test-drb July 2000

test-drb@ccmp.vtda.org

155 participants
521 discussions

CCC (was Re: Announcing... Rent a wreck)

by ethan_dicks＠yahoo.com

--- Chuck McManis <cmcmanis(a)mcmanis.com> wrote: > Of course what we've missed is that the cost of shipping of _us_ is > relatively constant. True, but more than some boxes. > The answer then suggests itself, what we need is "Classic Computer Camp." > > We find some very cheap land somewhere that has relatively easy air access > (somewhere in New Mexico perhaps) and we build a camp. At the camp we have > a bunch of buildings with computers in them and a dorm. Enthusiasts from > all over the world can fly to the camp, and for a modest fee, spend as much > time as they can afford tinkering with all kinds of classic computers. If > it was a self sustaining operation I'd suggest we convince Tony to relocate > to be in charge of the camp, that way he could be employed at a job where > all day all he had to do was tinker with and fix old computers and talk to > people about how they worked while they tinkered with them and fixed them. > > This solves a number of problems: > 1) Cost effective storage (since you can get 50 acres in New > Mexico for $25,000 easy) > 2) People get to play with the computers, they don't have to deal > with the outside world. > 3) The assortment could be much larger (even "big" iron!) > 4) We enough lead time it would be cost effective to travel there. > > I suspect several people would be more than happy to contribute large > numbers of computers to this effort. Well... I already have 32 acres and a quonset hut. I have plans to add a large building (40'x60' nominally) next door to it, but I'd have to upgrade my electrical service first. I'm in Columbus, OH, a few minutes away from Port Columbus with direct service from most major hubs (Chicago, NYC, DFW, Atlanta, DC, St. Louis, Phoenix). I'm 8 hours or less by car from Toronto, Pittsburg, DC, St Louis, Chicago, Nashville (I think), and a host of other places. Benefits: Well located for midwest and East Coast users (especially me ;-) Land already grabbed Zoned Rural, not Residential (a "library" is an acceptable use) Well stocked with VAXen on down. Drawbacks: Colder than N.M., therefore higher operating costs (heat, etc.) Smaller than 50 acres. Far from West Coast Users. I have this 501c3 Museum project that I've been working on for a while, but frankly, I'm kinda stalled out at the name phase. I have the necessary number of enthusiastic bodies to incorporate non-profit in Ohio (three), all I really need to do is pick a name, finish off the articles of incorporation and pay the filing fee. It's easy to self-serve an Ohio corp; it's the second best state next to Delaware. At least in the non-winter months, it'd be easy to provide camping-style accomodations (including parking for RV, for those so inclined). Actual housing is another level of expense, no matter what the location. It's certainly an interesting concept. Actual implementation is another matter entirely. Classic Computer Camp or no, my 10-year-plans are to stick up a suitable building for my own uses. Finding a way for the construction and operation to be even partially funded would be a bonus. -ethan ===== Even though my old e-mail address is no longer going to vanish, please note my new public address: erd(a)iname.com The original webpage address is still going away. The permanent home is: http://penguincentral.com/ See http://ohio.voyager.net/ for details. __________________________________________________ Do You Yahoo!? Get Yahoo! Mail - Free email you can access from anywhere! http://mail.yahoo.com/

