[QuadList] TBC

Sun May 1 10:03:56 CDT 2011

Roger That, 

If I remember correctly, in a DTBC the sampling was tied to subcarrier, (Pseudo Subcarrier) which one might
presume would be right on top of everything that is going on. (The PLL in the TBC-1000  had a pot on one of the first boards was very critical, if it was off just a couple degrees the whole thing would quit all together, I never liked that pot.)

My main point was always keep "Maintenance" in mind, especially when buying an old machine.  Sometimes just moving it can cause many problems.

DE,

George Keller

-----Original Message-----
From: Chill315 <Chill315 at aol.com>
To: quadlist <quadlist at quadvideotapegroup.com>
Sent: Sat, Apr 30, 2011 11:23 am
Subject: Re: [QuadList] TBC

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
WWW.DCVIDEO.COM

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

Thank You!! Great memory.  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>
To: Quad List <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
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>
To: Quad List <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 
xpecting them to work, but just out of curiosity.  NONE of them, from 
lder, early generation TBC's to very modern designs will work.  There are 
wo main problems.....first is the different nature of the timing error 
etween segmented and helical, and second is that many of the early designs 
s well as later and less expensive models were not designed for use with 
irect color recovery.  They rely on the heterodyne processing in the VTR to 
ecover the color signal, and that's the market that most of the TBC's were 
esigned for.
Merlin used several different models of NEC TBC's but I believe most of them 
equired some degree of modification.  They also used an Adda VW-2 and an 
mpex TBC-800, both with some mods .  You can find info on these on our 
ebsite on the Merlin Literature page.
Don Norwood
igitrak Communications, Inc.
ww.digitrakcom.com
----- Original Message ----- 
rom: "Shai Drori" <srdbx at netvision.net.il>
o: <quadlist at quadvideotapegroup.com>
ent: Friday, April 29, 2011 11:32 AM
ubject: 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 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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