i had exactly the same problem and was told it was the printed circuit board.after i had changed the pcb i still had the same problem(£140 later ouch) after further investigation i discovered it was the fan which appears to have been seizing up. back in with the fuse and everything was tickety boo. the fans are not cheap however nor is anything else for chaffs. engineers sometimes say its the pcb because when the fuse blows it leaves a black mark and is assumed "burntout". good luck
gaz
June 2009