24 years, 4 months

Switching PSU Theory of Operation / Repair Tips & Techniques

by dhquebbeman＠theestopinalgroup.com

[..snippage..] > > No, if I measure across the positive and negative, I'm seeing nearly 600vdc. > > Eeek!. That's double what I'd have expected. Does this thing run off the > normal 115V mains, or 220V? How does it (effectively) quadruple the mains > input? [..more snippage..] > > : switcher, which runs the 280V DC through the torroidal transformers to > > : produce the other voltages. The Big Bridge is to convert the output of the > > That's more what I'd have expected. About 300V supply to the chopper > stage, not 600V. > > Can I ask a silly question? Are you sure you're reading the voltmeter > correctly. You've not got a 'range doubler' turned on or something (I've > been caught by this one...) You may not have yet seen the correction I posted, but I was seeing that only when I measured the + terminal of one of the blue electrolytics, and the - terminal of the other. Why would I do that? I'd just gotten out of bed and hadn't had coffee yet. YES, A BAD TIME TO MESS WITH HT! After I saw that I realized my time would be better spent letting the dog out and preparing to leave for the office rather than risking my life while I was still half asleep. No more messing with it except when alert, I promise! > > > ****PAGING TONY DUELL**** > > Did you honestly think I'd not reply to a question like this :-). Be sure to check the quote level to see that this wasn't me who said it. > > I can probably sketch the HT portion out, but this PSU includes two rather > > complex looking boards (although they're only 2-layer) with custom PALs and > > the like. > > PALs? Are you sure? It's not at all common to have significant amount of > digital electronics in an SMPSU. Most of the time it's either simple > analogue circuitry either as discrete components, or one of the well-know > SMPUS control chips. These look like digital boards to me. I'll pull 'em and either scan them or take a digital photo, as well as record a few part numbers. Keep in mind that being overly proprietary was one of the things that killed Prime. > > One symptom I hope leads me to finding the problem is that the PSU has > > four LEDs onit, 3 green, 1 yellow, the green are status indicators for > > +5, +12, & -12; the yellow LED is an indicator for the AC. Although the > > AC feed to the PSU is fine, the yellow LED glows dimly, not brightly, as > > it once did. The green LEDs are unlit. > > That's a starting point. Trace back from that 'AC' LED to find what it's > really monitoring. Maybe that supply line is low. > > > That suggests that the mains rectifier is still functional, they don't > > > 'chop' the ac mains. > > > > Uh, being an analog idiot, forgive me if this is a stupid remark, but > > I thought "chopping" the AC with a rectifier yielded DC; when I measured > > No. 'Rectifying' is turning AC into DC. 'Chopping' is turning that DC > back into a square wave (at least in voltage, as I mentioned last night, > the current waveform is complex). Ok. I thought chopping referred to the way the waveform looks before vs. after. Before it's a sine wave, crests about and below the axis. After being rectified, there are only crests above the axis. That looks like chopping off the bottom part of the wave to me. Sorry. > > If it matters, the room in which I keep the Prime was hotter than > > I usually let it get when I have the Prime running (I don't have > > central A/C, so I have a window unit in an adjacent bedroom and > > In which case look for dried-up (high ESR) electrolytic capacitors. This > is a very common heat-related problem. Would I not have to open them to make that determination? I though they contained PCBs or somesuch toxic chemical. regards, -doug q

