Film-Tech Forum ARCHIVE: Causing an audio “crackle”& damaging prints...HELP!

This is topic Causing an audio “crackle”& damaging prints...HELP! in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011603

Posted by Robert E. Allen (Member # 1351) on 02-09-2014, 02:31 PM:

Hey Guys,

My name is Tim and I've registered for the forum but I'm not approved yet so I am using my Father's account to YELL for help.

My Folks and I have a 35mm setup that is damaging the audio track in some way that is causing a “crackle” to be evident after just a few runs. My Father is not a tech and has not been able to tell me how we can fix it. After about 9 runs the audio is unbearable. We can't keep damaging prints...HELP!

Tim

I just checked the print and saw a series of light black horizontal scratches on the soundtrack side of the film and heard the "crackle" Tim is talking about. But I am at a loss to know what's scratching the film this way.

Bob

Posted by Brad Miller (Member # 2) on 02-09-2014, 03:30 PM:

I would look at the pad rollers first. Many projectors had pad rollers with flanges INSIDE the sprockets, meaning they would rub right onto the analog soundtrack if their clearance was too tight.

The general rule of thumb is 2 film thicknesses of clearance. I always set mine so with 2 pieces of film sandwiched in between the sprocket and pad roller let the pad rollers spin effortlessly, and with 3 thicknesses the pad rollers had a little bit of drag when they were spun by hand.

It would help knowing more of your system though. For example, projector head? Platter type? Are you running soundtrack up or down on the platter? Etc. Also are the soundtrack scratches on the emulsion or base side of the film?

Posted by Louis Bornwasser (Member # 3063) on 02-09-2014, 07:16 PM:

Amplifying Brad: There is not much that touches the soundtrack area, emulsion side.

Horizontl scratches may project on the screen if the aperture is removed and the flat lens used.

Although I am leaning toward the platter, what kind of projector and soundhead?

Louis

Posted by Robert E. Allen (Member # 1351) on 02-10-2014, 01:22 PM:

Thanks Brad. I'll check it out.

Louis: Simplex 35 sound and picture.

Bob

Posted by Gordon McLeod (Member # 33) on 02-10-2014, 01:32 PM:

If it is a 5 star soundhead often that stupid metal plate that the padroller arm is mounted on gets out of adjustment so badly that not only if the roller riding onto the film but I have seen it damage the perfs as well so the film will not wind evenly on the plater