RE: DEC RF30 Integrated Storage Element Service Guide
Can anyone help me to understand why all my RF30 disks report the same diagnostic code 0x300B? Thanks Rob > -Original Message- > From: Rob Jarratt > Sent: 23 December 2021 17:46 > To: r...@jarratt.me.uk; 'Rob Jarratt' ; 'General > Discussion: On-Topic and Off-Topic Posts' > Subject: RE: DEC RF30 Integrated Storage Element Service Guide > > I have tried three different RF30 disks, two of them from one source and one > from a completely different source, so completely different histories. They > all give me the same diagnostic error code, 0x300B, which seems to be too > much of a coincidence, so I think it may be something in my configuration. > > I am using a MicroVAX 3800 (KA655 with KFQSA). When I power on, the fault > light comes on and then goes out after a while. This I believe is normal > behaviour. However, as soon as I try to access the disk (e.g. SHOW DEVICES > in the console firmware) the fault light come on and when I boot to VMS > (from a different disk), VMS can't see the drive. > > I thought it might be some kind of DSSI ID conflict because I have an RF72 in > the machine at ID 0. Removing the RF72 does not change the behaviour. > Installing an ID=0 plug on the RF30 does not change the behaviour. I set the > DIP switches on the RF30s to have an ID=1 and still it doesn't work and > PARAMS reports UNITNUM=0. I followed this page > http://mcmanis.com/chuck/computers/vaxen/dssi-plug.html but it didn't > work: > > PARAMS> sho /mscp > > Parameter Current DefaultType Radix > - - > MSCPNVR 2020202020202020 2020202020202020 > 2020202020202020 2020202020202020 > 2020202020202020 2020202020202020 > 2020202020202020 2020202020202020StringHex RO > UNITID1502401193918703 0 QuadwordHex RO > ALLCLASS 0 0 ByteDec B > MEDIAID 2264601E 2264601E LongwordHex RO U > UNITNUM 0 0 WordDec U > FIVEDIME 1 1 Boolean0/1 B > FORCEUNI 1 1 Boolean0/1 U > FORCECID 1 1 Boolean0/1 RO > CNT_TMO 6060 WordDec RO > > PARAMS> set unitnum 1 > > PARAMS> set forceuni 0 > > PARAMS> write > Failed to acquire unit, cannot WRITE > > Am I doing something wrong? > > Thanks > > Rob > > > -Original Message- > > From: cctalk On Behalf Of Rob Jarratt > > via cctalk > > Sent: 23 December 2021 09:45 > > To: 'General Discussion: On-Topic and Off-Topic Posts' > > > > Subject: RE: DEC RF30 Integrated Storage Element Service Guide > > > > I wonder if anyone knows what diagnostic code 300B means? > > > > >>>set host/dup/uqssp/disk 2 params > > PARAMS> status config > > > > Configuration: > > Node DIA0 is an RF30 controller > > Software RFX V103 built on 5-MAY-1989 13:18:42 > > Electronics module name is EN94019334 > > Unit is inoperative, error code 300B(X) > > Last known unit failure code 300B(X) > > In 60233 power-on hours, power has cycled 189 times > > System time is 5-MAY-1989 13:19:46 > > > > Regards > > > > Rob > > > > > -Original Message- > > > From: cctalk On Behalf Of Rob > > > Jarratt via cctalk > > > Sent: 22 December 2021 15:59 > > > To: General Discussion: On-Topic and Off-Topic Posts > > > > > > Subject: DEC RF30 Integrated Storage Element Service Guide > > > > > > I am looking for the service guide for the RF30 DSSI disk. It is not > > > on > > Manx and > > > not on BitSavers. Does anyone know of a copy? The part number is > > > apparently EK-RF30D-SV. > > > > > > > > > > > > Thanks > > > > > > > > > > > > Rob
Re: VAX 780 on eBay
On 1/1/22 2:00 PM, Chris Zach via cctalk wrote: This is wise, but 240v is quite nice for computer equipment. I had an electrician run a 240v 30a (10g wire) circuit out to my work shed, where a subpanel is installed with 120v 15a and 240v 15a circuits for the equipment. I had two 120v 20A circuits, one on each leg of the 120v/240v residential feed, run to my computer equipment in the house I sold a few years ago. I'd like to have the same again once I finally set things up the way that I want to. I'd really like 3ɸ at home for a number of different things. That would allow me to run computer equipment at 208v which, as I understand it, is more efficient than 120v. I don't think anything I do would actually /need/ 240v. I'd also like 3ɸ for other things in the house, namely wood working tools. 240 just allows you to get twice the power to the device using the same size wire (14g for 15a for example). Ya. One might wonder why higher voltage means that you can get twice the power (wattage) to something. But that's where the fact that most wire used for 120v circuits is rated for up to 250v which means that the same wire can safely carry 240v. Hence how you can get twice the power by doubling the voltage. But modern switching computer supplies are more efficient at 240v than 120v so you waste less power. Do you have something that you can point to as reference? Where does 208v compare to 240v / 120v? 120 is good for like light bulbs and stuff. Drawing over say 10a continuous at 120 will pretty much burn up sockets and such in short order. It depends on the quality of the socket. My understanding is that a NEMA 5-15 is rated to sustain 15A at 120V indefinitely. Then there are NEMA 5-20s which are rated for 20A. So ... over 10A continuous seems quite possible if not expected with some installations. -- Grant. . . . unix || die
Re: What is a BC01-R
On Sat, Jan 1, 2022, 7:03 PM Nigel Johnson Ham via cctalk < cctalk@classiccmp.org> wrote: > Found here: > > http://www.pdp8online.com/bklatt/43.jpg https://www.vintagecomputer.net/browse_thread.cfm?id=249 Bill > >
Re: What is a BC01-R
Found here: http://www.pdp8online.com/bklatt/43.jpg Digital Cables Handbook Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU Amateur Radio, the origin of the open-source concept! Skype: tilbury2591nw.john...@ieee.org On 2022-01-01 18:52, Ethan Dicks via cctalk wrote: On Sat, Jan 1, 2022 at 6:40 PM Chris Zach via cctalk wrote: Regardless, I found a M857 board with a RS232 cable on it and BC01R-25 on it. Was that for a pdp11/05 by chance? I found this reference from the Cables Handbook. Sounds like it was a generic cable that probably worked with several devices. http://www.pdp8online.com/bklatt/43.jpg My recollection was that the PDP-11/05 had a special 40-pin Berg connector off the backplane for the integrated Console SLU. -ethan
Re: What is a BC01-R
On Sat, Jan 1, 2022 at 6:40 PM Chris Zach via cctalk wrote: > Regardless, I found a M857 board with a RS232 cable on it and BC01R-25 > on it. Was that for a pdp11/05 by chance? I found this reference from the Cables Handbook. Sounds like it was a generic cable that probably worked with several devices. http://www.pdp8online.com/bklatt/43.jpg My recollection was that the PDP-11/05 had a special 40-pin Berg connector off the backplane for the integrated Console SLU. -ethan
What is a BC01-R
Quick question: I'm going through my old cables looking for the paddle interface for the Current loop for my pdp8/L. I thought I saved one from my old pdp8/I, maybe not. Regardless, I found a M857 board with a RS232 cable on it and BC01R-25 on it. Was that for a pdp11/05 by chance? Oddly enough I also found the interface adapter that goes into my VT52 to support 20ma current loop devices. I currently use the VT52 as an RS232 console for my pdp11, but still, Wow.
