Q400 is the one that sits right next to the IC, make sure it's not bad,
which is possible. If it's good then I think your regulator STR30130 is
bad. A burnt 1k resistor to pin 2 should turn off the IC, so if it's
still putting voltage out on pin 4 it's bad it looks like from my
perspective. The way it works is the input voltage (pin 3) stays a
constant aprox 150-160vdc regardless of whether the set is on or off.
Pin 2 is your on/off control, it sits around 15v when set is off along
with the output on pin 4. When pin 2 is turned high when the set is
turned on, pin 4 follows and outputs your 130v supply.