[QuadList] Cap Disc

Wed Jan 27 11:50:53 CST 2010

Thanks George

200 miles north of London am afraid.

Pleased you liked our NHS

Sorry you are having so much trouble getting one of your own (joke)

Everyone edits in insert, so no tape speed changes at the edit point

Used to edit soccer close to deadlines in Assemble (Add On in RCA speak)

If you go back to drop in pictures of the players  vision only into the
interviews after the main edit

and forget to switch to insert you are not very popular, tends roll around
on air

Tape speed 15.625 IPS for PAL  I think

Sort of thing they ask on interviews, but I have never measured it.

Last time I ran a quad up was in Kuwait city a few years back

AVR2's  Not bad machines I had two to fix

Crow bar taking the 20amp fuse hidden on the mother board was the worst
problem

Easy to find hard place to buy a fuse

Trevor Brown

From: georgenann at aol.com [mailto:georgenann at aol.com] 
Sent: 27 January 2010 17:31
To: videovault at sky.com; 
Subject: Re: [QuadList] Cap Disc

Yes Trevor, I must have passed a brainstone earlier, in rec even under
servo/tach control the dia of the cap is a factor.  Tnx fer the wakeup.

Also if I remember correctly, at least with the Ampex machines the cap
actualy freeruns momentarily in an assemble edit.  Also I think this is the
reason that at least at CBS insert edits were never used, always used insert
edits.  I think this stigma has stuck around for some time, even though
insert edits are now OK with the newer machines.

Where are you in the UK?  Was there a while back, the wife took a spill and
busted a bone in her hip and she was in the hosp. for couple weeks in
London.  I couldn't believe the care she received there, it was terrific.
She was in St. Mary's at Paddington. (She screwed up a couple great
cruises).  She is OK, verticle walking OK with cane for time being for bal.
Will be back soon.

Tnx Agn,

George Keller

-----Original Message-----
From: Trevor Brown <videovault at sky.com>
To: 'Quad List' <quadlist at quadvideotapegroup.com>
Sent: Wed, Jan 27, 2010 12:16 pm
Subject: Re: [QuadList] Cap Disc

Can I just throw in an hand grenade

Yes the capstan is locked to the head in record, so tape speed is a product
of capstan diameter only

The dimension stability of tape is not good as temperature changes so does
its length so the track measurements change

Hence helical scan required AST before slo-mo came along just to have
interchange or to play back the tape  recorded at a different temperature

Remember the 7900, machines and poor interchange

Worst case in quad is an assembly edit, where you change from control track
controlled speed to a speed set by the diameter of the capstan

Hence the pip on the ramp on RCA machines, push the toggle and it needs to
hold for 4 seconds or you edit might fall apart, (set Capstan free run)

Trevor Brown

UK

From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of
georgenann at aol.com
Sent: 27 January 2010 16:40
To: quadlist at quadvideotapegroup.com
Subject: Re: [QuadList] Cap Disc

-----Original Message-----
From: Don Norwood <dwnorwood at embarqmail.com>
To: Quad List <quadlist at quadvideotapegroup.com>
Sent: Tue, Jan 26, 2010 10:42 pm
Subject: Re: [QuadList] Cap Disc

New replies in GREEN below.....

----- Original Message ----- 

From: georgenann at aol.com 

Subject: Re: [QuadList] Cap Disc

-----Original Message-----
From: Don Norwood <dwnorwood at embarqmail.com>

My post about changing the speed of the capstan was referring to your
description of what was done to the pulleys on VR-2000 or 1200 machines.
Unless I'm missing something, that would change the tape speed, which in
turn changes the video track specifications.

Well, it might change the tape speed if it weren't for the servo, it just
put it into a slightly different range, one the servo seemed to like a
little better.

Agreed, but ONLY for playback where the capstan speed is controlled by the
servo.  If the machine is for playback only, no problem, although I would
have guessed that an electronic modification would have been much easier.
My concern would be in record, where the capstan is fed a fixed frequency,
and therefore the speed is affected by the mechanics.  The servo has no way
of knowing what the actual velocity of the tape is in record.  If it has
been changed by a mechanical modification, then the track alignment will be
non-standard.

The capstan is always under servo control.  It is derived from the head
tach. The head is locked to V, either re or incoming video.

Nobody ever came up with an electronic mod for this, I don't know why, will
have to think about this.

I remember those damn round chips in bd 9, 10.  I whish they had left them
alone, they made it hard to get a scope in there to troubleshoot. Board 14
was reframing?? I don't recall having any problem with it so left it alone.

Yes, 14 is mostly reframing.  After many years, the relays on the board can
be problematic and cause trouble with normal servo operation.

You sure have a great memory, you should write a book on the history of the
servo, kind of like the big Rolex or Vibroplex history books. (Just
kidding).  Tnx fer the info it is interesting.  I didn't get into the
machines till the 70's.

I got into the machines in the early 70's, and it's not my memory that's
great, it's just that I have collected as much reference material as
possible.  Since I still work on these, some things are more easily recalled
than others, but I still have to look up a lot of stuff!

Don

Lucky guy, it sure was fun.

Tnx Agn

DE GK

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