Image Map Image Map
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 30

Thread: VAX 11/785 System haul

  1. #11
    Join Date
    Jul 2014
    Location
    Germany, near Göttingen
    Posts
    25

    Default

    Here in Germany three-phase power is standard in every house.

    Like the distribution photo in Chuck(G)s post - but bigger.
    And out of it normally 240V, if you have some bigger machines or an kitchen stove you will need three-phase 400V.

    But, the VAX will only use 12A per phase, an normal kitchen stove here does need usually the full 16A.
    With that kind of three-phase you are able to test some bigger Alphas, too.
    For example the older turbolaser and newer wildfire or marvel systems ( 8400 / GS140 / GS160 / GS1280 ).
    [You now know also where my user name comes from / is an alias for. My first contact to big Alphas was circa in y2k with the first GS160 system delivered to europe ! ]

    Like the VAX, on those systems internally the PDUs do split the power and the power supplies use only 240V.

    There are systems who use the 400V for the power supplies, but afaik none of the DEC systems - not PDPs, nor VAX, nor Alpha.

    On none of my bigger DEC systems the 400V is used, always after the PDU 240V goes out.

  2. #12
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    27,866
    Blog Entries
    20

    Default

    I've been envious of you folks in Deutschland for doing things right. Although my (rural) neighborhood is supplied by a 3-phase 12KV line, individual distribution is single-phase only. I suppose if you are a heavy use customer you can talk the utility into providing 3-phase, but only 2 wires are buried alongside my driveway carrying only one phase of the 12KV to the transformer in my yard. Friends with larger machine tools in their home shops have to resort to phase converters to get the power they need.

    It's really silly--every few years, the utility comes around to the distribution box on the street and switches the phase that your power distribution is connected to in the name of "phase balancing". Even my home's heat pump compressor is single-phase, even though it's on a 50A breaker. Three-phase AC motors are more efficient and don't have the extra burden of start/run circuitry (single-phase large motors have two capacitors--a "start" and a "run" which have to be replaced every decade or so).

    I suspect your world would be complete if you had 400Hz 3-phase power for those old mainframes.

  3. #13
    Join Date
    May 2011
    Location
    Liverpool, England
    Posts
    325

    Default

    ""For example the older turbolaser and newer wildfire or marvel systems ( 8400 / GS140 / GS160 / GS1280 ).
    [You now know also where my user name comes from / is an alias for. My first contact to big Alphas was circa in y2k with the first GS160 system delivered to europe ! ]""

    One of my customers is still using two GS160's running Tru64. They were delivered a around 2000 also. Had to replace a few H-switch clock modules and a backplane in the last year, but they are still ticking over. I'd like one of these when they become redundant but the three-phase and size will be an issue.

  4. #14

    Default

    Quote Originally Posted by Chuck(G) View Post
    I've been envious of you folks in Deutschland for doing things right. Although my (rural) neighborhood is supplied by a 3-phase 12KV line, individual distribution is single-phase only. I suppose if you are a heavy use customer you can talk the utility into providing 3-phase, but only 2 wires are buried alongside my driveway carrying only one phase of the 12KV to the transformer in my yard.
    There is 3-phase power on the street about 150 feet from my house. The power company wanted more than $10,000 to run the wires to my house.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  5. #15

    Default

    Quote Originally Posted by Chuck(G) View Post
    I've been envious of you folks in Deutschland for doing things right. Although my (rural) neighborhood is supplied by a 3-phase 12KV line, individual distribution is single-phase only. I suppose if you are a heavy use customer you can talk the utility into providing 3-phase, but only 2 wires are buried alongside my driveway carrying only one phase of the 12KV to the transformer in my yard. Friends with larger machine tools in their home shops have to resort to phase converters to get the power they need.
    Most houses in Sweden also have three phase. I am pretty convinced that most of northern Europe has this as well. I have 25A per phase, three phase, into my house.

  6. #16

    Default

    Quote Originally Posted by Wildfire View Post
    Yes, three phase power is available where the system is stored at the moment and also some work will be done on it there.
    It is good that the 6 RA drives came with the system. A member of my computer club and i have some experience with repairing RA60 and also R80/RA81/RA82.

    Uhmm, last year there has been another big haul with an 11/730 System from an physicist who passed away - and there have been R80/RA60/RA81/RA82 drives - 6 in total.
    2 RA60 and one RA81 have been repaired and are up and running now.

    But i would love to get also some Massbus drives, i do not know if i am able to get them up and running if i had them - but as an collector you want these also to complete the different types of drives DEC sold.
    We have quite a few RA80 and RA81 drives in the RICM collection. All of them spin up for a few seconds and then shut off. They indicate a problem with the spindle speed sensor. I have seen some reports of people repairing the spindle sensor by installing a new LED and photodiode.

    I have an RP06 and an RM03 at home. I was able to get the suitcase containing the test electronics needed for head alignment and testing for both drives. I also have the mechanical tools for the RP06 to replace heads and the spindle bearings.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  7. #17
    Join Date
    Jan 2010
    Location
    Central VA
    Posts
    4,042

    Default

    On top of the high installation costs, US power companies often want to charge you as a commercial customer with demand pricing for three phase. If you're an infrequent three phase user, it's often cheaper to get a used genset. I've got two that provide three phase: 7.5 kW 208 VAC wye, and a 25 kW 12-lead reconnectable.

