power if the current jumps too >>>> high, >>>> > > > such >>>> > > > > as a kid inserting a paper clip. There's probably a technical >>>> name >>>> > for >>>> > > > that >>>> > > > > but I do not know it. Anyway, for unknown reasons this circuit >>>> was >>>> > > > kicking >>>> > > > > in! He jumped it with an equal-length wire. :) >>>> > > > >>>> > > > It's called a 'crowbar' circuit. Prevents things from >>>> burning up. >>>> > > > >>>> > > > >>>> > > > Mike Loewen >>>> mloewen(a)cpumagic.scol.pa.us >>>> > > > Old Technology >>>> > http://q7.neurotica.com/Oldtech/ >>>> > > > >>>> > >>>> >>>

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A little electronics hack
by Evan Koblentz 30 Sep '19

30 Sep '19

Yesterday at the workshop I took out the Laser 128 and circa-1987 Lego electronic parts. They'd been packed away since Maker Faire last year. My new robot barely worked, despite being almost identical to the old robot and running the same software. I found a loose wire connector which Ian fixed. Still had a lot of problems. Neville (a retired EE who first joined the old MARCH group in the mid-2000s and recently came back) started testing things with a meter and scope. He figured out that some of the interface box outputs were only producing half their usual power. We opened the box (a couple of years ago I swapped its plastic rivets for screws). Nothing seemed wrong. It was clean and all of the capacitors looked good for 30+ years old. Neville noticed something that I wouldn't have. The circuitry contains a safety mechanism to shut off all power if the current jumps too high, such as a kid inserting a paper clip. There's probably a technical name for that but I do not know it. Anyway, for unknown reasons this circuit was kicking in! He jumped it with an equal-length wire. :) We tried the robot again. What a difference! Even before it stopped working last year, the motors always seemed kind of weak. I just assumed that was normal because I never knew it any other way. Now I see what normal is supposed to be. The motors run MUCH stronger! It's an amazing improvement. Neville also resoldered a loose LED connector and one suspect cold joint. So I'm a happy camper. The electronics for this set are running better than ever, which means I can focus on the Lego side and the software. I'm giving a big presentation about all of this Lego stuff on Friday, Nov. 1 at Brickfair NJ and then exhibiting it there Saturday and Sunday. Now I do not have to worry so much about the demo aspect failing.

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