[QuadList] TBC

Sat Apr 30 10:22:54 CDT 2011

The AMTEC worked on a different principle than a digital TBC.  The  AMTEC 
used a sample the leading edge of sync and compare it to house  method.  Then 
immediately change the variable delay line after that.   That is why the 
switch pulse has to be in the front porch of the sync  interval.  If you do it 
in the back porch, then the relationship of the  video would possibly 
change on the line with the switch.  Leading edge has  to be used as sync width 
varies between sources.  

It would never have to digitize the signal like the TBC of today.  

Digital TBC's work in many different ways.

Chris Hill
WA8IGN

In a message dated 4/30/2011 9:54:41 A.M. Eastern Daylight Time,  
georgenann at aol.com writes:

Thank You, David,

Your memory is better than most TBC's.

Roger on the head switch point, that is where most digital TBC's  failed.  
I don't understand why a digital tbc with a 8 or 16 line window  can't seem 
to handle it but the Ampex Amtec could. 

73,

George Keller

-----Original  Message-----
From: David Crosthwait <david at dcvideo.com>
To: Quad  List <quadlist at quadvideotapegroup.com>
Sent: Sat, Apr 30, 2011 9:07  am
Subject: Re: [QuadList] TBC

George,  

No I did not try the suppression pulse mode. The ability to handle a head  
switch is the key as far as I am concerned. Also, some of these boxes don't  
like incoming noise and spiky video. Yes, I do recall the 516, but I seem 
to  recall that this was more suited for 3/4" processing and did not have 
direct  color processing. Have the spec. sheets in the file I think. The 520 
and 590  had more memory also perhaps. I think these products hit the market 
in 1974 or  so, maybe later?. When you open up these devises to take a peak, 
it's a  massive amount of circuitry, top and bottom of the unit, that is now 
 approaching 40 years in age. They have a lot of pots to adjust, which need 
 constant tweaking. 

NBC Burbank had a 590 on a TR 70A for a month tryout at one time. That  was 
the duration of that unit as it went back. I did operate a VR 1200/CVS520  
on an NCAA Basketball game in Dayton Ohio one time (don't recall who's truck 
 but may have been Multimedia/WLWT). It did the job it was supposed to do, 
but  that was 1979.

Best Regards,

David Crosthwait
DC Video
_DAVID at DCVIDEO.COM_ (mailto:DAVID at DCVIDEO.COM) 
_WWW.DCVIDEO.COM_ (http://www.dcvideo.com/) 

On Apr 30, 2011, at 5:16 AM, george keller wrote:

<WBR>Thank You!! Great me  The other one was perhaps a  516.  Did you try 
the suppression pulse route and did it help at all  with any other TBC's? I 
tried it with Sony TBC2000 and 1000. Try monochrome?  I really had no luck to 
mention withe either one.

MNY TNX,

George Keller

-----Original  Message-----
From: David Crosthwait <_david at dcvideo.com_ (mailto:david at dcvideo.com) >
To: Quad List  <_quadlist at quadvideotapegroup.com_ 
(mailto:quadlist at quadvideotapegroup.com) >
Sent:  Fri, Apr 29, 2011 8:33 pm
Subject: Re: [QuadList] TBC

George,  

That was the CVS 520 and the later CVS or Harris 590. Been there, done  
that with those boxes!

Best Regards,

David Crosthwait
DC Video
Archived Media Transfer and Re-mastering Services

Offices located at:
177 West Magnolia Blvd.
Burbank, CA. 91502
818-563-1073
818-563-1177 (fax)
818-285-9942 (cell)

_DAVID at DCVIDEO.COM_ (mailto:DAVID at DCVIDEO.COM) 
_WWW.DCVIDEO.COM_ (http://www.dcvideo.com/) 

On Apr 29, 2011, at 3:34 PM, george keller wrote:

CVS had a DTBC it had either a 16 or 20 in it's model number which  had an 
optional extra wired in small board mod for segmented  machines.  There may 
still be some around, but look for the  board.  AF put one in a 1200 D or 
E(?) and made it smaller than an  AVR 2, you could roll it around anywhere.

I have also played wilth DTBC's and the 2000 also with no real  luck.  
Widening out the supression pulse and moving it around showed  some noticable 
results, but no cigar.  Might not have too bad in  mono, but never tried it.

George Keller

-----Original  Message-----
From: Don Norwood <_dwnorwood at embarqmail.com_ 
(mailto:dwnorwood at embarqmail.com) >
To:  Quad List <_quadlist at quadvideotapegroup.com_ 
(mailto:quadlist at quadvideotapegroup.com) >
Sent:  Fri, Apr 29, 2011 5:53 pm
Subject: Re: [QuadList] TBC

Shai: 
 The design is very different.  I have tried many different models, not 
 expecting them to work, but just out of curiosity.  NONE of them, from 
 older, early generation TBC's to very modern designs will work.  There are 
 two main problems.....first is the different nature of the timing error 
 between segmented and helical, and second is that many of the early 
designs 
 as well as later and less expensive models were not designed for use with 
 direct color recovery.  They rely on the heterodyne processing in the VTR 
to 
 recover the color signal, and that's the market that most of the TBC's 
were 
 designed for.

 Merlin used several different models of NEC TBC's but I believe most of 
them 
 required some degree of modification.  They also used an Adda VW-2 and an 
 Ampex TBC-800, both with some mods .  You can find info on these on our 
 website on the Merlin Literature page.

 Don Norwood
 Digitrak Communications, Inc.
 _www.digitrakcom.com_ (http://www.digitrakcom.com/) 

 ----- Original Message ----- 
 From: "Shai Drori" <_srdbx at netvision.net.il_ 
(mailto:srdbx at netvision.net.il) >
 To: <_quadlist at quadvideotapegroup.com_ 
(mailto:quadlist at quadvideotapegroup.com) >
 Sent: Friday, April 29, 2011 11:32 AM
 Subject: Re: [QuadList] TBC

 > Why is that? I thought that maybe an old TBC might be able to handle 
this? 
 > Has anyone tried this before? Also, what do I do with LB on an AVR-2? 
Ken 
 > Zin looks very busy at the moment I doubt he'll have time for me now to 
 > talk about his cards. Is the avr-1 and tr-70 the only multistandard 
 > machines?
 > Shai
 >
 > On 29/04/2011 11:00, _quadlist-request at quadvideotapegroup.com_ 
(mailto:quadlist-request at quadvideotapegroup.com)  wrote:
 >> The problem is that the TBC must be designed for segmented scan.  VERY 
 >> FEW
 >> ever were, and I'm not aware that any on the market today or in recent 
 >> years
 >> will work for anything other than non-segmented (helical) scan.
 >>

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