[QuadList] VR-1200B Daily Servo Set UP

[Don Norwood]

The Intersync servo was certainly well known for not being the most stable device.  However, for 1200's or 2000's still in operation, there are improvements that make a huge difference.  As David pointed out, there were revisions made thru the years, obviously in part as a result of user input, and also due to improvements in components and designs.  Some of the later Intersync systems are much more stable than their earlier cousins.

To further improve the stability, the use of a precision power supply for the servo system not only improves the servo performance, but also can make a small improvement in the signal system.  The standard Ampex 1200 had a common +/-12vdc supply for the signal system and the servo.  It was a simple design that did not provide the best regulation or stability.  By providing a separate, highly regulated and stable supply for the servo, the stability of the servo improved and the s/n of the signal system was slightly improved by removing the servo load from the common supply.  Merlin offered such a mod, or it can be done fairly easily today using modern supplies.

There are also some components within Intersync that can be replaced with newer parts that are much more stable than the 40 year old originals.  On a machine where these mods have been done, it is rarely necessary to do the daily setup, even when the machines are cycled on and off or experience other temperature shifts.  I can apply power, load a tape, push play and expect full lock in 4 sec without any adjustments.

Obviously, at the time that most of the quads were in service, they didn't have the benefit of these improvements.  I don't know how many of the Merlin kits were installed or how others may have addressed the servo problem, but obviously the ritual of bowing to the Intersync was a well know exercise of the day!

Don
  ----- Original Message ----- 
  From: dcfwtx at aol.com 


  In the mid 60's, CBS and NBC had individual modifications to the VR 2000 that they frequently shared. CBS was notorious for modifying just about everything when it came into the door. Many of these mods were incorporated into later production models, such as the VR 2000Bs.

  David Crosthwait
  www.dcvideo.com





  -----Original Message-----
  From: Guy Spiller 


  Wow, does this bring back memories...even though I was 19 at the time. 
  I think my knees are starting to hurt again after seeing this! LOL 
  Guy 
   
  Chill315 at aol.com wrote: 
  > We had this on a 5 by 7 card that was taped inside the door below the > monitor on the sidecar. It worked and we had very few problems. > Thought that I would pass it on. 
  > > Chris Hill 
  > > > > VR-1200 B Series Inter-Sync Systems Daily Set Up 
  > > PRIOR TO ANY ADJUSTMENT, LET HEAD SPIN FOR ABOUT 30 MINUTES 
  > > Do in the following order 
  > > Reference Discriminator 
  > With head spinning, adjust R28 on board 2 for zero. 
  > > Drum Oscillator 
  > > With head stopped, adjust Drum oscillator R21 on board 6 for stable > wave form. 
  > > Tach Discriminator 
  > > With Drum spinning, set R85 on board 6 for zero 
  > > Capstan Oscillator 
  > > Set Capstan Oscillator for steady wave form 
  > > Capstan Discriminator 
  > > With Machine in Record, set R1 on board 12 for zero 
  > > Drum Tach position 
  > > With Machine in Record, verify that tach is at correct position on > demod using pulse cross. 
  > > 
  > If doing editing, 
  > > Turn Editor on 
  > > Set H Phase to zero with input that you are using when source is timed 
  > > Set Tach Phase to same position as was used in RECORD mode 
  > > Note: If original tape was as recorded with incorrect Tach phase, set > Tach phase to match the incorrect tape. > > H phase sets quality of in-going edit and Tach Phase sets quality of > out going edit. Do a test edit if desired and check AMTEC error for > quality of edits. 
  > 
  > ------------------------------------------------------------------------ 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://quadvideotapegroup.com/pipermail/quadlist_quadvideotapegroup.com/attachments/20090823/2e189705/attachment-0005.html>