On January 13, 2012 at 13:50, tweeterguy said...
The OP referred to a 9 way 3.5 mm in post nine, likely incorrect terminology or missing some words in his sentence, i.e. 9 pin DB9 to 3.5mm I assume.
My money is on this alone not solving his problem with the 'noise'. One of the systems we had this problem with was IR only and the other did it while serial connections were taken out.
did you use IR on ports 7-12? did you use sleeved emitters?