August 2018 - vcf-midatlantic

Re: [vcf-midatlantic] Schematic work needed
by Bill Degnan 29 Aug '18

29 Aug '18

this is for a presentation slide, not to build the thing On Wed, Aug 29, 2018 at 11:05 AM RETRO Innovations via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > On 8/29/2018 9:49 AM, Kyle Owen via vcf-midatlantic wrote: > > Why would ohming out this board not yield a 100% correct schematic? I see > > no tricky components that would confuse an ohmmeter except the address > > switch, which could be unsoldered. > > Many of the signals go under the ICs. Sometimes, you can hold to a > light and see through the PCB and validate where they go, but other > times, I have missed wires connecting to more than 1 pin of the IC under > the IC. Ohming, if applied verbosely for each signal around the IC > compared to each IC pin, should find all of them, but I don't think I > would promise 100% perfection without spinning a PCB and testing the > completed unit. > > Maybe everyone else is better at ohming out boards and the hidden > signals under ICs never bother anyone else, but I've gotten hit twice by > them on two different efforts. > > Jim >

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Re: [vcf-midatlantic] Schematic work needed
by alan＠alanlee.org 29 Aug '18

29 Aug '18

Sure. If Evan can wait till next week and Eagle or Altium is fine. Sent from my Verizon LG Smartphone ------ Original message------From: systems_glitch via vcf-midatlanticDate: Wed, Aug 29, 2018 11:48 AMTo: vcf-midatlantic;Cc: systems_glitch;Subject:Re: [vcf-midatlantic] Schematic work needed Sounds like we've got plenty of volunteers, then! :P Thanks, Jonathan On Wed, Aug 29, 2018 at 11:45 AM alan--- via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > It's two 8 bit opposing latches and some address decoding glue. If one > knew the port address, you could create the schematic blind and be 98% > correct. > Sent from my Verizon LG Smartphone > ------ Original message------From: Kyle Owen via vcf-midatlanticDate: Wed, > Aug 29, 2018 11:17 AMTo: vcf-midatlantic;Cc: Kyle Owen;Subject:Re: > [vcf-midatlantic] Schematic work needed > On Wed, Aug 29, 2018 at 10:05 AM RETRO Innovations via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > > > Many of the signals go under the ICs. Sometimes, you can hold to a > > light and see through the PCB and validate where they go, but other > > times, I have missed wires connecting to more than 1 pin of the IC under > > the IC. Ohming, if applied verbosely for each signal around the IC > > compared to each IC pin, should find all of them, but I don't think I > > would promise 100% perfection without spinning a PCB and testing the > > completed unit. > > > > Maybe everyone else is better at ohming out boards and the hidden > > signals under ICs never bother anyone else, but I've gotten hit twice by > > them on two different efforts. > > > > Yes. If you do not completely ohm out each pin/component, I could very much > imagine generating an incomplete schematic. The netlist generated by ohming > out the board should have every pin on every component by the time you're > done. If not, you've missed something. With some conditional formatting, > it's possible to highlight possible errors like duplicate entries, too many > pins per component, etc. > > Hidden traces are no problem *if* you are not relying on visuals, but > rather the ohmmeter. > > And if you're using a Fluke, don't forget to hold down the yellow button > when turning it on, lest you have it automatically power off while you > attempt to ohm out the board. Ask me how I know... :) > > Kyle >

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Re: [vcf-midatlantic] Schematic work needed
by alan＠alanlee.org 29 Aug '18

29 Aug '18

It's two 8 bit opposing latches and some address decoding glue. If one knew the port address, you could create the schematic blind and be 98% correct. Sent from my Verizon LG Smartphone ------ Original message------From: Kyle Owen via vcf-midatlanticDate: Wed, Aug 29, 2018 11:17 AMTo: vcf-midatlantic;Cc: Kyle Owen;Subject:Re: [vcf-midatlantic] Schematic work needed On Wed, Aug 29, 2018 at 10:05 AM RETRO Innovations via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > > Many of the signals go under the ICs. Sometimes, you can hold to a > light and see through the PCB and validate where they go, but other > times, I have missed wires connecting to more than 1 pin of the IC under > the IC. Ohming, if applied verbosely for each signal around the IC > compared to each IC pin, should find all of them, but I don't think I > would promise 100% perfection without spinning a PCB and testing the > completed unit. > > Maybe everyone else is better at ohming out boards and the hidden > signals under ICs never bother anyone else, but I've gotten hit twice by > them on two different efforts. > Yes. If you do not completely ohm out each pin/component, I could very much imagine generating an incomplete schematic. The netlist generated by ohming out the board should have every pin on every component by the time you're done. If not, you've missed something. With some conditional formatting, it's possible to highlight possible errors like duplicate entries, too many pins per component, etc. Hidden traces are no problem *if* you are not relying on visuals, but rather the ohmmeter. And if you're using a Fluke, don't forget to hold down the yellow button when turning it on, lest you have it automatically power off while you attempt to ohm out the board. Ask me how I know... :) Kyle