Re: VAX 780 on eBay
On 1/1/22 2:44 PM, Guy Dunphy via cctalk wrote: The 'installation and configuration' manual for this machine would be huge. They don't have it. On bitsavers. I just paged through it to check power consumption. Plus, it's a mainframe. Not even any blinkenlights. Without setting it up as a complete system with everything interconnected properly, how would you even know it was running correctly? Well, you need to hook up a serial console terminal, and the console floppy needs to work. That has power-up self tests, which will be quite helpful in the beginning. Then, there would be a diagnostic tape that could run further detailed tests. Plus you can safely assume at least some of the system unit interconnect cables are missing. These should all be in the manuals on bitsavers. I'm pretty sure they have the complete /780 print set, which was 11x17" and about 2" thick! Potentially weeks, even months of restoration work for a buyer, before even daring to apply power. Then if there's anything wrong in the electronics, good luck diagnosing and getting spare parts. Yes, getting a copy of the diags tape would be hugely helpful, but probably somebody has that. Jon
Re: VAX 780 on eBay
On 1/1/22 3:19 PM, Josh Dersch via cctalk wrote: For clarification -- the 11/780 is not liquid cooled. The seller mixed up some photos between the TU77 listing and the 11/780 listing (the TU77 listing has photos of the 11/780's backplane in it just to make things more fun). Agreed on all other counts, though, powering this thing up blindly is a dumb idea. Right! The cooling gear on the back of the TU77 is to cool the bearing air, to keep from melting the tape. We had nasty tape sticking when running backups with our original TU77. DEC told us about the problem and advised to open the cabinet back door when running the drive for long periods. Then, they installed a mod kit with the extra tubes and radiator and additional fans, and that solved the issue. The VAX 11/780 is most certainly air-cooled, but does have impressive centrifugal blowers shooting vast quantities of air out the back. Watch out, women with short skirts, when you walk behind the CPU! DEC apparently designed a liquid-cooled VAX code-named Aquarius, but it was never fielded. A later air-cooled version was called Aridus. Jon
Re: VAX 780 on eBay
On 1/1/22 2:35 PM, ben via cctalk wrote: On 2022-01-01 12:36 p.m., Jon Elson via cctalk wrote: On 1/1/22 1:11 PM, Bill Gunshannon via cctalk wrote: Just out of curiosity, how much current is needed for an 11/780? Depending on options, the CPU cabinet would draw about 10-12 A per line, 3-Phase 208 V. And, that is on the upper end of the range. Starting surge would be a lot more, of course. Jon How much power is used for memory and hard drives? memory power was provided by the row of power supplies below the CPU cards as seen in the pics. Memory power on the /780 was pretty insignificant, as that system didn't have large memories. The original /780 had 256 KB memory cards, I think the one in the current sale has the newer memory system with 1 MB/card. Hard drive power was QUITE substantial, the bigger drives had pretty big 3 phase motors to spin the big disk packs/HDA's. Jon
Re: VAX 780 on eBay
> On Jan 1, 2022, at 4:19 PM, Josh Dersch via cctalk > wrote: > > On Sat, Jan 1, 2022 at 12:47 PM Guy Dunphy via cctalk > wrote: > >> ... >> But you're all focussed on that, and missing another important detail. The >> machine has a liquid cooling system. >> ... > > For clarification -- the 11/780 is not liquid cooled. Correct. Did DEC make any liquid cooled machines? There was a large VAX which was going to be, code-named Aquarius, but I think they canceled that one and redid the design to be air-cooled, codename Aridus. That's the VAX 9000 if I remember right. paul
Re: VAX 780 on eBay
On Sat, Jan 1, 2022 at 12:47 PM Guy Dunphy via cctalk wrote: > At 07:50 PM 1/01/2022 +, you wrote: > >> > >True. But if you're trying to get > $5000 for something, it doesn't seem > unreasonable to suggest that investing a bit in getting an extension cord > run to the location of the machine would be a good idea. The absence of > that effort makes me wonder if the owner knows what the outcome of such a > test would be and doesn't want to have to report it. > >> > > > >But what would that accomplish? I think testing something like this > requires a lot more effort than plugging it in and hitting the circuit > breaker. To test this to see if some ODT comes up probably requires quite a > lot of effort (locate a terminal/pc, wire it up, figure out where to plug > it into the 780, etc. If this guy is a bulk dealer I would be surprised if > he has the knowledge to do anything more than a power test which, again, > would not be very useful and could even be detrimental. > > > Exactly. The machine has a 3-phase 208/240V plug, they don't have such an > outlet. Their efforts stop right there. > > But you're all focussed on that, and missing another important detail. The > machine has a liquid cooling system. > Some of the hoses look like they are Tygon, in the age-decayed brittle > stage. Touch them and they crumble away. > Running the machine without cooling would utterly wreck it. Even if they > solved the mains power problem, > they would be very unwise to actually power it up. > For clarification -- the 11/780 is not liquid cooled. The seller mixed up some photos between the TU77 listing and the 11/780 listing (the TU77 listing has photos of the 11/780's backplane in it just to make things more fun). Agreed on all other counts, though, powering this thing up blindly is a dumb idea. - Josh
Re: VAX 780 on eBay
