[QuadList] AVR 3 heads question

Mon Aug 1 16:45:10 CDT 2011

Well, Golly Lee, 

It never is anything simple! 

Only other suggestion I might make is you might try swapping out the MK IV preamp module between the "good" old head and one of the other heads in question. 

At least that would eliminate that part as a cause. 

 I got several Ampex alignment tapes sitting around here. I could mail out one to you to use as a test tape if you dont have one on hand there. 

That and a waveform monitor would help you out a lot in diagnosing. 

larry   
----- Original Message ----- 
From: "lee williams" <lasvegastvengineer at yahoo.com> 
To: "Quad List" <quadlist at quadvideotapegroup.com> 
Sent: Monday, August 1, 2011 5:34:00 PM 
Subject: Re: [QuadList] AVR 3 heads question 

You see the same tearing in demod that you see in the output. 

--- On Mon, 8/1/11, Chill315 at aol.com <Chill315 at aol.com> wrote: 

From: Chill315 at aol.com <Chill315 at aol.com> 
Subject: Re: [QuadList] AVR 3 heads question 
To: quadlist at quadvideotapegroup.com 
Date: Monday, August 1, 2011, 2:13 PM 

Lee 

What does the Demod out look like? 

Chris Hill 

In a message dated 8/1/2011 5:12:28 P.M. Eastern Daylight Time, lasvegastvengineer at yahoo.com writes: 

Hello Larry, 

Sorry but not the problem, 

The closest thing I can describe the effect is white streaks with analog snow in them trailing out like a comet tail from the trailing edge of anything white in the picture. 

No digital blocks, Not a head clog. 

Thanks. 

Lee 

--- On Sun, 7/31/11, LARRY <leodham at centurylink.net> wrote: 

From: LARRY <leodham at centurylink.net> 
Subject: Re: [QuadList] AVR 3 heads question 
To: "Quad List" <quadlist at quadvideotapegroup.com> 
Date: Sunday, July 31, 2011, 6:58 AM 

Hello Lee, 

I have been following some of the back-and-fourth e-mails on your tape playback trouble. 
Here is my two cents worth: 

 I have experienced this problem before. 
The video is tearing in what looks to be square blocks? right?? 
I have encountered that very same effect here on a VR-1200b. It was caused here by the playback equalization. A good way to verify if this is the problem is to go to manual equalization, and turn down(reduce) the EQ one channel at a time. If you see an improvement, then stop the machine, unthread the tape, and look with a magnifier at the drum surface behind each head tip(trailing surface). You may find a small build-up of black-looking stuff behind one, or all, of the head tips on the drum edge surface itself. 
This build-up increases the diameter of the head drum just enough to decrease tip penetration at the head. 
Usual cleaning of the tips will not remove this buildup. Alcohol and a fingernail will. CAREFULLY!! 

 OK, hope this helps, 
larry 
----- Original Message ----- 
From: "lee williams" <lasvegastvengineer at yahoo.com> 
To: "Quad List" <quadlist at quadvideotapegroup.com> 
Sent: Sunday, July 31, 2011 12:24:33 AM 
Subject: Re: [QuadList] AVR 3 heads question 

Hello, 
Answers below questions. 

--- On Sat, 7/30/11, Chill315 at aol.com <Chill315 at aol.com> wrote: 

From: Chill315 at aol.com <Chill315 at aol.com> 
Subject: Re: [QuadList] AVR 3 heads question 
To: quadlist at quadvideotapegroup.com 
Date: Saturday, July 30, 2011, 9:38 AM 

Lee 

How does the RF envelope look on the scope? 
No Scope - I can tell I have plenty of RF with my tracking adjustment. 

How is Vertical lining up with house? 
AVR3 is on internal generator. No difference if I hook up a black source to the machines. 

Do you have an alignment tape?  If so, how does it play and where is the tracking knob? 
Alignment and known good tapes play fine. 
Client has several thousand tapes made in the early 80's (probably on a VR2000) 

Are you using manual or auto tracking? 
Manual normally.  No difference in auto. 

30 lines of black may be that you are one or two head passes off in the vertical realm.  The tearing may be due to the fact that you can not get the head centered on the track perfectly.  

The head assemblies are made so good that they meet SMPTE specifications with in a few hairs.  This is to create interchangeability between machines.  

I would not touch the heads in any way as you will destroy the interchange.  It is a critical factor.  If you saw the recent slide show on here, you see the great deal of care taken to make a head. 

Now the tape you have may have been done in a non standard method.  That is why all the questions.  

I always assume that the tape was poorly made.  Many operations did not do best practices and thus there is a lot of poorly made tapes.  

I know it's the tape that is off. (several thousand of them) 
Now how do I get them transferred short of sending in the weak head to the rebuilder and have him duplicate the deviation were the head is off of true? 

Chris Hill 
WA8 IGN 

In a message dated 7/30/2011 11:56:38 A.M. Eastern Daylight Time, lasvegastvengineer at yahoo.com writes: 

Hay all, 
Have a good one here ??? 

AVR3 Mark XV heads. 

Have some 2" tape that when you try to pull it through the machine will will give you something that looks like video tearing in the whites and slow horizontal jitter. 

If I slam the tracking all the way down, I get a very clean picture, but about 30 lines of black overhead on the screen. 

I see this on all my new(er) heads I get from both Aheadtek and VideoMagnetics. 

I have 1 very warn out head (supplier unknown) that will lock to these tapes 

Has anybody seen this before and is there a way this heads set up can be duplicated? 

Thanks 

Lee 

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