Philips Psu Keeps Blowing Fuse ?

[mzone]

we have a philips 50pf9966 set powers up ok however shows no picture.

have found that it keeps blowing one of the t4ah/250v ceramic fuse on power supply, i changed fuse and used a glass 4amp quick blow fuse as thats all i had avalible. re-tryed tv on on the variac on low voltage but i keeps blowing fuse.

board number lj44-00065a

any ideas of possible faults?

thanks