24 years, 4 months

Using WD40 on a Remote Services Consoles

by jfoust＠threedee.com

WD40 is a pretty good fire starter. - John

24 years, 4 months

Switching PSU Theory of Operation / Repair Tips & Techniques

by dhquebbeman＠theestopinalgroup.com

Geoff Roberts stated thusly: > This is starting to sound like it has either a separate + and - supplies with a common ground, or > it's some kind of voltage doubler. Since I can't imagine why they'd need to do a doubling act > for the primary side of a SMPS I'm inclined to suspect the former. Here's a quote from a former Prime engineer (who's been as helpful as his memory permits): : These things are much more complicated than that. Functionally the Line is : directly connected to a special rectifier configuration called a voltage : doubler. It produces rougly 280 volts DC. There is no isolation transformer, : which makes these things potentially lethal. The 280V DC is input to : switcher, which runs the 280V DC through the torroidal transformers to : produce the other voltages. The Big Bridge is to convert the output of the : switch from high frequency (probably about 25Khz) AC to DC. Howwver, your former remark would also seem to be true, as the two rectifer outputs are +280vdc and -280vdc, respectively. [..snippage..] > > Yes, but aren't the 2 capactiors in series, something like : > > > > ------------+-------------------- +ve > > | > > ===== > > ----- > > | > > ------------+ > > | > > ===== > > ----- > > | > > ------------+--------------------- -ve > > Well they could be if they were across a potential higher than the invidual voltage rating of the caps. > That gives you an effective voltage rating equal to the sum of the ratings of the caps. The penalty is > that it divides the effective capacitance by the number of caps in the series circuit (assuming all are the > same value - it's a bit more complex if they have different values) Have you got a + where there should be -? > The above diagram looks wrong to me. If this was a +/- supply, then the lower cap should have it's anode > connected to the common (centre) ground point, or it's effectively reverse polarised. It would be more > common to find caps in parallel to increase the capacitance (opposite of series - the total c of the > circuit is equal to the sum of the values of all the caps in it.) > > > And you're seeing 600V between the 2 points I've marked '+ve' and '-ve', > > right? That's still twice what I'd have expected -- I'd expect peak mains > > voltage (i.e. 115*sqrt(2)) across each capacitor, or about 320V between > > +ve and -ve in that diagram. > > The Prime techie mentioned a bridge, so I assume it's not a doubler circuit, > that leaves some kind of +/- supply but I'm blowed if I know how they achieve that > out of a bridge. I'd definitely like to see a circuit for this one. > > > I am still puzzled as to how it gets 600V without either other large > > capacitors, or a mains-frequency transformer. > > Ditto. --------------------- + to BBU | | +---------{ MCI 307138 }---------------+-------------------- +ve / \ | + | / \ ===== / 12k ohm / \ ----- \ 5% / \ | - / ----* *---------------------------------+----------* | \ /| | + \ | \ / | ===== / 12k ohm | \ / | ----- \ 5% | \ / | | - | | ----------{ MCI 307138 }---------------+--------------------- -ve | | | | | | | | ---------------------- - to BBU | | | | | | 115v Load 115v Neutral > > I will just ask again -- this thing does run off 115V, right? > > I keep wondering the same thing, if it was multiphase it might make sense, hmmm, > I *wonder* if this was originally 3 phase and been converted to single? > 2 mains rectifiers in series? With a common rail? Sounds ugly but possible I suppose. There is an adhesive label on the front of the PSU that says "115 V". Since it's a removable label, that there is some way to change it over for 230v operation. With that in mind, I can report that there is a connector on the main PCB that has wires that loop back to itself. I'm wondering if it's replaced with a plug either without wires or with wires in a different configuration that it changes the PSU from accepting 115v input to 230v input. But about phases, I am very ignorant. [..snip-o-rooney..] > > > > PALs? Are you sure? It's not at all common to have significant amount of > > > > digital electronics in an SMPSU. Most of the time it's either simple > > > > analogue circuitry either as discrete components, or one of the well-know > > > > SMPUS control chips. > > How old is this box of tricks anyway? I must agree, if there is a lot of logic there, > from the description of all the led monitoring etc, it might be more to do with that than > part of the supply proper. Possibly control logic to ensure the system won't power > up if the supplies are out of spec, or shutdown the whole thing if one fails etc... I think this is correct. > > > > In which case look for dried-up (high ESR) electrolytic capacitors. This > > > > is a very common heat-related problem. > > Indeed. Probably the commonest fault in PSU's, which tend to get pretty hot > anyway. The startup resistor is still a potential culprit here too. Geoff, see my other post which is a reply to the same message to which you were replying in this message to which I was replying. [hope that's clear!] regards, -doug quebbeman

24 years, 4 months

Using WD40 on a Remote Services Consoles

by ethan_dicks＠yahoo.com

--- Eric Smith <eric(a)brouhaha.com> wrote: > I know nothing about the standalone RDC box that's been discussed earlier. > But the 11/70 didn't use that. It used a replacement front panel (without > the usual switches and lights) and a Unibus board. IIRC, it was called > a KY11-R. That's what I've got. :-( I would love to have switches and lights on an 11/70 but I doubt I'll ever find an affordable older panel. -ethan ===== Even though my old e-mail address is no longer going to vanish, please note my new public address: erd(a)iname.com The original webpage address is still going away. The permanent home is: http://penguincentral.com/ See http://ohio.voyager.net/ for details. __________________________________________________ Do You Yahoo!? Get Yahoo! Mail - Free email you can access from anywhere! http://mail.yahoo.com/

24 years, 4 months

Using WD40 on a Remote Services Consoles

by cmcmanis＠mcmanis.com

Ok, I'm completely baffled. Is there some sort of conspiracy afoot to not discuss how the DEC remote services console works or is used? I know that there are ex-DEC field service types here and certainly ex-Digits who should know the basics. And yet at least three times over the last 2 years theses questions have come up and been left hanging with absolutely no information. Whazzup wit' dat? I happen to have a use for mine that is exactly what was intended, I've got a VAX 4000/300 sitting at my office that I'd like to be able to dial into the console and reset and reboot. I don't have a spare serial port on a PC to use and it would be "cool" to do it with this piece of vintage gear that was designed to do this. Yes, I know these things were originally DEC proprietary and secret stuff but heck DEC is dead. We've got to keep this information alive, not let Compaq take it to the grave with them. --Chuck

