[Tig] Low Frequency EMI - 60Hz

Wilf Giovanella wgiovanella
Sat May 24 20:18:40 BST 2003

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 
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

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