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Thread: VAX 11/785 System haul

  1. #21
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    Quote Originally Posted by NF6X View Post
    Yes, that's exactly how it works! And I have been at both ends of those "here's a really cool thing for free" transactions.



    I would offer to trade a 5-ton truck for a VAX, but the shipping would be crazy! But I can't complain. I have a nice 11/730 system already, and I don't have room for a bigger VAX at this time, anyway. That's why I'm only a little bit jealous.

    Congratulations on your new VAX!
    Thank you

    Would you also agree to the following / or had the same experience: ?

    When you want to have a special system you can have luck and find or get one fast,
    the normal way is that it takes time to find one.
    BUT - if you managed to get one suddenly an other one or multiples pop up out of the fog...


    Is there an truck drivers license needed in the US to drive your 5-ton truck ?
    Here in Germany with my drivers license i did make i can drive cars with up to 3,5 tons and trucks up to 7,5 tons.
    But i think about 10-15 years ago this changed for the younger generation, you must make some extra hours in driving practice these things and eventually an more complex exam.

  2. #22
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    Quote Originally Posted by Chuck(G) View Post

    I suspect your world would be complete if you had 400Hz 3-phase power for those old mainframes.
    Hmmm, this reminds me that there is an frequency transformer unit still on my search / wishlist to get sufficient 400 Hz power for my ROLM MSE/14 systems here.
    But up to now i am happy that no 400 Hz 3-phase is needed for the systems i collected up to now.


    Here in Germany are some other computer folks who have old iron that needs 400 Hz 3-phase and they also have the motor / generator converter unit they need for it.
    If you want to take a look here:
    https://cray-cyber.org/old/index.html

  3. #23
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    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.

    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).
    Interesting how balancing and keeping up the power net is done where you live.
    Yes, three phase is more efficient.
    When you are a big business power customer here you have to take care that you do not disbalance the phases with too much difference in load and also must have an compensation unit
    that the three phases do not run out of phase to much.
    There are special counters installed for these "Blindleistung". If you have too much phasing out you will have to pay extra money because the generators of the power distribution company
    are extra stressed with this kind of load.


    Also interesting:
    PDP11s, VAXen and Alpha have been used widely in the field of power distibution and switching here in the SCADA predecessor systems.
    Until a few years ago.
    And you can earn money to keep up the power distribution nets - if you have the right machines you do not need anymore but they must be still connected.
    For example an mill motor with 1 Megawatt.
    There are times when too much power is available in the net. This means that the frequency goes up from the 50Hz.
    So there are some kind of cluster of machines who the power distributors have access to.
    So they turn them on and burn the not needed energy to keep the frequency right.

  4. #24
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    Quote Originally Posted by PG31 View Post
    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.
    Sounds interesting, if there is a chance to get one of those when they are powered off please keep me in mind and send me a note.

  5. #25
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    Quote Originally Posted by m_thompson View Post
    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.
    We did have the same problem with one drive which needed also a new LED and photodiode.
    BUT, keep in mind when you still have some data on the drive unit you want to access do not loosen or exchange the whole plastic unit with the components - you will loose the synchron tracking the drive was initiated with.

    If you have luck you only need to clean the LED and photodiode with compressed air and also Q-Tips with isoprop.

    Nice tools you did rescue for your drives - did you ever have to use them up to now ?

  6. #26
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    Quote Originally Posted by Terry Kennedy View Post
    I have some comments on the TU78 and LP26 which may be helpful.
    Thank you for your tips, i will keep them in mind when i work on the TU and LP.
    Eventually there will be further questions

  7. #27
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    Quote Originally Posted by Wildfire View Post
    Interesting how balancing and keeping up the power net is done where you live.
    Yes, three phase is more efficient.
    When you are a big business power customer here you have to take care that you do not disbalance the phases with too much difference in load and also must have an compensation unit
    that the three phases do not run out of phase to much.
    There are special counters installed for these "Blindleistung". If you have too much phasing out you will have to pay extra money because the generators of the power distribution company
    are extra stressed with this kind of load.
    For industrial customers with heavy loads, power-factor effects (current leading/lagging the voltage) are also of concern.

    But yes, my old days on big CDC systems involved MG sets and chilled water supply to the refrigeration. The STAR-100 was the biggest single machine that I had hands-on experience with. The ETA-10 used liquid nitrogen, but I've always been led to believe that it used substantially less power than the STAR.

    Another nice aspect of 3 phase supplies is the ease of making DC from them. A full-wave rectification setup produces ripple at six times the power frequency (50Hz ->300Hz ripple) and the unfiltered output is largely DC already (87% DC) At 400 Hz, a fullwave setup results in a ripple frequency of 2400Hz. Much less iron in the transformers or variacs as well.

    I suspect a lot of old gear goes the scrapyard because nobody wants it. I was offered the VAX 11/730 that was used at Sorcim in the 1980s. I could not come up with a reason to own the thing, so I let it go unclaimed.

  8. #28

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    Quote Originally Posted by Wildfire View Post
    Thank you

    Would you also agree to the following / or had the same experience: ?

    When you want to have a special system you can have luck and find or get one fast,
    the normal way is that it takes time to find one.
    BUT - if you managed to get one suddenly an other one or multiples pop up out of the fog...
    Oh, yes! Nothing makes rare systems show up faster than having one.


    Quote Originally Posted by Wildfire View Post
    Is there an truck drivers license needed in the US to drive your 5-ton truck ?
    It varies from state to state, with a confusing mess of state and federal laws. California requires a Class B Commercial Driver's License to drive it, even for personal use, based on gross vehicle weight rating, the fact that it has more than two axles, and the fact that it has air brakes. In other states, a Commercial license may not be required if it's not being used for commercial purposes, though the air brakes may complicate things. I don't know the licensing requirements in other states, but I'm aware that California is unusual by requiring a Commercial license based on the vehicle type regardless of how it is used, while many other states only requre Commercial licenses for commercial uses.

  9. #29

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    Quote Originally Posted by Wildfire View Post
    We did have the same problem with one drive which needed also a new LED and photodiode.
    BUT, keep in mind when you still have some data on the drive unit you want to access do not loosen or exchange the whole plastic unit with the components - you will loose the synchron tracking the drive was initiated with.

    If you have luck you only need to clean the LED and photodiode with compressed air and also Q-Tips with isoprop.
    I will give that a try next time we are working on the 11/44.

    Quote Originally Posted by Wildfire View Post
    Nice tools you did rescue for your drives - did you ever have to use them up to now ?
    When I first got the KS10 running the TU45 tape drives did not work. After lots of tedious debugging using the 8080 console processor I found lots of mechanical and plumbing problems in the TU45, and several problems in the TM03. Then I could boot diagnostics, and found that the disks didn't work. I used the suitcase of electronics to make sure that the RP06 disk was OK, so the problem had to be in the RH11, cable, or Massbus<->SMD adapter in the RP06. After a lot more logic analyzer work it turned out to be the Massbus cable. Without the suitcase of electronics I could have been chasing the disk problem for a long time.

    I have a similar problem with the RM03. The diags can see the drive and read its serial number, the drive is ready, but it will not format. I have not fixed this yet.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  10. #30

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    Quote Originally Posted by Chuck(G) View Post
    At 400 Hz, a fullwave setup results in a ripple frequency of 2400Hz. Much less iron in the transformers or variacs as well.
    And that is why the 115VAC in a commercial aircraft is 400Hz.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

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