[Tig] Low Frequency EMI - 60Hz

Jan & Eileen wb9iph
Sat May 24 21:43:36 BST 2003


XYZ controls, if I'm correct (in earlier Davinci's & 888) were being
activated at video rate, not film rate.... and that can be interpreted 
As horizontal jitter..
[Watch me get jumped now!!! :)]


-----Original Message-----
From: tig-admin at tig.colorist.org [mailto:tig-admin at tig.colorist.org] On
Behalf Of Wilf Giovanella
Sent: Saturday, May 24, 2003 2:19 PM
To: Alex Pimentel; tig at tig.colorist.org
Subject: Re: [Tig] Low Frequency EMI - 60Hz

Jeff Heusser supports the tig.

I have seen positional hum introduced into daVinci analog XYZ controls in a
Cintel 
machine.  It shows up as a horizontal jitter. (like the jump scan days).  I
found that 
excess control cable was coiled in the bottom of a rack.  Mu-Metal solved
the 
problem until the cable cut shorter and not coiled.
I have also seen image shift as much as 5% and a purity shift caused by
street car 
power lines.  In this case it was induced into the monitors and TK scanning.
No 
amount of shielding was able to eliminate the problem. The equipment was at
least 
75 feet from the source.  Street cars use DC.  Normally DC surges are not as

dramatic, and the supply lines are together and the EMI from the + and -
will cancel 
out.
With street cars and electric trollies one line overhead, the other is the
rail. The 
current is always surging and due to the distances between the EM  sources,
they will 
pull and push the electron beam around the screen.

Wilf Giovanella
Deluxe | Sound and Picture
Toronto


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