On 1/1/22 10:40 AM, Paul Koning via cctalk wrote: On Jan 1, 2022, at 1:12 PM, Noel Chiappa via cctalk wrote: This: https://www.ebay.com/itm/275084268137 The starting price is expensive, but probably not utterly unreasonable, given that: - the 780 was the first VAX, and thus historically important - 780's are incredibly rare; this is the first one I recall seeing for sale in the classic computer era (versus several -11/70's, /40s, etc) - this one appears to be reasonably complete; no idea if all the key CPU boards are included, but it's things like the backplane, etc (all of which seem to be there) which would be completely impossible to find now - if any boards _are_ missing, there's at least the _hope_ that they can be located (780 boards seem to come by every so often on eBait), since people seem to keep boards, not realizing that without the other bits they are useless Interesting, but the argument for why it's not tested is implausible which makes me very suspicious. I suppose there might be a few American homes that have only 110 volt power, but I'm hard pressed to think of any I have ever seen, and that includes really old houses. Without replacing the power controller in the 11/780, you need 208v 3-phase to run it. It's not impossible...nothing in the CPU actually *needs* 3-phase as the individual power supplies are 120v but the overall maximum load is greater than a 30A 120v circuit. TTFN - Guy
Re: VAX 780 on eBay
In my current house I have done 240V/50A wiring, 240V/50A Sub Panel, lots of 240V/30A outlets. None of which I would advise the usual amateur to do. :-) This is wise, but 240v is quite nice for computer equipment. I had an electrician run a 240v 30a (10g wire) circuit out to my work shed, where a subpanel is installed with 120v 15a and 240v 15a circuits for the equipment. 240 just allows you to get twice the power to the device using the same size wire (14g for 15a for example). But modern switching computer supplies are more efficient at 240v than 120v so you waste less power. 120 is good for like light bulbs and stuff. Drawing over say 10a continuous at 120 will pretty much burn up sockets and such in short order.
Re: VAX 780 on eBay
The TU77 has a 3ɸ power plug on it. That probably explains why testing it would be problematic in a residential settings. A TU77 can run on household 240v. If I recall it used the 240 for the big blower motor and the rest of the stuff ran on 110. 1ɸ240V is vastly different than 3ɸ120/208V. 1 phase 240 is just 2 120 volts out of phase. Looking at the 780 it has 3-5 power supplies in it, each one running on 120v. My guess is the main fan blower is 3 phase 208, and each of the power supplies is run off a 208-common leg (giving 120v). Big ole monster, but if you can put a 240v motor on the blower you should be able to rewire it to run on a couple of household 240 circuits. C (Ran a KS10, TU77, and 2 RM03's in a spare bedroom once. It has... upgraded wiring)
RE: VAX 780 on eBay
At 07:50 PM 1/01/2022 +, you wrote: >> >True. But if you're trying to get > $5000 for something, it doesn't seem >unreasonable to suggest that investing a bit in getting an extension cord run >to the location of the machine would be a good idea. The absence of that >effort makes me wonder if the owner knows what the outcome of such a test >would be and doesn't want to have to report it. >> > >But what would that accomplish? I think testing something like this requires a >lot more effort than plugging it in and hitting the circuit breaker. To test >this to see if some ODT comes up probably requires quite a lot of effort >(locate a terminal/pc, wire it up, figure out where to plug it into the 780, >etc. If this guy is a bulk dealer I would be surprised if he has the knowledge >to do anything more than a power test which, again, would not be very useful >and could even be detrimental. Exactly. The machine has a 3-phase 208/240V plug, they don't have such an outlet. Their efforts stop right there. But you're all focussed on that, and missing another important detail. The machine has a liquid cooling system. Some of the hoses look like they are Tygon, in the age-decayed brittle stage. Touch them and they crumble away. Running the machine without cooling would utterly wreck it. Even if they solved the mains power problem, they would be very unwise to actually power it up. The 'installation and configuration' manual for this machine would be huge. They don't have it. Plus, it's a mainframe. Not even any blinkenlights. Without setting it up as a complete system with everything interconnected properly, how would you even know it was running correctly? Plus you can safely assume at least some of the system unit interconnect cables are missing. Potentially weeks, even months of restoration work for a buyer, before even daring to apply power. Then if there's anything wrong in the electronics, good luck diagnosing and getting spare parts. Considering the uncertainties plus high transport, restoration, operating and manhour costs, who'd buy it? A museum perhaps? Or someone wanting a 'static display object' never intending to run it. Guy
Re: VAX 780 on eBay
TU77: https://www.ebay.com/itm/275083502085 (The 11/780 is visible in That looks complete with the TM03 formatter. RM05: https://www.ebay.com/itm/284587865252 That looks like it's missing the MassBus adapter. I think two RM05's shared a cabinet between them that contained the MBA logic. Not sure if a RM03's MBA will work, quite possible (I have an RM80 that is on top of a RM03 controller MBA) CZ
Re: VAX 780 on eBay
> Way more because of inertia. Not quite a UPS, but short power glitches enough > to blink the computer room lights are not going to be seen by the mainframe. Indeed, one can purchase flywheel systems to ride through genset startup time on inertia! Thanks, Jonathan
Re: VAX 780 on eBay
On 2022-01-01 12:36 p.m., Jon Elson via cctalk wrote: On 1/1/22 1:11 PM, Bill Gunshannon via cctalk wrote: Just out of curiosity, how much current is needed for an 11/780? Depending on options, the CPU cabinet would draw about 10-12 A per line, 3-Phase 208 V. And, that is on the upper end of the range. Starting surge would be a lot more, of course. Jon How much power is used for memory and hard drives? Ben.
