- vcf-midatlantic - lists.vcfed.org

Need speaker assistant for VCF East 2024
by Jeffrey Brace 13 Mar '24

13 Mar '24

I need someone who will introduce speakers, move around the room to make sure the audience speaks into the microphone and walk them to the breakout room after their talk to continue questions with the audience. You don't have to do all the talks. Just what you can. I have one person so far committed to two talks. Let me know. Thanks! Jeff Brace

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Surplus Sale at Kennett Classic Update
by Bill Degnan 12 Mar '24

12 Mar '24

More hardware photos added. Sale starts March 19th 9AM. We've filled the shelves with vintage computers for sale. Just like a computer stores of old, walk in and buy a computer, ask questions and get knowledgeable answers. https://www.kennettclassic.com/surplus/ Join the kennettclassic.com mailing list to be kept up-to-date (via contact form). An update will be sent later tonight so if you want to get on the list do it soon! Proceeds benefit Kennett Classic a 501(c)(3) charity. Bill

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Kennett Classic Surplus Sale Starting Soon
by Bill Degnan 12 Mar '24

12 Mar '24

https://www.kennettclassic.com/surplus/ - this is a sampling of interesting stuff, not a complete list of all items. New things are coming in daily, as space opens on the shelves. We're ready to re-open with three rooms full of vintage computers, like an old-fashioned computer store. Walk in pick what you want off the shelf and buy it on the spot. Most items have been cleaned and tested as to their operational status. Many are fully operational or very close. Also have parts, cables, etc. OPENS OFFICIALLY 3/19, but soft open is later this week. If you want to be on the mailing list submit a contact form through kennettclassic.com Bill Degnan

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Re: [vcf-midatlantic] AT&T 6386 WGS, Olivetti 380 computer, power supply schematic needed
by CJ Reha 10 Mar '24

10 Mar '24

Something else I just thought of - your messages imply the computer was working beforehand and just recently failed. This is a dumb question, but have you checked the voltage rails on the board for shorts? I have had at least one power supply come in for repair, and work perfectly on the bench - the customer's computer had a shorted tantalum or something on the motherboard masking as a bad power supply. I've been bit that way more times than I'd like to admit as well. Regards, CJ On Sun, Mar 10, 2024 at 1:30 PM Sentrytv via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Good afternoon > > I believe I have posted before with a question about a keyboard for this > computer (386-20), > but now I have a question about a schematic diagram for the power supply. > I am looking to repair the power supply which is currently dead, outputs > about .5 V -.5 V and that’s it. > Nothing obviously open or shorted. Somebody did have their hands in it > prior to me, replacing or at least soldering various transistors. > > My issue is: > I would like to find a schematic diagram for this so that I can do > repairs myself. > Or at the very least, connect an AT power supply or hook up an ATX power > supply to get the computer running. > > I would need to know what voltages besides the obvious 12 V, 5 V , -12 V > ,-5v needed to run this system. > > If anyone has experience performing such a task, > Please contact me directly if necessary. > > I won’t bring it to the workshop unless I can find someone who knows, and > I have a schematic diagram in hand. > > Thank you > Mike Rosen > > > Sent from: > My extremely complicated, hand held electronic device. >

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Re: [vcf-midatlantic] AT&T 6386 WGS, Olivetti 380 computer, power supply schematic needed
by CJ Reha 10 Mar '24

10 Mar '24

I'm not aware of any extant schematics or service manuals for that particular machine, but I can perhaps offer some general guidance if it would be helpful to you. A lot of those PC power supplies are pretty similar in topology and I've fixed a whole crap ton of them. Question - does it try to start? As in, can you hear it go "tick" and see the fan twitch or things hooked up to it try to light up? A very common problem in this era of supply (and power supplies in general from 40yrs ago) is the output caps going bad, so the supply can't properly regulate and shuts itself down. Also, lot of them use a small value cap (maybe 47uF or so) on the primary to "kick start" the switching circuit; it commonly goes bad, and will cause a no start condition. This sometimes manifests in a situation where the supply only starts after being plugged in for a long time (leaky cap slowly charging up). The way you talk about output voltages makes me assume the fuse is probably OK and it's at least trying to do something, so hopefully no blown up switching transistors or anything that would be a bigger headache to diagnose. Let me know if this is helpful! Regards, CJ On Sun, Mar 10, 2024 at 1:30 PM Sentrytv via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Good afternoon > > I believe I have posted before with a question about a keyboard for this > computer (386-20), > but now I have a question about a schematic diagram for the power supply. > I am looking to repair the power supply which is currently dead, outputs > about .5 V -.5 V and that’s it. > Nothing obviously open or shorted. Somebody did have their hands in it > prior to me, replacing or at least soldering various transistors. > > My issue is: > I would like to find a schematic diagram for this so that I can do > repairs myself. > Or at the very least, connect an AT power supply or hook up an ATX power > supply to get the computer running. > > I would need to know what voltages besides the obvious 12 V, 5 V , -12 V > ,-5v needed to run this system. > > If anyone has experience performing such a task, > Please contact me directly if necessary. > > I won’t bring it to the workshop unless I can find someone who knows, and > I have a schematic diagram in hand. > > Thank you > Mike Rosen > > > Sent from: > My extremely complicated, hand held electronic device. >

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Hakko
by Martin A. Flynn 10 Mar '24

10 Mar '24

I was introduced to one of the engineers from Hakko and had an opportunity to talk up CDL, VCF, and to a lesser degree InfoAge (IE the five minute elevator speech that we all should be ready for) Out of that conversation: So, are there any legacy chips that CDL does not have hot air rework nozzles for ? Martin Flynn

