[QuadList] Weekend Mystery Pic for 3/12/11

[Don Norwood]

There has been deafening silence on this pic except for the reply from Chris and an off-list, correct answer from David Crosthwait.  Congratulations again David!  With the weekend coming to a close, I'll go ahead and post the answer along with the "rest of the story".

The control is the tracking adjustment on an AVR-3.  The story behind the control is really interesting and was told to me a while back by fellow list member Bill Carpenter.  Below is what Bill had to say.......

This control was added in the "massive retrofit", which I had to start to correct all the problems.

The tracking control was there, but we needed a front panel pushbutton, which turned on and off the very poor autotracking. 

I can't remember whether it turned the autotracking on and off, or whether it just told it to track again!

The control came from the Tektronix 7000 series scope, and I arranged to buy the controls from Tek, to solve the problem, and not add another control as part of the retrofit.

The original design by a well known industry servo design engineer, would turn ON the dither, find track center, and then freeze that position, and turn dither OFF.

This is fine for a long tape which was to playback "to air". 

The Hollywood post production marketplace had over 50 machines, and they found out that the source reels which would have many "takes", a few seconds long, maybe 30 seconds at best would only track on the first "take", and then mistrack on most of the others, since the Record machine had been started and stopped after every take!

This all happened because the Product Manager had no experience in the Hollywood marketplace, and was also worrying about the Editing system we were going to buy from Central Dynamics in Canada, but that's another long sad story, for another day!

We made the Autotracking work, after the retrofit, with the control which I sourced from Tek.
.........................

So, when Chris wondered if it might be part of a vectorscope, he was almost on the right track!  I have some of these controls on a Tek 7000 series instrument, but this pic was from an AVR-3 and was sent to me by list member John Pommon.  Thanks John!  A bit of work in Photoshop eliminated the "Tracking" label on the panel and turned it into B&W to hide the panel color.  The AVR-3 doesn't get much discussion on the list, but it had been active recently so I thought it would be a good time for this one.  Next week, off in a different direction........

Don Norwood
Digitrak Communications, Inc.
www.digitrakcom.com
  ----- Original Message ----- 
  From: Don Norwood 
  To: Quad List 
  Sent: Saturday, March 12, 2011 12:40 PM
  Subject: [QuadList] Weekend Mystery Pic for 3/12/11


  For this weekend's challenge, identify the function of this control and what  machine it is on.  As far as I know, it is the only control of this design on any quad machine.



  Don Norwood
  Digitrak Communications, Inc.
  www.digitrakcom.com
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