Re: VAX 780 on eBay
On 1/1/22 1:56 PM, W2HX via cctalk wrote: The other benefit to 3phase power to something like a computer is that the filter caps required can be much smaller. Once you rectify three phases 60* you get MUCH less ripple because every 60 degrees you have a new peak arriving. When you have a real gas (electron) guzzler like one of these, DC filtering becomes an issue. But, they DIDN'T! All power supplies on the /780 were single phase. On the IBM 370/145, they used a motor/generator set to convert 208/3 phase 60 Hz power to 415 Hz 3-phase 120 V regulated power, then fed that to 3-phase transformer/rectifiers, and finally to low-drop regulators. They also used "electronic capacitors", which was a scheme to pull extra current through the smoothing inductor during the voltage peaks, to even out the ripple. The 370/145 had 2 power supplies, one for +1.25 V 390A and the other for -3 V 390A. Jon
Re: VAX 780 on eBay
On 1/1/22 1:50 PM, W2HX via cctalk wrote: True. But if you're trying to get > $5000 for something, it doesn't seem unreasonable to suggest that investing a bit in getting an extension cord run to the location of the machine would be a good idea. The absence of that effort makes me wonder if the owner knows what the outcome of such a test would be and doesn't want to have to report it. But what would that accomplish? I think testing something like this requires a lot more effort than plugging it in and hitting the circuit breaker. To test this to see if some ODT comes up probably requires quite a lot of effort (locate a terminal/pc, wire it up, figure out where to plug it into the 780, etc. If this guy is a bulk dealer I would be surprised if he has the knowledge to do anything more than a power test which, again, would not be very useful and could even be detrimental. The /780 needs a readable "console floppy" and working drive. It loads microcode from the floppy and runs some power-on self-tests before even starting the VAX CPU. Not real likely the floppy is going to be in good condition or the drive, either. Also, the cooling blowers below the circuit boards are likely to be seized and need new bearings. Not to mention the cap banks in the power supplies at least need to be re-formed. Likely, this machine has not been turned on since 1990 or so, (just guessing). Jon
Re: VAX 780 on eBay
> On Jan 1, 2022, at 3:08 PM, Grant Taylor via cctalk > wrote: > > On 1/1/22 12:44 PM, Paul Koning via cctalk wrote: >> ... >> And of course 400 Hz gave them an additional advantage in reduced >> transformer size and reduced ripple (for a given filter capacitor). > > I was going to ask how the frequency altered the size of the ripple, but "for > a given filter capacitor" makes sense. You are messing with the ratio and > having a fixed value "for a given filter capacitor". -- If I'm even > remotely understanding correctly. The impedance of a capacitor is inversely proportional to the frequency. Given a desired ripple for a given load, you get the needed capacitor impedance, so if you increase the freqency you'd end up with smaller capacitors. You see this, big time, in modern switching supplies, where the frequency may into the many kHz or sometimes even a MHz or so, resulting in tiny filter capacitors. >> They'd do this even in devices that don't draw large amounts of power, for >> example the DD60 console display gets its power (other than fans which are >> single phase mains power) from the 400 Hz 3-phase supply feeding the >> mainframe. I'd be surprised if it uses even a kW, so this was probably a >> case of "why not since it's there to be used". > > My understanding is that some of the special power requirements had more to > do with isolation and cleanliness / quality of the power. Meaning don't try > to power the equipment off of the same circuit(s) that motors and the likes > are on which will induce lots of noise on the line, some of which might make > it into the computer and adversely effect things. True. And I forgot about the fact that you'd want to run devices interconnected by logic level signals (which is the case here) from a common power source. A lot of CDC peripherals are transformer coupled (the coax signals used in I/O channels are built that way) but the DD60 connections are DC-coupled. > The motor / generator provides a quite strong isolation for things like that. > Probably more so than just a normal transformer. Way more because of inertia. Not quite a UPS, but short power glitches enough to blink the computer room lights are not going to be seen by the mainframe. paul
Re: VAX 780 on eBay
On Sat, Jan 1, 2022 at 11:55 AM W2HX via cctalk wrote: > > > True. But if you're trying to get > $5000 for something, it doesn't seem > unreasonable to suggest that investing a bit in getting an extension cord > run to the location of the machine would be a good idea. The absence of > that effort makes me wonder if the owner knows what the outcome of such a > test would be and doesn't want to have to report it. > > > > But what would that accomplish? I think testing something like this > requires a lot more effort than plugging it in and hitting the circuit > breaker. To test this to see if some ODT comes up probably requires quite a > lot of effort (locate a terminal/pc, wire it up, figure out where to plug > it into the 780, etc. If this guy is a bulk dealer I would be surprised if > he has the knowledge to do anything more than a power test which, again, > would not be very useful and could even be detrimental. > Right. I'll pay significantly less for an 11/780 that some random scrapper has powered up. - Josh > > > 73 Eugene W2HX > Subscribe to my Youtube Channel: > https://www.youtube.com/c/w2hx-channel/videos > > > >
Re: VAX 780 on eBay
