Colleagues had asked about the converter earlier. I just got undressed at the workshop. Scheme does not really want to draw on me. The inverter is based on the FSCQ1565 system, properly according to the application note, with richer input and NTC filtering.
On the secondary side there is one winding with a double STPS20S100CT diode. There are two 2200? / 25V capacitors. There is no stabilizer and there is a voltage of 18V which supplies the heater section. It outputs 0, + 18V power supply (additionally filtered by a coil and capacitor), and one voltage to supply the controller in series with a 52? resistor which after charging gives about 16V.
The inverter also has heater control. The executive system is implemented on the mosfet N type transistor: STP60NF06FP. It is controlled by a optocoupler on the display board.