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Weekend workshop

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  • David Gesswein
    Does anyone wish my assistance? My area is PDP-8 s and general component level repair. I can bring various general purpose test equipment/tools. Otherwise I
    Message 1 of 9 , Jun 10, 2014
      Does anyone wish my assistance? My area is PDP-8's and general
      component level repair. I can bring various general purpose test
      equipment/tools.

      Otherwise I will do further work on my MFM hard drive emulator/reader. I
      won't have the PCB yet but will be bringing my wirewrap prototype if anybody
      wishes to try it with their stuff.
    • billdeg
      Dave, What is the sweet spot of hard drive specs for this project? I may have a drive or two I can bring for testing if you need one. Bill
      Message 2 of 9 , Jun 10, 2014
        Dave,
        What is the sweet spot of hard drive specs for this project?  I may have a drive or two I can bring for testing if you need one.
        Bill
      • David Gesswein
        ... In theory it should be able to handle any size MFM drive. The biggest I have tested with is 70 MB. I haven t tried to do RLL yet though have one drive I
        Message 3 of 9 , Jun 10, 2014
          On Tue, Jun 10, 2014 at 07:06:54PM -0700, billdeg wrote:
          > Dave,
          > What is the sweet spot of hard drive specs for this project? I may have
          > a drive or two I can bring for testing if you need one.
          >
          In theory it should be able to handle any size MFM drive. The biggest I have
          tested with is 70 MB. I haven't tried to do RLL yet though have one drive
          I will bring if I get to that. Need is too strong but if you feel like
          bringing a drive I'll see if it works with it or needs further tweeking.
        • retro
          On 6/10/2014 9:48 PM, David Gesswein djg@pdp8online.com ... My plans to attend are tentative for mostly personal reasons. I m considering bringing a PDP 11/04
          Message 4 of 9 , Jun 11, 2014
            On 6/10/2014 9:48 PM, David Gesswein djg@...
            [midatlanticretro] wrote:
            > Does anyone wish my assistance? My area is PDP-8's and general
            > component level repair. I can bring various general purpose test
            > equipment/tools.
            >
            > Otherwise I will do further work on my MFM hard drive emulator/reader. I
            > won't have the PCB yet but will be bringing my wirewrap prototype if anybody
            > wishes to try it with their stuff.

            My plans to attend are tentative for mostly personal reasons.

            I'm considering bringing a PDP 11/04 I acquired not long ago. So I'd be
            interested in your DC regulated supply to restore the electrolytics in
            the power supply.

            SOmeone posted interest in commodore items to acquire. I have several
            C64 books, some common but all somewhat technical, to make available.

            Also a Timex/Sinclair 2068 (Z80 game computer) and several books and
            some carts & tapes. I'll post that separately as an OT offer, which I'd
            consider selling outside the workshop.

            Herb

            --
            Herbert R. Johnson
            http://www.retrotechnology.com OR .net
          • retro
            On 6/11/2014 1:03 PM, retro ... http://www.retrotechnology.com/dec/1104_herb.html Comments welcomed, partcicularly about that SMS FD1100I controller card.
            Message 5 of 9 , Jun 12, 2014
              On 6/11/2014 1:03 PM, retro
              > I'm considering bringing a PDP 11/04 I acquired not long ago. So I'd be
              > interested in your DC regulated supply to restore the electrolytics in
              > the power supply.
              >
              http://www.retrotechnology.com/dec/1104_herb.html

              Comments welcomed, partcicularly about that SMS FD1100I controller card.
              Email me directly via that Web page, no sense filling this list with
              nuts and bolts chatter.

              herb
              --
              Herbert R. Johnson
              http://www.retrotechnology.com OR .net
            • billdeg
              The three racks are connected not by a bolt but by a simple slot and post , larger but similar to what you d see in a modern server rack arm. These three did
              Message 6 of 9 , Jun 12, 2014
                The three racks are connected not by a bolt but by a simple "slot and post", larger but similar to what you'd see in a modern server rack arm.  These three did not disconnect easily, I will need a crowbar or something.  Is there is best way?  Don't want to break.

                Any advice for disconnecting?  I plan to use a crowbar unless I get better advice...  I need to know before the movers arrive tomorrow early afternoon.  I have successfully disconnected the cables.  It's late notice but if anyone wants to meet me in Wilmington, DE tomorrow around lunch let me know.

                http://vintagecomputer.net/pictures/2014/dec_11-44_system_rear.JPG
                http://vintagecomputer.net/pictures/2014/dec_11-44_system_front.JPG
                 

                Bill
              • ian_primus
                Yeah - they re joined just by the retainers that would normally hold the side panels on. Normally, on a single rack, the side panel lifts up and pops off -
                Message 7 of 9 , Jun 12, 2014
                  Yeah - they're joined just by the retainers that would normally hold the side panels on. Normally, on a single rack, the side panel lifts up and pops off - usually it requires a fair bit of force to do so, as they haven't been moved in 30 years and they're usually bent. A trick I tend to use is to put a block of wood under the edge of the side panel such that the entire cabinet is being supported by the side panel on that one side, and push down on the cabinet. The additional weight of the computer will make it easier to pop the stubborn panel off.

