A led light bulb (230V~) went dark in a room. By dark I mean that it dimmed down to very low light. No, I do not have a dimmer nor is it a light bulb with some fancy build-in iot stuff.

Two classic halogen bulbs didn't work in that socket. Testing the led bulb in a different socket it worked. I looked for contact problems and cleaned the contacts and the lamp seemed to work again using the led light bulb.

Then it went dark again and I decided to exchange the socket in the lamp. Opening the socket I found that in-between one of the cables and the socket an electronic part had been placed by soldering it to the end of the power line and fastening it to the socket.

I took out that part having never seen a stupid simple lamp coming with some small electric part build in. The lamp worked again with the all the bulbs I had tried.

Looking at for the specs I found this datasheet. It seems to be a resettable fuse or polymeric positive temperature coefficient device. I didn't know about these, but obviously the one I took out of the circuit seemed to have broken in a way that it switches too fast to a high resistance that only allows the led light bulb to glow dimly and isn't sufficient to drive a classic light bulb.

I guess the pptc has been put into the plastic lamp to protect it from heat: If a certain amount of power would be exceeded the light bulb used probably would emit too much heat for the lamp case. Still the lamp came with the usual label saying what light sources are allowed, but not stating any hint that it would not work with non-spec light sources or would contain active electronic parts.