[QuadList] Blanking Issues

[Wayne Watson]

It was in the SMPTE standard. Ampex made it an option and Sony made it standard. The concern was that something in the future might need the V.I. However in type C only lines 4 to 14 were missing so VITC and VITS were still there. I think there was also an issue where Sony did not want tp pay re a patent Ampex had on control track update (or something like that)and needed the V.I. to do it their way. Can anyone shed more light on that?
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From: quadlist-bounces at quadvideotapegroup.com [quadlist-bounces at quadvideotapegroup.com] On Behalf Of Scott Thomas [scottgfx at mac.com]
Sent: Saturday, February 06, 2010 11:59 PM
To: Quad List
Subject: [QuadList] Blanking Issues

Talking about Type-C for a moment; I can't remember if it was Sony or Ampex (or both?), but they had a separate "sync" head on the scanner. I'm assuming that was to have a clean sync pulse on the head switch? A problem obviated by a TBC?

Scott Thomas

On Feb 6, 2010, at 5:20 PM, Don Norwood wrote:

Hi Park:

All of the Type-A 1" machines up thru the VR-7800 had the switch above the vertical interval.  The VPR-7900 was the first to place it in the vertical.  Remember also that the Type-A machines are single head, so there is more than a "switch", there is a dropout for several lines.  The VR-660 is a 2-head design so there is a switch and no dropout.

When Sony made their first 1/2" machines, there was apparently some "reverse engineering" done on their Ampex predecessors.  Although the Sony machines were 2-head, they had a "blanking" circuit that covered up the switching point and produced a totally blank area in the same location as the Ampex Type-A.  There was no logical reason for that other than replicating the output signal of the Ampex.  The practice was discontinued in subsequent models.

Don Norwood
www.digitrakcom.com<http://www.digitrakcom.com>
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