It splits the input 3 phase 120/208 30A input to separate 120V circuits. 3*30A 120V circuits if you want. Mine used about 3KVA, so it'll actually (just barely) run off of a single 30A/120V or multiple 15/20A 120V circuits if you rewire the input a bit. Patrick Finnegan On Sat, Jan 1, 2022, 14:11 Bill Gunshannon via cctalk wrote: > On 1/1/22 1:53 PM, Grant Taylor via cctalk wrote: > > On 1/1/22 11:46 AM, Bill Gunshannon via cctalk wrote: > >> Having 240 in your house does not necessarily mean you have 240 > >> outlets anywhere and not everyone is capable of doing their own house > >> wiring. > > > > There may even be 240 V outlets but not available when / where needed. > > E.g. in use (stove, dryer, water heater) or too far away to be able to > > plug the VAX in for testing. Then there's also the chance that the > > plugs don't match. > > > > I do 120 V wiring semi-regular. I've done 240 V wiring before. I'm > > sure that I'll do it again. But I'm always afraid that failure mode on > > the 240 V is going to fail spectacularly. My only saving grace is that > > the breaker will almost certainly trip in short order to mitigate my > > failure. Thankfully no breaker trips thusfar. > > In my current house I have done 240V/50A wiring, 240V/50A Sub Panel, > lots of 240V/30A outlets. None of which I would advise the usual > amateur to do. :-) > > Just out of curiosity, how much current is needed for an 11/780? > > bill > > >
Re: VAX 780 on eBay
On 1/1/22 12:59 PM, Jonathan Chapman via cctalk wrote: They're 180 degrees out. Sufficiently different for a number of applications, but certainly not all! They are 180° out of phase with respect to each other. But they are the same single phase when viewed by anything outside of them. -- Grant. . . . unix || die
Re: VAX 780 on eBay
On 1/1/22 12:44 PM, Paul Koning via cctalk wrote: Could be. For the CDC case, I see actual 3-phase DC supplies, i.e., 3 phase bridge rectifiers fed by 3-phase transformers. Interesting. That brings to mind 6ɸ DC supplies. -- Two typical 3ɸ rectifier networks (making DC pulses be 60° apart) separated by a ∆ / Y or Y / ∆ transformer inducing a 30° phase shift between them. Thereby causing a net effect of 12 x DC pulses 30° apart. If you run those off one phase the ripple would be a lot larger. Indeed. And of course 400 Hz gave them an additional advantage in reduced transformer size and reduced ripple (for a given filter capacitor). I was going to ask how the frequency altered the size of the ripple, but "for a given filter capacitor" makes sense. You are messing with the ratio and having a fixed value "for a given filter capacitor". -- If I'm even remotely understanding correctly. They'd do this even in devices that don't draw large amounts of power, for example the DD60 console display gets its power (other than fans which are single phase mains power) from the 400 Hz 3-phase supply feeding the mainframe. I'd be surprised if it uses even a kW, so this was probably a case of "why not since it's there to be used". My understanding is that some of the special power requirements had more to do with isolation and cleanliness / quality of the power. Meaning don't try to power the equipment off of the same circuit(s) that motors and the likes are on which will induce lots of noise on the line, some of which might make it into the computer and adversely effect things. The motor / generator provides a quite strong isolation for things like that. Probably more so than just a normal transformer. The frequency change means that a simple isolation transformer won't suffice. The higher frequency also has benefits of reducing the size of other down stream components. I find this to be interesting to learn, even if I'll almost certainly never actually work near anything that uses it. -- Grant. . . . unix || die
Re: VAX 780 on eBay
> I have questions > > Where are you getting two /different/ phases? -- Remember, the > different legs on residential 120/240 wiring are really the same single > phase. They're 180 degrees out. Sufficiently different for a number of applications, but certainly not all! Thanks, Jonathan
RE: VAX 780 on eBay
The other benefit to 3phase power to something like a computer is that the filter caps required can be much smaller. Once you rectify three phases 60* you get MUCH less ripple because every 60 degrees you have a new peak arriving. When you have a real gas (electron) guzzler like one of these, DC filtering becomes an issue. 73 Eugene W2HX Subscribe to my Youtube Channel: https://www.youtube.com/c/w2hx-channel/videos -Original Message- From: cctalk On Behalf Of Jonathan Chapman via cctalk Sent: Saturday, January 1, 2022 2:35 PM To: Grant Taylor ; General Discussion: On-Topic and Off-Topic Posts Subject: Re: VAX 780 on eBay > I think that's the same with all the /computer/ equipment that I've > seen which connects to 3ɸ power. A single phase could be used for all of it. Computer exist which require three phase at a unit power supply level. It's often also used for large blowers if the cabinet(s) don't strictly require airflow from e.g. a raised floor. > But I'm told that it's simpler / more economical (from a wiring / > cable plant point of view) to deliver more power to the equipment as > 3ɸ than it is 1ɸ. It also saves you on current-carrying conductors for raceway fill calculations as long as your power factor isn't too bad. Thanks, Jonathan
Re: VAX 780 on eBay
On 1/1/22 12:43 PM, Dennis Boone via cctalk wrote: My Multiprise 2003/205 claims to want a pair of 3-phase inputs. Is it assumed that those 2 x 3ɸ inputs are feed from different paths, thus path redundancy? I'd think that the phases would be the same. I've run it on two "phases" on a single side. I have questions Where are you getting two /different/ phases? -- Remember, the different legs on residential 120/240 wiring are really the same single phase. How do you get *two* /different/ phases without access to a *third* phase? There are only a few places in the U.S.A. (and I'm not aware of anywhere else in the world) that actually have 2ɸ power (where the ɸ are 90° out of phase with each other). What is a phase vs what is a line comes into context here. It bitches, of course, I could see how wiring two legs of a 120/240 1ɸ as if it were 2 phases of a 3ɸ supply would make something mad. and one loses the intended redundancy, but it runs. Indeed. But if one is doing this, chances are fairly good that one is most interested in the fact that /it/ /runs/ and cares much less about /redundancy/. ;-) -- Grant. . . . unix || die
RE: VAX 780 on eBay
> True. But if you're trying to get > $5000 for something, it doesn't seem unreasonable to suggest that investing a bit in getting an extension cord run to the location of the machine would be a good idea. The absence of that effort makes me wonder if the owner knows what the outcome of such a test would be and doesn't want to have to report it. > But what would that accomplish? I think testing something like this requires a lot more effort than plugging it in and hitting the circuit breaker. To test this to see if some ODT comes up probably requires quite a lot of effort (locate a terminal/pc, wire it up, figure out where to plug it into the 780, etc. If this guy is a bulk dealer I would be surprised if he has the knowledge to do anything more than a power test which, again, would not be very useful and could even be detrimental. 73 Eugene W2HX Subscribe to my Youtube Channel: https://www.youtube.com/c/w2hx-channel/videos