    Good to hear that the Euro spec machines break out power into single-phase as well -- figured this would be the case.

  8. Default

    Quote Originally Posted by Wildfire View Post
    A few weeks ago one of my collectors dreams came true - i was able to get an 11/785 System.
    It has been stored since the 1990s in an garage of the last owner and since then not been powered on.
    I have some comments on the TU78 and LP26 which may be helpful.

    First, the TU78 is a wonderful drive which was marred by total ineptitude on the part of DEC. To give you an idea, the drives would report bogus read errors because the TM78 controller (in the bottom of the master drive) had the wrong capacitors on the read channel preamps. There was an FCO to swap out those boards for ones with the correct capacitors. Unfortunately, the boards sent to the field for that FCO had the correct capacitors, but installed backwards. There were similar foibles in the auto-load system. I got pretty good at repairing these (and the similar TU77). Drives I worked on would run the exerciser diagnostic for 8+ hours without logging even a single soft error. People would bring me drives from several hundred miles away for me to repair, in exchange for trading for various parts. I was rather surprised when a rental truck showed up and my DEC Field Service guy dropped off some drives for repair.

    I ended up running 2 TU77 and 5 TU78 drives at SPC, all masters. The TU77s were because the RSTS/E didn't support TU78 drives.

    Trivia: The reason that the TU78/TA78 were replaced with the TU79/TA79 was because DEC wasn't buying enough drives to have the manufacturer continue to produce them with that door. If you look closely at a TU79/TA79, you'll see 3 small rectangles close to each other on the door. Those are for the IBM channel and unit number (normally something like 280 on a low-end IBM) stickers, because they were selling most of those transports as plug-compatible drives for IBM systems.

    The LP25/LP26 are nice printers - I like them much better than the Dataproducts B300/B600 that they're based on. They have a very nice flat top which is handy for reviewing printouts, while the B300/B600 have a clamshell top that nothing will stay on. The only problem with the DEC-style top is that the two gas struts that hold the lid up tend to let go at the slightest provocation, causing the cover to slam down on your head when you're changing the paper. The main failure mode of these units is the ribbon feed rollers for the "ribbon stuffer" that folds the ribbon back into the cassette, and (on older units) the large rubber hubs that drive the band (one has a motor under it, the other one is just an idler). There was a manufacturing change (not sure if it ever came out as a FCO) to replace the orginal style metal hubs that had rubber inserts where the band ran, to a version that was entirely rubberized with a different material. The most common cause for these two items to fail is aftermarket ribbons that use a different solvent for the ink, which attacks the plastic. Unfortunately, these parts are almost certainly no longer available and any spares have probably turned to gunk over time. On both the DEC and Dataproducts versions, the double-sided tape that holds the lid gasket to the printer has probably let go, but that should be easy to replace with any modern equivalent. If I'm remembering right, the DEC printers used a "refrigerator door" type gasket while the Dataproducts ones used a plasticized welting.

    It is trivial to drive these printers with a Centronics-style interface instead of the Dataproducts interface. Dataproducts made an optional interface card, but all you needed was a 14-pin 7400 series IC to invert a couple of the signals. I made cables that had a "rat in a snake" bulge in the middle where I placed the IC and then put heat-shrink around it. I used those with DCA IRMAprint controllers to emulate IBM 3287 printers.

    I do have a full set of service documentation here for them - the "B-Series Master Support and Logistics Manual, Volume I and II - 267726A", and the "B-series History File" which is something like 700 pages of customer information bulletins and field change orders. The only thing I can't find offhand are the firmware listings. Al, if you want to grab these for Bitsavers, just drop me a note and tell me where to ship them.

  9. #19

    Default

    I have fond memories of operating a TU77 on a VAX-11/78x when I worked part-time as a computer operator at UCI around 1990. I liked that noisy beast.

    Were the LP32 printers any good? I want one because that "LP32" plug on the back of my VAX-11/730 with nothing plugged into it makes me twitchy.

  10. Default

    Quote Originally Posted by NF6X View Post
    I have fond memories of operating a TU77 on a VAX-11/78x when I worked part-time as a computer operator at UCI around 1990. I liked that noisy beast.
    Those drives were quite something when used with VMSTPC and short record sizes.

    Were the LP32 printers any good? I want one because that "LP32" plug on the back of my VAX-11/730 with nothing plugged into it makes me twitchy.
    I think that's just a generic term for the output half of the parallel port on a DMF32 card. The DMF32 was a single-slot hodgepodge of something sort of like a DZ-11, somthing mostly like a DR-11, and a sync port that was its own kettle of fish, all rolled up behind an AM2901. You might say it was everything including the kitchen sync.

    The board was bizarre enough that none of the PDP-11 operating systems supported it. I think 4BSD ignored the sync hardware and the parallel input port.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •