[QuadList] What is it????

[Don Norwood]

And once again, Chris is the winner!!!!

Bill Carpenter told us about a mini buffer (TBC) that was designed for the VR-1400, a VR-1200 fitted with the new TBC to replace Amtec/Colortec/Velcomp/ProcAmp, but the machine never became a product due to the development of the AVR-2. However, the TBC design went on to become the TBC-790, intended for use with the VPR-7900.

Ampex used some of the modules from the AVR-1 as well as some newly designed modules, but the card cage design of the TBC-790 was different in several respects from the AVR-1.  For one thing, there were coax connectors in the AVR-1 back plane, but not in the TBC-790, so the coaxial connections that would normally have mated with connectors on the rear of the modules were instead routed to connectors on the front panel.  I suspect that was done to save cost, however, another difference has always puzzled me.  For whatever reason, the card frame in the TBC-790 is "upside down and backwards" as compared to the AVR-1, so the re-purposed cards (which were not re-labeled) have connector pin numbers that are opposite of what you would expect.  

Otherwise, the mechanical design of the modules is unchanged except for the extruded aluminum handle that runs the length of the module instead of the "loop" handle on the AVR-1.  It's the same design as used on the AVR-2, VPR-7900 and VPR-7800.  Here's a pic of the module installed in a TBC-790 with jumpers between modules taking the place of the back-plane connectors in the AVR-1.



Interestingly, in the TBC-790 manual, for the modules that were "borrowed" from the AVR-1, there was no re-working of the drawings to match the new configurations for the TBC.  The pages from the AVR-1 manual were simply copied, ignoring the changes in the mechanical design and the pin numbering!

Don Norwood
Digitrak Communications, Inc.
www.digitrakcom.com
  ----- Original Message ----- 
  From: Chill315 at aol.com 
  To: quadlist at quadvideotapegroup.com 
  Sent: Friday, May 13, 2011 10:37 PM
  Subject: Re: [QuadList] What is it????


  Then there is only one answer.  It is for the TBC that was designed for the VR-7900 type A machine.  

  Chris Hill

  In a message dated 5/13/2011 10:25:51 P.M. Eastern Daylight Time, dwnorwood at embarqmail.com writes:
    Hi Chris:

    No, I didn't say it was for a quad, just that it was "firmly rooted in quad history".  You got part of that answer right!  And Park got the 1" TBC part right.  And Bill Carpenter told the whole story not too long ago including how this fits with the "quad that never was".  I figured one of you guys would put the pieces together!

    Don Norwood
    Digitrak Communications, Inc.
    www.digitrakcom.com  
      ----- Original Message ----- 
      From: Chill315 at aol.com 
      To: quadlist at quadvideotapegroup.com 
      Sent: Friday, May 13, 2011 10:13 PM
      Subject: Re: [QuadList] What is it????


      Yes I did notice that the module was missing the pull handle.  The card does have the 28 pin connector that the AVR-1 used.  The 63.5 micro second delay line is used in the drop out compensator of the AVR-1.

      The front connectors are what throw me for a loop.  So I am at a loss.  

      It is for a quad you say so that does not leave much left.

      Chris Hill

      In a message dated 5/13/2011 10:09:05 P.M. Eastern Daylight Time, dwnorwood at embarqmail.com writes:
        Hi Chris:

        Almost a winning answer, maybe the best so far.....but you'll notice that this module design (mechanical, not electrical) is slightly different from the AVR-1.

        Don Norwood
        Digitrak Communications, Inc.
        www.digitrakcom.com  
          ----- Original Message ----- 
          From: Chill315 at aol.com 
          To: quadlist at quadvideotapegroup.com 
          Sent: Friday, May 13, 2011 9:54 PM
          Subject: Re: [QuadList] What is it????


          This is the one line delay module that was used in the AVR-1 / ACR-25.  

          Chris Hill
          WA8IGN



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