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Topic: Hum/buzz when SH-1000 door is closed

David E. Nedrow
Master Film Handler

Posts: 368
From: Columbus, OH, USA
Registered: Oct 2008

posted 01-06-2012 07:50 PM

Sorry for the lag, but here's an update.

Adjusting the LED and pickup lens made no difference to the hum. So, another careful reading of the Simplex back-matter (Fields Notes). One suggestion was to connect a wire from ground on the sound processor to ground on the pickup assembly.

I alligator'd a wire between the two and that fixed the hum that started last month.

I'm installing conduit and new wiring for everything, so I'll take the time to separate high/low voltage lines, speaker wires, etc. I also want to get all of the grounds running to the panel. The current setup relies on the metal in some conduit as a common ground, but some of the wiring actually runs to another panel.

The other odd thing that happened at the same time the hum started, was that I now have ground loop noise in our video projection. You know what I mean, a very slowly rolling dark band moving up the screen, repeating ad-nauseum.

I still haven't tracked down what changed, but clearly something did.

I have some other questions re: the levels from the analog head, but I'll post that under separate cover.

-David

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Bruce Hansen
Jedi Master Film Handler

Posts: 847
From: Stone Mountain, GA, USA
Registered: Dec 1999

posted 01-06-2012 08:13 PM

The "bars" rolling through your video are hum. Has someone been doing electrilcal work ar your place, or has some new equipment, that draws a good amount of current been pluged in? It almost sounds like a ground and a neutral have been connected together somewhere - that would cause hum all over the place, or one leg of your power has been loaded more than the others, that imbalance will also cause hum.

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