Tonight I was running the burn in on my PDP-5020FD and the screen was dark blue. The set is roughly 30 feet from the kitchen and I went to go get something to drink and turned on the kitchen light and the PDP-5020FD started buzzing like a bee so I tuned the light off and the buzzing stopped.
After careful thought it finally makes sense, I have florescent lights and they have what is called a ballast, when the ballast is energized it sends of RF (radio frequency waves) which are transmitted through the air and are attracted to the power lines of the audio and video components. They then "ride" the line in and cause problems with PCB's
I am currently trying to find a cheap fix for this!