RCA Projection picture is flashing on/off quickly

I have a RCA P46920BL  chasis: PTK195KA, and the picture and sound is quickly flashing on and off.  I believe it is turning the tv itself on and off very rapidly.  I have changed the convergence IC stk730-130 4 or 5 months ago and it has been working great since.  Does anybody know what the cause is? Thanks