Second Generation Speed

[David Crosthwait]

Subject change 3rd time.

Begin forwarded message:

> From: David Crosthwait <david at dcvideo.com>
> Date: September 23, 2014 9:57:44 AM PDT
> To: Quad List <quadlist at quadvideotapegroup.com>
> Subject: Re: [QuadList] Capstan questions
> 
> Hello Chris,
> 
> If the VTR in which new time code is recorded to is locked to the same sync source as the time code generator and both stay locked for the duration, then they should be the same code throughout to the frame. If not, then upon play back of the VTR locked to house sync, the time code waveform may show drift with reference to house sync. This is an especially troublesome scenario when editing 2" tapes i.e. CMX. One has to re-stripe the sections where code is NG.
> 
> Best Regards,
> 
> David Crosthwait
> DC Video
> Preservation Level Videotape Transfers and More!
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> 
> 
> 
> On Sep 23, 2014, at 7:41 AM, Chris Hill via QuadList wrote:
> 
>> 
>> 
>> From: Chill315 at aol.com
>> Date: September 23, 2014 7:41:29 AM PDT
>> To: quadlist at quadvideotapegroup.com
>> Subject: Capstan questions
>> 
>> 
>> I always wondered what the tolerances were for the sizes of a capstan.  Reason for the question.
>>  
>> I was remembering that on a VR-1200 the same tape played on two different machines would show a positive or negative capstan error.  Then we time coded the same tape on the two machines and there was a difference in the final time code number by several seconds.  Thus there had to be a small difference over the 32 minutes of tape. 
>>  
>> Now capstan sizes.  The VR series used basically the same size capstan.  As well as the AVR-2.  the AVR-1, ACR-25 used the vacuum capstan that was substantially larger.  As I never inspected an AVR-3, I can only look at the pictures and surmise that it was similar to the AVR-1 capstan.  What were the tolerances?  Were the vacuum capstans a variable that enters into the equation?  I only worked with an ACR so do not have the experience with the AVR-1.
>>  
>> Does anyone have insight for this set of questions?
>>  
>> Then the last question is we all know that the tape does have an abrasive quality to it.  Being that the back side touches the capstan and front side touches the roller, the tape would not wear down the capstan like an audio head or guide.  Yet I have seen a number of capstans that show a polished portion that could be taken for wear.  Has anyone ever had to replace a capstan due to excessive wear?
>>  
>> Chris Hill
>> WA8IGN
>> 
>> 
>> ______________________________________________
>> Please trim posts to relevant info when replying.
>> 
>> Change subject to reflect thread direction. Thanks.
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>