Film-Tech Forum ARCHIVE: Sound Head Azimuth -- Effect of Screw

This is topic Sound Head Azimuth -- Effect of Screw in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Manny Knowles (Member # 1171) on 04-10-2003, 02:00 PM:

I've been doing a lot of A-Chains lately and here's something I've always wondered about...

How come the XY result on my scope goes from being a lovely razor-thin line to being fatter shape when I tighten down the retaining screw for the soundhead lens?

I'm tempted to relax a little and not tighten that screw all the way. It happens on every machine.

(Century/Monee/Westar R-3 type heads with Kelmar reverse-scan LED readers.)

Posted by Bob Koch (Member # 1062) on 04-10-2003, 03:20 PM:

Frustrating, isnt it Manny, all Century`s were prone to this even when I was young using 10kc loops.

Posted by Richard Fowler (Member # 893) on 04-10-2003, 04:10 PM:

It is a given on Century and their clones. I have a special clamp wrench which a old timer Westrex service guy made which makes the job less tedious. The design of the Century holder almost guarantees that the lens tube will rotate when locking down.
Richard Fowler
Kinoton America Inc.

Posted by Don Sneed (Member # 955) on 04-10-2003, 06:34 PM:

Hey Richard, I remember that clamp you are talking about, that was a great tool to use when stereo solar cell first came out, I had one, but lost or left it somewhere....it was great on Century & their clones....thanks for the memory, I forgot about that tool.

Posted by Brad Miller (Member # 2) on 04-10-2003, 08:07 PM:

Manny, when I do A-chains on Centurys I get a pair of 8 inch vice grips and clamp it down (not too hard...just enough to do the job) onto the lens. Then I make sure the set screw is tight, but not locked, such that I can still rotate the lens a little bit.

Do everything like you normally do, but once you have things generally set, tweek the focus by expanding your RTA such that you are only seeing 1db per line. Now tweek the focus to perfection by watching the 16K or 20K reading while still keeping and eye on your azimuth. Once your focus is set to it's optimum, adjust the azimuth by moving the end of the vice grips. This allows you to make much more precision adjustments than putting your fingers on the lens barrel itself and most of the time adjusting the azimuth this way does not throw off your focus. Once you are satisfied with your results, hold the vice grips such that they are not allowed to move while you tighten down the set screw. This way your adjustments do not drift as you are locking things down. [Smile]

Posted by Bob Koch (Member # 1062) on 04-10-2003, 08:45 PM:

Boy, Brad, this is what we used to have to do on WE universal bases[1a reprod and WE206-6 reprods].
It gives me a warm feeling that you people are still struggling with these problems.