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» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Degaussing for Mag Film (Page 1)

 
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Author Topic: Degaussing for Mag Film
Brad Morris
Film Handler

Posts: 29
From: Los Angeles, CA, USA
Registered: Feb 2002


 - posted 02-08-2004 03:51 AM      Profile for Brad Morris   Email Brad Morris   Send New Private Message       Edit/Delete Post 
Time to ask the pros.....

For those booths that run mag film, how often do you degauss the path and parts that come in contact with the film? What type of degausser do you use?

Thanks.

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Floyd Justin Newton
Jedi Master Film Handler

Posts: 559
From: Phoenix, Arizona, USA
Registered: Jun 2002


 - posted 02-08-2004 09:19 AM      Profile for Floyd Justin Newton   Email Floyd Justin Newton   Send New Private Message       Edit/Delete Post 
Brad--

I have found that degausing the ENTIRE film path with complete
thourghness is the best insurance in elemination of track "HISS"
and noise which CANNOT be removed once it is there. It would
take a couple minutes per machine and has to be done slowly.

fjn [Smile]

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999


 - posted 02-08-2004 09:21 AM      Profile for John Walsh   Email John Walsh   Send New Private Message       Edit/Delete Post 
We would carefully check and degauss for every print we ran; would check it every 2-3 weeks. It's been a long time I ran mag [Frown] but if I remember, I think you want a meter that reads 0 to 1 gauss. Of course, you want it to be as low as possible, but definitely less than 1.

To check, we used meters from:
http://www.rbannis.com/index.jsp

I only see one model (25); they used to make a smaller one which was easier to get into the shrouded area of most mag heads. Another manufacturer may still make smaller models. It also has a sort of 'extension' probe; it was a flat piece of spring steel the clipped to the bottom. They also make demag tools; 'buzzers' as we called them.

Once you have demaged the head, don't forget to do any screwdrivers or other tools you use to work on the projector.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99


 - posted 02-08-2004 09:29 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
There is a hand neld device called the Annis Magnetomiter that looks similar to a compass that can read the existance any magnitism in the film path. Its VERY sensitive capable of reading a maximum of plus or minus 5 gauss but ther eis one available as sensitive as .5 gauss! Its the only inexpensive, less than 100.00, device I know of that can verify the existance of magnetism or not. I also have one of their Han-D-Mags as well.
Their web site is here.....
http://www.rbannis.com
Mark @ CLACO

Looks like John and I were on the same page at the same time [thumbsup]

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 02-08-2004 09:37 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
I use the guass meter daily and also ensure all your tools (screw drivers and allen wrenchs are degaussed as well also splicer and rewind spindles
Also if you use a platter all the roller spindles payout modules and even the screws that hold the platter decks on at one point a certain manufacturer used a magnetic screw gun to put in all there deck screws and every print on them got a tick tick tick added to the track

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Mike Carro
Film Handler

Posts: 67
From: Tempe, Az USA
Registered: Nov 1999


 - posted 02-10-2004 10:06 AM      Profile for Mike Carro   Author's Homepage   Email Mike Carro   Send New Private Message       Edit/Delete Post 
I run 70mm. where do I get a Gauss meter?

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 02-10-2004 10:32 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
read the posts above as the link to the source is there [Smile]

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Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003


 - posted 02-10-2004 10:41 AM      Profile for Sam D. Chavez   Author's Homepage     Send New Private Message       Edit/Delete Post 
RB Annis is the place. There used to be a Mr. Annis. Hopefully he is still around. I used to give the meters away at the Dolby training courses.

There are myriad ways to put clicks on the soundtrack or even erase it.

The original Christie cue detector used a magnetized pickup and relied on ferrous metal cues to trigger. I once ran a wonderful mag print of Dr. Zhivago that was moved over from the "good" house, and over my prostests, on one of these systems and as a test later took a reel back to the good house where the fader that used to run at 8 of 20 was now at 18 to get any sound at all.

Speco used to use magnets to hold the tail on the platter. When I pointed this out to one of the owners at a Showest years ago, he blew cigar smoke in my face.

I saw a tech work on the feed valve of a Christie platter using a Tensor lamp on top of the film for illumination. The subsequent thumps were amazing.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 02-10-2004 10:50 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
"The subsequent thumps were amazing." I hope they had good subs [Big Grin]

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David Stambaugh
Film God

Posts: 4021
From: Eugene, Oregon
Registered: Jan 2002


 - posted 02-10-2004 11:38 AM      Profile for David Stambaugh   Author's Homepage   Email David Stambaugh   Send New Private Message       Edit/Delete Post 
One of the 70mm mag shows of "ET" that I saw was marred by a loud "tick - tick - tick" in the sound for about the first 15 minutes. Sure sounded like something magnetic came in contact with the print.

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Brad Morris
Film Handler

Posts: 29
From: Los Angeles, CA, USA
Registered: Feb 2002


 - posted 02-11-2004 11:55 PM      Profile for Brad Morris   Email Brad Morris   Send New Private Message       Edit/Delete Post 
Thanks to all for the help. Now I just have to remember to take my watch off when using the degausser!

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System Notices
Forum Watchdog / Soup Nazi

Posts: 215

Registered: Apr 2004


 - posted 12-12-2005 09:53 AM      Profile for System Notices         Edit/Delete Post 

It has been 669 days since the last post.


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Don Furr
Jedi Master Film Handler

Posts: 509
From: Sun City, Ca USA
Registered: Nov 2002


 - posted 12-12-2005 09:53 AM      Profile for Don Furr   Email Don Furr   Send New Private Message       Edit/Delete Post 
After having read all the replies in this thread and know where to get the gauge and the degaussing unit, but could some me a definite recommendation of exactly which degaussing model to purchase. I want one that I can wipe the entire film path through the projector without removing items and running them through a circular magnetic field. Also what about the head clusters themselves. Do you degauss the heads as well? If anyone is aware of a tutorial on the web explaining "how to do it" please let me know.

Don

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Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003


 - posted 12-12-2005 10:15 AM      Profile for Sam D. Chavez   Author's Homepage     Send New Private Message       Edit/Delete Post 
I do not have a specific model to tout.

The heads should always be degaussed (with the sound system off)particularly pre Teccon heads where the metal is very permeable.

If you a running platters, the screws that attach the decks to the frame are notorious for putting clicks on the film

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Jim Latendorf
Film Handler

Posts: 4
From: Sacramento, CA, USA
Registered: Oct 2005


 - posted 12-12-2005 11:33 AM      Profile for Jim Latendorf   Email Jim Latendorf   Send New Private Message       Edit/Delete Post 
"One of the 70mm mag shows of "ET" that I saw was marred by a loud "tick - tick - tick" in the sound for about the first 15 minutes. Sure sounded like something magnetic came in contact with the print."

I have heard this "tick-tick" sound when playing reel to reel audio tapes. Caused by static discharge from the tape being picked up by the playback head. Doesn't harm the tape, though.

Jim L.

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