                  When two cabinets are joined together side by side, they use a special "joiner panel" - that's simply a side panel with two sets of hooks to slip into two cabinets simultaneously. This can be hard to separate because, effectively, what you have to do, is lift that center panel UP, while the cabinets stay on the floor. Raising one entire cabinet up is difficult, because then you torque the panel sideways and might wedge it in worse.

                  Again, if you can somehow wedge a block of wood under just that center panel, you might be able to pop the panel up and out of the center. Also, ensure that neither of the cabinets is forced at an angle or in any way that would wedge that center panel. With a two cabinet system, you can usually have one guy lift up on one cabinet while another holds down the other, and get them to separate, then remove the panel from the one it stayed on. Still, this can be annoying and difficult to do, and can wedge it worse. I've never had to separate a three cabinet system before, and, I think this is the first time I've seen a good picture of that joiner panel to join a short and a tall cabinet together.

                  Good luck in your quest - but it should be doable, just might take some creative leverage.

                  -Ian
                • Paul Birkel
                  While I ve not personally seen one of these multi-join-ups I can add that in the single stand-alone corporate-cab it is the case that the side panels don t
                  Message 8 of 9 , Jun 12, 2014
                    While I've not personally seen one of these multi-join-ups I can add that in the single stand-alone corporate-cab it is the case that the side panels don't "just slide off" because they are overlapped along the bottom by the hardware used to secure the lower skirt(s).  That hardware can protrude laterally to create a lip that prevents the side-panel from moving upwards in order to disengage the locking-tabs.  And it seems that there is some variation on the hardware over time, so you have to pay very close attention.
                     
                    I almost achieved the crow-bar stage in my first encounter with one of these before I disassembled enough bits (really, "everything in sight") to realize where the interference was occuring.  I did use plenty of wood-block and mallet first, but eventually decided that surely-I-was-doing-something-wrong it-shouldn't-be-this-hard.  I was right ... after being wrong.  Strongly recommend that you remove *all* skirt-associated hardware before attempting to "muscle" it further.  or at least convince yourself that there in *no* lip-interferance anywhere.  Of course, the design of the joiner-panel may make all of these physical considerations moot.
                     
                    Anyway, agree that it's a tight fit.  Suggest a little WD-40 into the slots if you can reach them; you'll definitely benefit from a long tube to get the juice where it will do the most good.  They do get rusty in there, but then all the DEC HW from that era that I've had direct experience with has been rusty, sad-to-say :-<.


                    On Thu, Jun 12, 2014 at 7:39 PM, ian_primus@... [midatlanticretro] <midatlanticretro@yahoogroups.com> wrote:
                     

                    Yeah - they're joined just by the retainers that would normally hold the side panels on. Normally, on a single rack, the side panel lifts up and pops off - usually it requires a fair bit of force to do so, as they haven't been moved in 30 years and they're usually bent. A trick I tend to use is to put a block of wood under the edge of the side panel such that the entire cabinet is being supported by the side panel on that one side, and push down on the cabinet. The additional weight of the computer will make it easier to pop the stubborn panel off.


                    When two cabinets are joined together side by side, they use a special "joiner panel" - that's simply a side panel with two sets of hooks to slip into two cabinets simultaneously. This can be hard to separate because, effectively, what you have to do, is lift that center panel UP, while the cabinets stay on the floor. Raising one entire cabinet up is difficult, because then you torque the panel sideways and might wedge it in worse.

                    Again, if you can somehow wedge a block of wood under just that center panel, you might be able to pop the panel up and out of the center. Also, ensure that neither of the cabinets is forced at an angle or in any way that would wedge that center panel. With a two cabinet system, you can usually have one guy lift up on one cabinet while another holds down the other, and get them to separate, then remove the panel from the one it stayed on. Still, this can be annoying and difficult to do, and can wedge it worse. I've never had to separate a three cabinet system before, and, I think this is the first time I've seen a good picture of that joiner panel to join a short and a tall cabinet together.

                    Good luck in your quest - but it should be doable, just might take some creative leverage.

                    -Ian


                  • billdeg
                    It s the horizonal fit rack to rack connectors, not vertical. But I told the movers about it, we ll see how they do with it. I am on stand-by to get over
                    Message 9 of 9 , Jun 13, 2014
                      It's the horizonal fit rack to rack connectors, not vertical.  But I told the movers about it, we'll see how they do with it.  I am on stand-by to get over there when they call me
                      bd
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