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Re: [vcf-midatlantic] Schematic work needed
by Kyle Owen 29 Aug '18

29 Aug '18

On Wed, Aug 29, 2018 at 10:05 AM RETRO Innovations via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > > Many of the signals go under the ICs. Sometimes, you can hold to a > light and see through the PCB and validate where they go, but other > times, I have missed wires connecting to more than 1 pin of the IC under > the IC. Ohming, if applied verbosely for each signal around the IC > compared to each IC pin, should find all of them, but I don't think I > would promise 100% perfection without spinning a PCB and testing the > completed unit. > > Maybe everyone else is better at ohming out boards and the hidden > signals under ICs never bother anyone else, but I've gotten hit twice by > them on two different efforts. > Yes. If you do not completely ohm out each pin/component, I could very much imagine generating an incomplete schematic. The netlist generated by ohming out the board should have every pin on every component by the time you're done. If not, you've missed something. With some conditional formatting, it's possible to highlight possible errors like duplicate entries, too many pins per component, etc. Hidden traces are no problem *if* you are not relying on visuals, but rather the ohmmeter. And if you're using a Fluke, don't forget to hold down the yellow button when turning it on, lest you have it automatically power off while you attempt to ohm out the board. Ask me how I know... :) Kyle

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Re: [vcf-midatlantic] Schematic work needed
by Kyle Owen 29 Aug '18

29 Aug '18

On Wed, Aug 29, 2018 at 9:33 AM RETRO Innovations via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > > I stand by my original position. While I agree with Kyle that card in > hand DMM efforts would likely lead to a good approximation in a short > time period, ensuring a 100% correct conversion really requires building > a unit and testing. > Why would ohming out this board not yield a 100% correct schematic? I see no tricky components that would confuse an ohmmeter except the address switch, which could be unsoldered. First thing I typically do is label each component if not already labeled. I'd probably prefer U1 versus IC1, and I'd label the edge connector and header probably P1 and P2. I then take an Excel sheet and place each net on its own row. So the first row could look like: IC1-7 IC2-7 IC3-7 IC4-10 IC5-10 C1-L C2-R P2-9 P1-17 As long as you're methodical and have marked every pin as visited, then perhaps double-check that no two nets actually comprise one larger net, you're done with the netlist. Drawing the schematic from the netlist is not difficult, and as long as you're using a schematic capture tool like KiCad, you can export a netlist to check against your original one, just to double-check. Kyle

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Schematic work needed
by Evan Koblentz 28 Aug '18

28 Aug '18

I need someone to make two (relatively simple) schematics for me. One is the IBM card for the Lego kit, and one is the Lego interface box. Here is one side of the IBM card: http://snarc.net/lego_ibm_1.jpg Here is the other side: http://snarc.net/lego_ibm_2.jpg Here's a picture of the top of the interface board: http://4.bp.blogspot.com/-DGOlTkGXj_Q/U8-T2uBG5iI/AAAAAAAAATY/7ra6gVkSKg8/s… Here's the bottom of the interface board: http://lukazi.blogspot.com/2014/07/lego-legos-first-programmable-product.ht… Here's a document Dan R. made of the board a year or two ago: http://snarc.net/9750.png Now here is the catch..... I absolutely MUST have a complete, perfect, finished schematic of the IBM card and the interface board by a week before Maker Faire -- so let's say the deadline is Friday, Sept. 14. There is no room for delay. I don't know enough about schematic-making to know if you can do it based on the above links or if you need the parts in your hand. If it's the latter, then you would need to make an appointment with me to come to the museum and do the work there. I am reluctant to mail the parts out, because I need to work with them and because if there's a delay then I have a huge problem. Who can do this? There's no pay, only glory. :) Someone already made a schematic of the Apple II card: http://lukazi.blogspot.com/2014/07/lego-legos-first-programmable-product.ht…

