Hey everyone,
I'm working on simulating a circuit in KiCad to better understand how it functions. There's one component I'm having trouble identifying
it's highlighted in red in the attached photo.
Using the multimeter, I get around 4.5 MΩ when the black probe is on the banded side and the red probe on the other side, and (OL) in reverse.
I'm not sure if it's a resistor, thermistor, varistor, or something else entirely. If anyone recognizes it or has any insight, I'd really appreciate your help.
Thanks in advance!

 

 

Post another photo with a different camera and lighting angle so that we can clearly read the marking on the square black chip.
It looks like 590B visible.

Also it helps if you told us what device/appliance this came from.

 

Post another photo with a different camera and lighting angle so that we can clearly read the marking on the square black chip.
It looks like 590B visible.

Also it helps if you told us what device/appliance this came from.

This comes from the PILZ PNOZ X4 safety relay, the chip is the 690B optocoupler.
Here is another picture of the relevant part:

 

spook nailed it. Rectifiers.

https://www.vishay.com/docs/88546/bym10-xxx.pdf