[QuadList] ACR-225 (was 1" Machine glue)

[Trevor Brown]

Dennis

Sorry I did not explain myself too well

The RCA color time base corrector dumps any errors it cannot cope with into
the mono TBC this dump signal is called THAF
The Mono TBC dumps any errors it cannot cope with into the servo this error
is called THA
This extend the range of the small fast TBC's that can cope with quad
errors, by operating a closed loop

You clamp the error signals to mid range until the servo locks and then
unclamp and it all stays locked

On the TCR you have one TBC and two servo's so there is still a THAF loop
but no THA loop which mean the mono TBC cannot spill into the servo to
centre itself (not a closed loop) and as a result has a poor range and
unlocks on air

By stand alone I meant AVR 2 style TBC which has a greater window and will
run independent of the servo's

The Helical TBC's are big window two but designed to deal with slow errors
and so are as you say no good for quad.

The sharing of a TR70 signal processing with a TCR (we did not have a 60) is
called master kit and you end up with a TR70 with a small TBC window
Which spoils its performance too.

It's a big mod and it spoils your reel to reel machine, which cannot operate
when you are using the TCR, we gave up and bought an SPU (TR600) modules,
not as good as the SPU based on TR70 modules

TrevorB
UK Member





-----Original Message-----
From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Dennis Degan
Sent: 03 February 2010 12:15
To: Quad List
Subject: Re: [QuadList] ACR-225 (was 1" Machine glue)


		On Feb 2, 2010, at 12:29 PM, Trevor Brown wrote:

 > Needed a standalone TBC so it would not get upset when it switched 
decks, But RCA did not have one and they would have gone out of 
business rather
than fit a brand X TBC  Oh sorry they did go out of business

		I say:

	But not because of the TCR-100.  They sold a crap-load of them.  And

stations made a lot of money using them.
	I sorta disagree with you about their needing a standalone TBC.
This 
was still a quad machine and quad's timebase errors were quite 
different from the errors corrected by standalone TBCs of the time.  
Nearly every one of those standalone TBCs were made for helical VTRs 
which had slower-changing and larger-deviation timing errors.  It made 
sense for RCA to use what they had in use on TR-60's and TR-70's of the 
era.  Those systems actually worked quite well.
	TCR-100 did have one marketing advantage over ACR-25 which made it 
desirable in many smaller markets:  The machine could share its signal 
system and error correction system with a co-located TR-60.  This saved 
the stations a lot of money.  Though I never worked with one of these 
versions of the machine, I could see how this feature would make TCR 
popular with station owners (and probably ONLY with station owners).

			Dennis Degan, Video Editor-Consultant-Knowledge Bank
	  					NBC Today Show, New York


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