I came across a similar supply in a hi-tech refrigerator. The series resistor burnt when it was used with a modified sine wave inverter ( because i = C dv/dt) and I used the information in AN954 Transformerless rc psu to calculate the value. These supplies usually have a 1 watt or higher zener diode connected directly to the output of the bridge rectifier to limit the peak voltage.
Timescope
Timescope