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Heath H11 woes
by Richard Cini 28 Aug '18

28 Aug '18

All — Last weekend I pulled my H11 off the shelf to play with it and it seems that in the 6 month is since I last used it, something happened to the power supply (it kept blowing the DC fuse). I started working on it based on the troubleshooting in the manual (replaced two transistors and a regulator) but now the AC line fuse blows and not the DC fuse. If someone has worked on these before and can let me know if there is a common failure mode, I’d appreciate it. I’m going to start from the top this weekend. There is no obvious sign of damage or failure (no smoke, busted caps, etc.). Now, if anyone has an empty DEC BA11 case (no cards; I think that would be the correct case) with a good power supply I might be in the market for one :-) Get Outlook for iOS<https://aka.ms/o0ukef>

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Apple 1 for auction next month
by Andy Meyer 28 Aug '18

28 Aug '18

Sorry if you've seen this already. (I hadn't) https://www.theregister.co.uk/2018/08/24/apple_1_up_for_sale_cassettes_incl… Andy

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Museum report
by Evan Koblentz 26 Aug '18

26 Aug '18

I was at the museum both days this weekend (stayed overnight and went for a 12-mile run on the boardwalk this morning -- fun!) We had a steady flow of visitors the whole time. Today's highlights: a father and son who spent an hour on the C-64, and a visit from our own Nick L. ... I spent time between visitors working on my Lego R2 robot, because it gives me happy memories of being 12 again!

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Re: [vcf-midatlantic] Interest in a Workshop at System Source, in Hunt Valley, MD?
by J. Alexander Jacocks 26 Aug '18

26 Aug '18

Bill, No, not yet. We only have 8 total folks across the two weekends, so far, with November being much more popular. I’m hoping for a few more. - Alex On Sun, Aug 26, 2018 at 16:56 Bill Dromgoole via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Yes, I am interested In both days at the museum. > I want to survey Bob’s Univac 1218 and Univac 490 to see what is needed to > get them lit off. > I am pretty sure that Duane is also interested in powering up the Univacs. > > Do we have any firm dates or a signup list yet? > I have both suggested dates marked on my calendar. > > Bill Dromgoole > > From: Bill Degnan via vcf-midatlantic > Sent: Monday, August 20, 2018 9:05 AM > To: vcf-midatlantic > Cc: Bill Degnan > Subject: Re: [vcf-midatlantic] Interest in a Workshop at System Source,in > Hunt Valley, MD? > > certainly if possible to have one on both weekends so everyone interested > can attend at least one. I can help more with the November workshop but > I'd probably go to both at least one day each. > > For those of you who don't know, Bob has a private museum with a ton of > computer exhibits ranging the entire spectrum of machines. the official > web site > https://museum.syssrc.com/ > > I helped Bob organize a workshop in 2014: > http://vintagecomputer.net/browse_thread.cfm?id=537 > It has been too long since we had a workshop there, I am glad someone is > taking the initiative. > > Bill > > On Mon, Aug 20, 2018 at 7:45 AM Jason Perkins via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > I'd definitely want to come. I'd think the September dates would be > better > > for me, I'm checking to be sure. > > > > On Sun, Aug 19, 2018 at 10:06 PM, J. Alexander Jacocks via > vcf-midatlantic > > < > > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > > > All, > > > > > > Since we can't have a workshop at InfoAge, this fall, I propose (along > > with > > > Bob Roswell) that we have a workshop at Bob's System Source Computer > > > Museum, in Hunt Valley, MD. > > > > > > I talked to Bob, and he and I are both available on the following > dates: > > > September 29th/30th > > > November 10th/11th > > > > > > We're not yet sure if this will be a 1-day or a 2-day workshop. Please > > let > > > me know if you are available on either of the dates, and I'll tally the > > > results. > > > > > > Thanks! > > > - Alex > > > > > > > > > > > -- > > Jason Perkins > > 313 355 0085 > > > >

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