Schneider stv3680

[BBH]

Hey,

The signal too the base of q404 (2sd1554) is ok.
I have done a lamptest and checked the voltage on collector of q404. It was ok, 112Vdc.
But when I mount the q404 and turn on the set, I messure 450Vpp! on collector, instead of the 199Vpp wich is the correct voltage.

The set works fine with a normal picture for about 10min. After that tv goes into standby. And the Q404 is defecktive. After replacing Q404 it works for another 10min.

Anyone with some tips?