RF interference on DVD power cord

I have a stock power cord running from my Sony 7700s DVD player to my Bybee power conditioner (digital only). After much ado, I have definitely determined that this cord is the culprit for causing interference on my TV screen while playing DVD's. So, of course, I re-routed the cable trying intersect other cables at 90degrees. Voila'! A pristine picture! That is until the next time I watch a DVD a few days later. Interference again. I then re-route the power cord in a totally new path. Again, a great picture until a few days later. I'm getting tired of crawling behind my equipment rack. Any suggestions?
Four things could be happening here.

1) Your DVD player lacks proper filtering of the power supply, so digital RF based energy is using the power cord as an antenna to radiate a signal. Replacing the cord with a design that is if a low radiation / heavily shielded design may help. If you can't do that, the use of a snap together ferrite choke from Radio Shack may help quite a bit.

You would place this on the power cord as close to the DVD player as possible. Feed the power cord through the passage-way, loop it around the back-side of the ferrite and then through the ferrite passage-way again. Depending on the diameter of the power cord and the size of the passage-way in the ferrite, you might be able to wrap the cable around the other side of the ferrite and then back again through the opening. Either way, you want to make as many turns through the ferrite as you can, within reason. Two is better than one and three is better than two, but you don't want to strain the cable or have the ferrite digging into the cable jacket. Snap the ferrite closed and you're done.

This creates an impedance bump in the power cord, which makes the power cord a far less effective antenna for the RF radiation. Depending on the incoming AC in your area, it may even clean up your audio & video reproduction a bit.

2) You may have very poor connections somewhere in your AV system. Depending on how much you want to get into things, you can simply remove each cable from the existing socket and then re-seat it OR remove each cable, clean and treat each of the mating contact surfaces on both the cable and component and then re-seat each connection.

In many cases, simply pulling the cable out of the socket and re-seating it can make a very noticeable difference. Due to the differences in metalurgy and the pollutants in the air, connections tend to oxidize and corrode. By simply removing and replacing the cables back into their jacks, you break up the existing corrosion and form a new metal to metal bond.

Depending on the metals used and the quality of air in your dwelling, this connection may be good for anywhere between a few days to several months before this needs to be done again. JJ, who worked at Bell Labs and used to post over at AA had stated that he could measure distortion due to contact corrosion after appr 30 days of connection. Whether or not such distortion is audible or visible in your system is up to dispute. None the less, this is a simple step that one can take towards both improving and maintaining an existing connection or system.

3) Some of the cabling that you're using may either be be suffering from a poor connection at the jack and / or poor design that allows a high level of signal leakage in & out of the cabling itself. In either case, the interconnect or AV cable will act as an antenna, pulling in any stray EM or RF signals in the area. By using good quality cabling and checking to make sure that the cabling has good connections within their own RCA / BNC / XLR / F type jacks, much of this can be avoided.

4) Your power cords are too close to your signal cables, creating an inductive loop. This inductive loop allows signals to "jump" from cable to cable, resulting in distortion, crosstalk and higher noise floors. Separating the cables by just a small distance can sometimes make a very big difference, especially if you've got lower grade cabling and / or a bad connection in some of the cabling.

Hope this helps and gets you headed in the right direction. Sean
Try auditioning an aftermarket power cable. Most will offer greater insulation than the stock cable, which should help reject some of the interference.
The best deal on after market cords are these shielded Volex cords at about $1 a foot. Part numbers 17604 and 17605