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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Sprocket hole noise

Author Topic: Sprocket hole noise
Robert Throop
Master Film Handler

Posts: 412
From: Vernon, NY USA
Registered: Jun 99

 - posted 04-25-2006 06:51 PM      Profile for Robert Throop   Email Robert Throop   Send New Private Message       Edit/Delete Post 
I'm installing a CP50 and CE ASR40 readers in a changeover booth with Simplex SH 1007 soundheads. There are no problems with the #2 machine. #1 however has what seems to be sprocket hole noise. I've run buzz track with two straight lines on the scope. Cat. 97 shows no cross talk yet when I play program material there seems to be sprocket hole noise on the quiet sections. Any thoughts?

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Floyd Justin Newton
Jedi Master Film Handler

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

 - posted 04-25-2006 06:57 PM      Profile for Floyd Justin Newton   Email Floyd Justin Newton   Send New Private Message       Edit/Delete Post 

There is a lateral adjutment in your soundhead OR your slit
width may be a 'hair' too wide,

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12209
From: Annapolis, MD
Registered: Dec 1999

 - posted 04-25-2006 08:11 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Red reader or exciter lamp?

Do you have Dolby Digital basement readers?

If you have red readers, what you are most likely looking for is a reflection/scattering of the red light being modulated by the perforations, not necessarily a direct line. Using a business card you can often find where it is coming/reflecting from...sometimes off the chamfer of the drum.

If this is an exciter lamp system then th eproblem is most likely the pinch roller assembly. It is probably not hitting square on the G-1985 pinch roller. To verify, thread buzz track. Verify all are perfect. Then apply more pressure the the pinch roller in an even manner in the center of the bracket...if the buzz track does not change, all is good, if it does, the bracket has issues. Look for a crack in the barcket where the part that holds the roller and bearings joins to the part that has the pivot pin go through...the crack will be only in the upper bracket.

If you can take the film out and look at how the pinch roller hits the drum (use a flashlight from below and possibly a dental mirror to get a good view). The pinch roller has to hit the drum squarly and not favor either side.

Lastly, make sure the return spring on the lateral guide roller/pinch roller really is in charge of the film by having it push against the fixed roller.


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Louis Bornwasser
Film God

Posts: 4428
From: prospect ky usa
Registered: Mar 2005

 - posted 04-26-2006 03:28 PM      Profile for Louis Bornwasser   Author's Homepage   Email Louis Bornwasser   Send New Private Message       Edit/Delete Post 
Adding to Steve's post: If it is a reflection on a basement reader, disconnect the digital LED and the noise should go away. If this is the case, there is a "cover" available from Kelmar to stop the reflection. Louis

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Richard Fowler
Film God

Posts: 2389
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001

 - posted 04-26-2006 03:44 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
The CE ASR-40S reader has a press fitted lens tube to the chassis versus the more accurate threaded tube on the 30S series which may be a cause for the problem...this is after alinement, drifting parts on the Simplex head, poor release print, missing paint leaving bright bright spots of copper on the led mount, are considered....

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

 - posted 04-27-2006 10:04 AM      Profile for Darryl Spicer     Send New Private Message       Edit/Delete Post 
Don't forget that crazy dts timecode that is positioned in an area that test film would consider ok. I wonder why they don't just put a time code on the alighnment film to insure you don't pick it up.

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Robert Throop
Master Film Handler

Posts: 412
From: Vernon, NY USA
Registered: Jun 99

 - posted 04-30-2006 11:44 AM      Profile for Robert Throop   Email Robert Throop   Send New Private Message       Edit/Delete Post 
Thanks for all the replies. I think I finally fixed it although I'm not sure why. I tried moving the led around and I was not able to eliminate the noise. Yesterday I swapped leds between the two machines and voila! The noise is gone.

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