24 years, 4 months

Announcing... Rent a wreck

by ethan_dicks＠yahoo.com

--- Mike <dogas(a)leading.net> wrote: > Cool. I had a few encouraging replys. Here's the first list of available > stuff... > > 14. OSI CIII *There*'s one I'd consider renting. The shipping would be a killer. I had a family friend when I was a kid that had one of these at home. ISTR it was around $8-$10K, loaded. I did some BASIC and assembler on the 6502 side. > 21. Kim-1, Kim-4, TVT, etc... Cool... I happen to have a TVT that I've never powered on. I built it as a kid and never got the 6502 SBC to hook it up to. > 44. Cosmac ELF-II > 45. Cosmac SuperElf I'd love to play with these, too. I have just about every other 1802 box of the era, including the Radio Shack video game (supposedly upgradable to a full computer) and a VIP terminal. What are your terms? Would you consider "payment in kind" in the form of an equipment exchange? Also... consider writing up a formal contract that spells out rights and responsibilities, especially for loss or damage. I'm not so much concerned that the people on this list will try and rip you off, but if an insurance claim ever needs to be filed due to fire, theft, etc., the renter's insurance company will be more likely to honor the claim if there's a paper trail establishing liability (take it from someone who has had to seek coverage of stolen classic computers - two PETs and an Amiga). -ethan ===== Even though my old e-mail address is no longer going to vanish, please note my new public address: erd(a)iname.com The original webpage address is still going away. The permanent home is: http://penguincentral.com/ See http://ohio.voyager.net/ for details. __________________________________________________ Do You Yahoo!? Get Yahoo! Mail - Free email you can access from anywhere! http://mail.yahoo.com/

24 years, 4 months

Creating Schematics for Old Computer Circuitry: CAD Freeware

by dhquebbeman＠theestopinalgroup.com

Well, I seriously doubt I'd end up want to CAD an entire PSU, but habing to struggle making an ASCII art schematic this morning got me thinking about CAD freeware again. I work for an architectural firm, and have AutoCAD installed on my workstation, but I don't have a symbol library of electronic parts, so I haven't bothered trying to use it for electronics. I do have PADS*PCB, which is available as either a commercial product or as crippleware (something like 60 components). I was just starting to get pretty gppd with it when I had to shelve the project I was working on for work that had regular paychecks. Does anyone know of/use a freeware CAD program for producing moderately-complex schematics? Something a bit less than what you'd need to create the typical modern PC motherboard (although VLSI seems to have taken some of the complexity load off the motherboards)? I really don't even need PCB component layout or autorouting, just a nice schematic program. tia, -doug quebbeman

24 years, 4 months

OSI model 600 find

by mranalog＠home.com

Bill Sudbrink said: > > The main board says: > > "Ohio Scientific Model 600 CPU @1978 Rev B" > > I can give you full schematics for this guy. I've got the > SAMs. I'm in no hurry. Thanks for the offer, but you just finished supplying me with all that documentation on the C4P. Someone just down the street from me says he has documentation and schematics for the mother board. I'll check that out first. He also pointed me to a couple of great Compukit 101 pages: http://www.compukit.org/ http://www.home-micros.freeserve.co.uk/uk101/uk101.html > > The small daughter board contains three 2716s labeled > > "REV 94 I", "REV 94 II", and "REV 94 III". > > I think that's an Aardvark board too... no idea what's on the > EPROMs though... Looking closer, there are sockets on the mother board for 8 pairs of 2114s. There is one pair of 2114s in the first pair of sockets and one pair of 2114s in the last pair of sockets. It looks like the select lines for the 6 pairs of sockets inbetween are wired to these 2716s. So it has the feel of some kind if firmware application. Joe <rigdonj(a)intellistar.net> said: > Wifes, they just don't understand. My wife wants my HP 9845 and 9895 >dual 8" drives out of the kitchen. I have no idea why :-) If she didn't understand, then the drives never would have made it to the kitchen. I'm sure she just wants to make sure she doesn't stumble into the kitchen one morning and stick a Pop-Tart into one of your drives. In your house there is a path through the garage, a path through the living room, a path through the dining room, and one bedroom that I can just look into. My wife just wants a corner in the dining room to set-up a trendmill. --Doug ==================================================== Doug Coward dcoward(a)pressstart.com (work) Sr. Software Eng. mranalog(a)home.com (home) Press Start Inc. http://www.pressstart.com Sunnyvale,CA Curator Analog Computer Museum and History Center http://www.best.com/~dcoward/analog ====================================================

24 years, 4 months

Using WD40 on a Remote Services Consoles

by dhquebbeman＠theestopinalgroup.com

> > WD40 is a pretty good fire starter. > Don't know about fire per se, but on this list, it's certainly started a flame or two... 8D

24 years, 4 months

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test-drb July 2000