This is a small board (56+60 mm), whose origin I do not recall.
It seems a sort of noise filter: the main capacitors are as per EN132400, which seems to be a standard for capacitors in line filtering applications, so that the amount of radio/electromagnetic interferences generated by the equipment, and transmitted back to the supply line, is minimized. Two sources of information on this subjec: one and two.
Two pictures of the board:
It shows a mark: "KX 1011-553".
(The switch seems to be broken: it is closed at all times).
A snapshot of the schematics:
Mmmm ... I do not know how does this work:
- The main noise filtering capacitors seem to be placed following a X (C1) and Y (C2) arrangements.
- I have simulated the bobine as a transformer, but with a weird layout of primary and secondary.
- As I see it, both LEDS should be on.
- I cannot test it because my oscilloscope is max 30 V.