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Not quite O/T....
by Martin A. Flynn 10 Mar '24

10 Mar '24

Background: With the approval of InfoAge management, CDL and it's friends have successful applied for an LPFM license for Camp Evans. The new station is WALL-LP, and will be found at 103.9 MHz To support this, CDL has acquired all of the hardware, including the transmitter, EAS decoder, and a broadcast phone system. We have built a gateway using audiocodes hardware to convert the existing SIP trunking to ISDN-BRI to support the broadcast phone system. So if you want to demo those Livingston Portmasters or other ISDN kit at VCF-E , CDL has the tech you need. Martin

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AT&T 6386 WGS, Olivetti 380 computer, power supply schematic needed
by Sentrytv 10 Mar '24

10 Mar '24

Good afternoon I believe I have posted before with a question about a keyboard for this computer (386-20), but now I have a question about a schematic diagram for the power supply. I am looking to repair the power supply which is currently dead, outputs about .5 V -.5 V and that’s it. Nothing obviously open or shorted. Somebody did have their hands in it prior to me, replacing or at least soldering various transistors. My issue is: I would like to find a schematic diagram for this so that I can do repairs myself. Or at the very least, connect an AT power supply or hook up an ATX power supply to get the computer running. I would need to know what voltages besides the obvious 12 V, 5 V , -12 V ,-5v needed to run this system. If anyone has experience performing such a task, Please contact me directly if necessary. I won’t bring it to the workshop unless I can find someone who knows, and I have a schematic diagram in hand. Thank you Mike Rosen Sent from: My extremely complicated, hand held electronic device.

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Museum: PDP-8 and beyond. Come see it at VCF East
by Douglas Crawford 10 Mar '24

10 Mar '24

THANKS SO MUCH Dave Gesswein for coming to the repair event and lending your PDP-8 expertise to us again for the weekend! The progress you made this weekend is so exciting and encouraging. For those fairly new to VCF MidAtlantic, our Straight-8 has local NJ history with the The Resistors (google it) and came to use in "barn storage" condition. Dave massively restored this machine and continues to lovingly keep it going. These fault discoveries and repairs are wonderful as we leverage this machine pretty hard as the machine is the oldest computer that we can demonstrate at-will anytime in the museum. It's one of two that we can show how front panels work- the other is the HP 1000 minicomputer. Its the only one in octal. (The UNIVAC 1219 is only demo'd at special events.) We now have several demonstration options on the PDP-8: - A "cylon" mode light demo - Create a message on ASR 33 paper tape in readable font - Math demo on the ASR 33 TTY - Music played to a transistor radio via EMI. - Loading a program from paper tape. The programs, including the tape loader, are kept in core memory. Great stuff! We are now trying to decide to demo with the A/D board. There are more plans for DEC restorations in the near term including a 8e & PDP-11 restorations on the short term. These are likely going to run even more impressive demos. On the longer term we'll have much more DEC in the bigger museum space. A year has been spent researching and putting in place thoughtfully selected and documented software demos on all the working microcomputers. This pushing us towards an all new museum experience as we become a "must see" computing history location on the east coast for the general public, STEM, technology college students, and tech industry professional visitors. -- Douglas Crawford VCF Mid-Atlantic Museum Mgr InfoAge Science & History Museums 2201 Marconi Road Wall, NJ 07719

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Workshop results
by David Gesswein 10 Mar '24

10 Mar '24

Worked on straight 8. Reported problem was toggled in RIM loader wouldn't load the BIN loader tape. Verified issue was still occurring. Since we knew we had issues with connection to cards from last workshop cleaned all the processor cards edge fingers and backplane connector using paper/paper towel with contact cleaner. Battled them during restoration of the machine was 9 years ago due to storage conditions. Didn't change symptoms so single stepped through the loader. Found the RTL (Rotate Twice Left) instruction didn't do anything. Traced it to bad transistor in R603 pulse amplifier in PB19. With transistor replaced and after figuring out I loaded the paper tape backwards the machine worked. Processor sensitivity to motion seemed fixed and running finger down cards also didn't cause crash. Memory side was still sensitive so cleaned those also. Luck didn't hold so memory was non functional after cleaning. Tracing signals with scope found timing pulses missing from W300 delay line board. Inspection found cracked solder joints on both of the board. The delay lines are too tall so get pulled on when inserting or removing boards. Think that cracked joints were present and got worse when cards removed for cleaning. After resoldering Still not working. More probing and found one signal for write was not being generated. Inspected transistors on the W300 generating it and noticed one transistor lead was all rusty. Poked it and it disintegrated. With transistor replaced machine now worked. Ran diagnostic set and reloaded demos and declared ready to go. Hopefully the problems on the W300 was causing some of the occasional flaky behavior. All board cleaned except sense amplifier boards that had additional connections. Verified moving them didn't cause crashes. The boards plugged into the memory box also weren't cleaned since they are gold to gold. Also didn't clean front panel cable boards. If I was able to accurate count that high I cleaned 227 edge and backplane connectors. Each has 18 contacts. We discussed enabling the 12 bit A/D that was installed in the machine when we got it. My memory was that wire(s) needed to be removed from the backplane to enable when I looked at it years ago. Maintenance manual says only cards need to be installed. Decision was to get it working removing wires if needed but I finished work on machine at 4pm Sunday so decided not a good time to mess further. A/D can convert with 6 to 12 bits accuracy taking 7.6 to 56.6 microseconds. Input is 0 to -10V. We discussed some what demo to use that would be of interest to the public but not too gimmicky. Still thinking about it. Have Teletype where we can print results or text graph.

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