Re: VAX 780 on eBay
> On Jan 1, 2022, at 2:38 PM, Grant Taylor via cctalk > wrote: > > On 1/1/22 12:33 PM, Paul Koning via cctalk wrote: >> And mainframes may use 3-phase power supplies; CDC 6000 mainframes do, >> though with those it's 3 phase 400 Hz produced by motor-generators (which in >> turn run off 3-phase mains power). > > I know that some IBM mainframes prefer 3ɸ power but I know of multiple people > that have re-wired their CECs to use 1ɸ power. They too are largely > independent 1ɸ supplies on different phases to jointly power a common > internal bus. So re-wiring the necessary supplies to the same phase is > mostly not a big deal. > > Apparently even IBM sold and supported some systems in this configuration. > The only down side is that it put an upper cap on the amount of power that > you could draw and thus things that you could run in this configuration. But > for smaller installations, it's perfectly fine. Could be. For the CDC case, I see actual 3-phase DC supplies, i.e., 3 phase bridge rectifiers fed by 3-phase transformers. If you run those off one phase the ripple would be a lot larger. And of course 400 Hz gave them an additional advantage in reduced transformer size and reduced ripple (for a given filter capacitor). They'd do this even in devices that don't draw large amounts of power, for example the DD60 console display gets its power (other than fans which are single phase mains power) from the 400 Hz 3-phase supply feeding the mainframe. I'd be surprised if it uses even a kW, so this was probably a case of "why not since it's there to be used". paul
Re: VAX 780 on eBay
> I know that some IBM mainframes prefer 3ɸ power but I know of multiple > people that have re-wired their CECs to use 1ɸ power. My Multiprise 2003/205 claims to want a pair of 3-phase inputs. I've run it on two "phases" on a single side. It bitches, of course, and one loses the intended redundancy, but it runs. De
Re: VAX 780 on eBay
On 1/1/22 12:33 PM, Paul Koning via cctalk wrote: And mainframes may use 3-phase power supplies; CDC 6000 mainframes do, though with those it's 3 phase 400 Hz produced by motor-generators (which in turn run off 3-phase mains power). I know that some IBM mainframes prefer 3ɸ power but I know of multiple people that have re-wired their CECs to use 1ɸ power. They too are largely independent 1ɸ supplies on different phases to jointly power a common internal bus. So re-wiring the necessary supplies to the same phase is mostly not a big deal. Apparently even IBM sold and supported some systems in this configuration. The only down side is that it put an upper cap on the amount of power that you could draw and thus things that you could run in this configuration. But for smaller installations, it's perfectly fine. -- Grant. . . . unix || die
Re: VAX 780 on eBay
Sorta nitpick, but: > 3-phase 208/240 V WYE power Not a thing. It's 120/208Y or 240 delta, high leg or not. Nameplates suggest 120/208Y which is the most common "not a machine shop" configuration. Thanks, Jonathan
Re: VAX 780 on eBay
On 1/1/22 1:11 PM, Bill Gunshannon via cctalk wrote: Just out of curiosity, how much current is needed for an 11/780? Depending on options, the CPU cabinet would draw about 10-12 A per line, 3-Phase 208 V. And, that is on the upper end of the range. Starting surge would be a lot more, of course. Jon
Re: VAX 780 on eBay
> I think that's the same with all the /computer/ equipment that I've seen > which connects to 3ɸ power. A single phase could be used for all of it. Computer exist which require three phase at a unit power supply level. It's often also used for large blowers if the cabinet(s) don't strictly require airflow from e.g. a raised floor. > But I'm told that it's simpler / more economical (from a wiring / > cable plant point of view) to deliver more power to the equipment as 3ɸ > than it is 1ɸ. It also saves you on current-carrying conductors for raceway fill calculations as long as your power factor isn't too bad. Thanks, Jonathan
Re: VAX 780 on eBay
> On Jan 1, 2022, at 2:21 PM, Grant Taylor via cctalk > wrote: > > On 1/1/22 12:17 PM, Dennis Boone via cctalk wrote: >> IIRC nothing in the VAX cpu actually requires 3 phase. The PDU(s) just eat >> that from the wall. > > I think that's the same with all the /computer/ equipment that I've seen > which connects to 3ɸ power. A single phase could be used for all of it. But > I'm told that it's simpler / more economical (from a wiring / cable plant > point of view) to deliver more power to the equipment as 3ɸ than it is 1ɸ. Largely true, but some disk drives (RP06? RP04?) use 3-phase spindle motors. And mainframes may use 3-phase power supplies; CDC 6000 mainframes do, though with those it's 3 phase 400 Hz produced by motor-generators (which in turn run off 3-phase mains power). paul
Re: VAX 780 on eBay
On 1/1/2022 1:10 PM, Jon Elson via cctalk wrote: On 1/1/22 12:12 PM, Noel Chiappa via cctalk wrote: This: https://www.ebay.com/itm/275084268137 The starting price is expensive, but probably not utterly unreasonable, given that: They don't have a front picture, but there is a rear picture of a TU-77/TU-78 tape drive interior. As for testing, the 780 came wired for 208/240 3 phase power, with a big 5-pin plug. The CPU cabinet seems to have 2 Massbus controllers, I think. So, maybe there's a Massbus disk included. Jon In separate auctions they have a RM05 and a TU77 TU77: https://www.ebay.com/itm/275083502085 (The 11/780 is visible in the background of the first picture) RM05: https://www.ebay.com/itm/284587865252 -- John H. Reinhardt
Re: VAX 780 on eBay
On 1/1/22 12:17 PM, Dennis Boone via cctalk wrote: IIRC nothing in the VAX cpu actually requires 3 phase. The PDU(s) just eat that from the wall. I think that's the same with all the /computer/ equipment that I've seen which connects to 3ɸ power. A single phase could be used for all of it. But I'm told that it's simpler / more economical (from a wiring / cable plant point of view) to deliver more power to the equipment as 3ɸ than it is 1ɸ. -- Grant. . . . unix || die
