Plasmas really are a pain. Generally, if you put plasma tv's in the auto-gen mode, and you get the scrolling colours, does that eliminate the control pcb. I have one on the bench that takes up to 10 minutes to come on from cold but if you bridge the "auto gen" the screen emits colours. Rumour has it the 3.6 regulator on the signal pcb causes similar symptoms but this is ok, cheers.