2, confirm that the pin 1 of the optocoupler (with a small dot on the foot of the breadboard also has the corresponding 1 feet of the logo) 1. Perform a test to confirm that the board being tested has been turned off and that the electrolytic capacitors on the motherboard are completely discharged. It is strictly conducting tests when the motherboard is energized. 3, the optocoupler breadboard connected to the USB power cable, the contact of the breadboard probe needs the optocoupler, if the optocoupler breadboard in the light has been flashing, it said the optocoupler is good (the brightness of the light may not be the same while it is flashing means the optocoupler is good) 4. Measurement to ensure that the test board of the optocoupler and the optocoupler measured good contact 5. If the indicator light is usually bright or not bright, the photocoupler can be removed from the circuit board and inserted into the photocoupler seat of the breadboard to reconfirm the test results., Weight: 0.0220462262 Pounds, Manufacturer: Faeymth