Re: VAX 780 on eBay
On 1/1/22 12:51 PM, Paul Koning via cctalk wrote: True. But if you're trying to get > $5000 for something, it doesn't seem unreasonable to suggest that investing a bit in getting an extension cord run to the location of the machine would be a good idea. The absence of that effort makes me wonder if the owner knows what the outcome of such a test would be and doesn't want to have to report it. The /780 came standard with a 5-pin Hubbell twist-lock connector for 3-phase 208/240 V WYE power. While it could be rewired for single-phase power, it would take fairly massive rewiring of the power control. The 3 blowers all ran off line-line power, I think, and the H7100 power supplies ran off 120V line-neutral from different phases. Jon
Re: VAX 780 on eBay
> In my current house I have done 240V/50A wiring, 240V/50A Sub Panel, > lots of 240V/30A outlets. None of which I would advise the usual > amateur to do. :-) IIRC nothing in the VAX cpu actually requires 3 phase. The PDU(s) just eat that from the wall. De
Re: VAX 780 on eBay
On 1/1/22 1:53 PM, Grant Taylor via cctalk wrote: On 1/1/22 11:46 AM, Bill Gunshannon via cctalk wrote: Having 240 in your house does not necessarily mean you have 240 outlets anywhere and not everyone is capable of doing their own house wiring. There may even be 240 V outlets but not available when / where needed. E.g. in use (stove, dryer, water heater) or too far away to be able to plug the VAX in for testing. Then there's also the chance that the plugs don't match. I do 120 V wiring semi-regular. I've done 240 V wiring before. I'm sure that I'll do it again. But I'm always afraid that failure mode on the 240 V is going to fail spectacularly. My only saving grace is that the breaker will almost certainly trip in short order to mitigate my failure. Thankfully no breaker trips thusfar. In my current house I have done 240V/50A wiring, 240V/50A Sub Panel, lots of 240V/30A outlets. None of which I would advise the usual amateur to do. :-) Just out of curiosity, how much current is needed for an 11/780? bill
Re: VAX 780 on eBay
On 1/1/22 12:12 PM, Noel Chiappa via cctalk wrote: This: https://www.ebay.com/itm/275084268137 The starting price is expensive, but probably not utterly unreasonable, given that: They don't have a front picture, but there is a rear picture of a TU-77/TU-78 tape drive interior. As for testing, the 780 came wired for 208/240 3 phase power, with a big 5-pin plug. The CPU cabinet seems to have 2 Massbus controllers, I think. So, maybe there's a Massbus disk included. Jon
Re: VAX 780 on eBay
On 1/1/22 11:49 AM, John H. Reinhardt via cctalk wrote: TU77: https://www.ebay.com/itm/275083502085 (The 11/780 is visible in the background of the first picture) The TU77 has a 3ɸ power plug on it. That probably explains why testing it would be problematic in a residential settings. 1ɸ240V is vastly different than 3ɸ120/208V. The picture after the plug also looks remarkably like the back plane of the VAX. -- Grant. . . . unix || die
Re: VAX 780 on eBay
On 1/1/22 11:49 AM, Jonathan Chapman via cctalk wrote: Indeed, Tuscon Buying Group deals in a lot of industrial stuff -- we buy from them at $day_job sometimes. I'd be really surprised if they don't have 240V available for testing somewhere in their shop. There's a difference in having something /in/ /shop/ vs the shop selling it for someone when it's located elsewhere. Where we see it, the background indicates that the VAX is located in a residential neighborhood. Or at least was when the pictures were taken. -- Grant. . . . unix || die
Re: VAX 780 on eBay
On 1/1/22 11:51 AM, Paul Koning via cctalk wrote: True. But if you're trying to get > $5000 for something, it doesn't seem unreasonable to suggest that investing a bit in getting an extension cord run to the location of the machine would be a good idea. The absence of that effort makes me wonder if the owner knows what the outcome of such a test would be and doesn't want to have to report it. Maybe. But how many "one more step" tests can the seller do vs being honest and up front. Maybe the seller had heard about power supplies (caps) failing spectacularly ~> catastrophically and doesn't know how nor want to do the work to test. What's after the "smoke test"? Or, just call it where it is. ;-) -- Grant. . . . unix || die
Re: VAX 780 on eBay
On 1/1/22 11:46 AM, Bill Gunshannon via cctalk wrote: Having 240 in your house does not necessarily mean you have 240 outlets anywhere and not everyone is capable of doing their own house wiring. There may even be 240 V outlets but not available when / where needed. E.g. in use (stove, dryer, water heater) or too far away to be able to plug the VAX in for testing. Then there's also the chance that the plugs don't match. I do 120 V wiring semi-regular. I've done 240 V wiring before. I'm sure that I'll do it again. But I'm always afraid that failure mode on the 240 V is going to fail spectacularly. My only saving grace is that the breaker will almost certainly trip in short order to mitigate my failure. Thankfully no breaker trips thusfar. -- Grant. . . . unix || die
Re: VAX 780 on eBay
> On Jan 1, 2022, at 1:46 PM, Bill Gunshannon via cctalk > wrote: > > On 1/1/22 1:40 PM, Paul Koning via cctalk wrote: >>> On Jan 1, 2022, at 1:12 PM, Noel Chiappa via cctalk >>> wrote: >>> >>> This: >>> >>>https://www.ebay.com/itm/275084268137 >>> >>> The starting price is expensive, but probably not utterly unreasonable, >>> given that: >>> >>> - the 780 was the first VAX, and thus historically important >>> >>> - 780's are incredibly rare; this is the first one I recall seeing for sale >>> in the classic computer era (versus several -11/70's, /40s, etc) >>> >>> - this one appears to be reasonably complete; no idea if all the key CPU >>> boards are included, but it's things like the backplane, etc (all of which >>> seem to be there) which would be completely impossible to find now - if any >>> boards _are_ missing, there's at least the _hope_ that they can be located >>> (780 boards seem to come by every so often on eBait), since people seem to >>> keep boards, not realizing that without the other bits they are useless >> Interesting, but the argument for why it's not tested is implausible which >> makes me very suspicious. I suppose there might be a few American homes >> that have only 110 volt power, but I'm hard pressed to think of any I have >> ever seen, and that includes really old houses. > > Having 240 in your house does not necessarily mean you have > 240 outlets anywhere and not everyone is capable of doing > their own house wiring. True. But if you're trying to get > $5000 for something, it doesn't seem unreasonable to suggest that investing a bit in getting an extension cord run to the location of the machine would be a good idea. The absence of that effort makes me wonder if the owner knows what the outcome of such a test would be and doesn't want to have to report it. paul
