Title: 2x Universal K12 Air Conditioner Remote IR Receiver For Daikin Haier Gree Midea

In many cases, there are many types of infrared receivers worn by maintenance personnel, and it is not clear how the three pins are defined, which pin is GND, which is power +5v and which is signal pin.

The printing on some receiving boards is also vague.

In these situations, teach novices a practical trick.
First of all, most receiving boards will have small electrolytic capacitors such as 16v 47vf.
They are polarized.
The positive pole is connected to the +5v of the receiving head, and the negative pole is connected to the GND pin.

Again. After confirming the pins on the board, how can I confirm the pins of the receiving head that I am going to replace (if the model is the same, then the original model ca