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Re: [midatlanticretro] RK05 battery pack for emergency head retraction

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  • B. Degnan
    ... retraction ... http://bitsavers.trailing-edge.com/pdf/dec/disc/rk05/DEC-00-RK05-DA_RK05main ... never ... address. ... plastic ... time ... energy ... By
    Message 1 of 6 , Dec 30, 2012
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      -------- Original Message --------
      > From: "David Gesswein" <djg@...>
      > Sent: Friday, December 28, 2012 9:30 AM
      > To: midatlanticretro@yahoogroups.com
      > Subject: Re: [midatlanticretro] RK05 battery pack for emergency head
      retraction
      >
      > On Thu, Dec 27, 2012 at 11:08:08PM -0500, B. Degnan wrote:
      > > Found from the manual that the batteries are associated with the H743
      > > voltage regulator.
      > >
      http://bitsavers.trailing-edge.com/pdf/dec/disc/rk05/DEC-00-RK05-DA_RK05main

      > > t_72.pdf
      > >
      > > thanks for the tip, I do run the system somewhat frequently, but I
      never
      > > thought about the batteries in each drive's power supply system. They

      > > probably will not leak unless they're incredibly old, I *assume* the
      > > previous owner replaced them, but I will make this a priority to
      address.
      > >
      > They are nickel cadnium so will leak after enough time though not as bad
      > as some other types and only metal below them. The origional has a
      plastic
      > sleve around the entire pack which also contained most leakage. Next
      time
      > I replace them I probably will see if supercaps will provide enough
      energy
      > so the repair is permanent.
      >

      By the way, thanks for the great web site, I really appreciate the time and
      effort put into putting all this together...I am getting closer to having a
      "DEC teletype" set up, by following these directions
      http://www.pdp8online.com/pdp8cgi/query_docs/tifftopdf.pl/CHD/LT33_print_set
      .pdf

      Right now my teletype is stock, and only capable of receiving, but at least
      that part works great now.

      Bill
    • David Gesswein
      ... Thanks ... I was recently looking at that and either missed it or didn t see the schematic for the 4915 board. I did find a version here
      Message 2 of 6 , Dec 30, 2012
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        On Sun, Dec 30, 2012 at 02:31:11PM -0500, B. Degnan wrote:
        >
        > By the way, thanks for the great web site, I really appreciate the
        > time and effort put into putting all this together.
        >
        Thanks

        > I am getting closer to having a
        > "DEC teletype" set up, by following these directions
        > http://www.pdp8online.com/pdp8cgi/query_docs/tifftopdf.pl/CHD/LT33_print_set
        > .pdf
        >
        I was recently looking at that and either missed it or didn't see the
        schematic for the 4915 board.

        I did find a version here
        http://so-much-stuff.com/pdp8/cad/boards.php
        The free version of Eagle will dispaly them. I put a PDF copy here in
        case you don't wish to download Eagle.

        http://www.pdp8online.com/ftp/misc/4915/

        I was reparing some of my spare cards and noticed that the reader run
        drive signal was going way negative at turnoff. When I originally did it
        many years ago I didn't put a diode across the relay coil. Adding that
        made it stop abusing the drive transistor.

        > Right now my teletype is stock, and only capable of receiving, but at least
        > that part works great now.
        >
        Thats good. Hopefully you will have it fully functional. It should
        transmit without the mod, just the paper tape reader may loose characters
        and won't turn on automatically.

        Those bus bars they used on cards for power distribution are annoying
        me. One card had an intermittent where one of the pins has bad solder
        joint. Another card several of the pins were broken off entirly that
        was a pain to fix.
      • Dave McGuire
        ... Seconded! It s great stuff. In fact when I first met you in person at VCF-E in 2011, I felt a bit of celebrity shock . :) -Dave -- Dave McGuire, AK4HZ
        Message 3 of 6 , Dec 30, 2012
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          On 12/30/2012 04:15 PM, David Gesswein wrote:
          >> By the way, thanks for the great web site, I really appreciate the
          >> time and effort put into putting all this together.
          >>
          > Thanks

          Seconded! It's great stuff. In fact when I first met you in person
          at VCF-E in 2011, I felt a bit of "celebrity shock". :)

          -Dave

          --
          Dave McGuire, AK4HZ
          New Kensington, PA
        • David Gesswein
          ... This may have been unclear. It is referring to the reader run mod. Teletypes had lots of options so it can be configured such that it doesn t work. The
          Message 4 of 6 , Dec 30, 2012
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            On Sun, Dec 30, 2012 at 04:15:19PM -0500, David Gesswein wrote:
            > It should
            > transmit without the mod, just the paper tape reader may loose characters
            > and won't turn on automatically.
            >
            This may have been unclear. It is referring to the reader run mod. Teletypes
            had lots of options so it can be configured such that it doesn't work. The
            teletype does need to be set to passive transmit loop (just contact closure).
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