Re: VAX 780 on eBay
On 1/1/2022 12:40 PM, Paul Koning via cctalk wrote: On Jan 1, 2022, at 1:12 PM, Noel Chiappa via cctalk wrote: This: https://www.ebay.com/itm/275084268137 The starting price is expensive, but probably not utterly unreasonable, given that: - the 780 was the first VAX, and thus historically important - 780's are incredibly rare; this is the first one I recall seeing for sale in the classic computer era (versus several -11/70's, /40s, etc) - this one appears to be reasonably complete; no idea if all the key CPU boards are included, but it's things like the backplane, etc (all of which seem to be there) which would be completely impossible to find now - if any boards _are_ missing, there's at least the _hope_ that they can be located (780 boards seem to come by every so often on eBait), since people seem to keep boards, not realizing that without the other bits they are useless Interesting, but the argument for why it's not tested is implausible which makes me very suspicious. I suppose there might be a few American homes that have only 110 volt power, but I'm hard pressed to think of any I have ever seen, and that includes really old houses. paul Possibly part of the same installation they have: TU77: https://www.ebay.com/itm/275083502085 (The 11/780 is visible in the background of the first picture) RM05: https://www.ebay.com/itm/284587865252 LA120: https://www.ebay.com/itm/275084461044 Prices seem on the high end but not totally unreasonable. There don't seem to be any RM05 packs included with the drive. -- John H. Reinhardt
Re: VAX 780 on eBay
> this is the first one I recall seeing for sale > in the classic computer era (versus several -11/70's, /40s, etc) Last one that went auction-style on eBay went for $1,178.00, local pick-up. I know the buyer. I still wouldn't think $5K is totally unreasonable, given the clean condition and that they're willing to freight it out. > Interesting, but the argument for why it's not tested is implausible which > makes me very suspicious. Indeed, Tuscon Buying Group deals in a lot of industrial stuff -- we buy from them at $day_job sometimes. I'd be really surprised if they don't have 240V available for testing somewhere in their shop. Thanks, Jonathan
Re: VAX 780 on eBay
On 1/1/22 1:40 PM, Paul Koning via cctalk wrote: On Jan 1, 2022, at 1:12 PM, Noel Chiappa via cctalk wrote: This: https://www.ebay.com/itm/275084268137 The starting price is expensive, but probably not utterly unreasonable, given that: - the 780 was the first VAX, and thus historically important - 780's are incredibly rare; this is the first one I recall seeing for sale in the classic computer era (versus several -11/70's, /40s, etc) - this one appears to be reasonably complete; no idea if all the key CPU boards are included, but it's things like the backplane, etc (all of which seem to be there) which would be completely impossible to find now - if any boards _are_ missing, there's at least the _hope_ that they can be located (780 boards seem to come by every so often on eBait), since people seem to keep boards, not realizing that without the other bits they are useless Interesting, but the argument for why it's not tested is implausible which makes me very suspicious. I suppose there might be a few American homes that have only 110 volt power, but I'm hard pressed to think of any I have ever seen, and that includes really old houses. Having 240 in your house does not necessarily mean you have 240 outlets anywhere and not everyone is capable of doing their own house wiring. bill
Re: VAX 780 on eBay
> On Jan 1, 2022, at 1:12 PM, Noel Chiappa via cctalk > wrote: > > This: > >https://www.ebay.com/itm/275084268137 > > The starting price is expensive, but probably not utterly unreasonable, > given that: > > - the 780 was the first VAX, and thus historically important > > - 780's are incredibly rare; this is the first one I recall seeing for sale > in the classic computer era (versus several -11/70's, /40s, etc) > > - this one appears to be reasonably complete; no idea if all the key CPU > boards are included, but it's things like the backplane, etc (all of which > seem to be there) which would be completely impossible to find now - if any > boards _are_ missing, there's at least the _hope_ that they can be located > (780 boards seem to come by every so often on eBait), since people seem to > keep boards, not realizing that without the other bits they are useless Interesting, but the argument for why it's not tested is implausible which makes me very suspicious. I suppose there might be a few American homes that have only 110 volt power, but I'm hard pressed to think of any I have ever seen, and that includes really old houses. paul
VAX 780 on eBay
This: https://www.ebay.com/itm/275084268137 The starting price is expensive, but probably not utterly unreasonable, given that: - the 780 was the first VAX, and thus historically important - 780's are incredibly rare; this is the first one I recall seeing for sale in the classic computer era (versus several -11/70's, /40s, etc) - this one appears to be reasonably complete; no idea if all the key CPU boards are included, but it's things like the backplane, etc (all of which seem to be there) which would be completely impossible to find now - if any boards _are_ missing, there's at least the _hope_ that they can be located (780 boards seem to come by every so often on eBait), since people seem to keep boards, not realizing that without the other bits they are useless Anyway I fully expect it to go (because of those, especially i and ii) for a _lot_ more than the opening price. I've sent the seller info on the complete 780 board set, and a suggestion that it's in their own best interest (maximize bidding) to check to see if it's complete. Noel
