Frame Output I.C. has probably failed.
If it uses the TDA8175-S IC, (probably does) that's bad news, as Panasonic can no longer supply the original part and most of the major spares suppliers, have also run out of stock.
Panasonic now supply an awful modification repair kit as a replacement, (which as an engineer, I wouldn't touch with a barge pole). On the occasions I've repaired this fault I've tracked down smaller independant part suppliers and obtained the original part. Unfortunately, the TDA8175-S is now an extremely difficult part to obtain.
Estimate to repair..£70-£90
Cobweb, January 2005
