The transmitter and headphone in HT4186 set is LOCKED to each other, they should auto reconnect once both devices are powered on.
1. Power the transmitter with the giving USB cable connecting with any valid USB power source. You will see LED flashed BLUE.
2. Power on the headphone by pressing and holding the power button in the middle of "+"/"-" until LED turn BLUE.
3. Put them closer and wait for 5-10 sec, they will auto-connect. You will see SOLID BLUE light both on transmitter and headphone and hear "Your device is connected" from headphone.