I recently had a power surge, that fried several TV'S and appliances. I have tow garage door openers. 1 stopped working and the other didn’t but they were on 2 different circuits. I talked to 3 different liftmaster tech support people and all 3 said that it was the main circuit board. So I replaced it and still did not work. I got my voltmeter and had power coming in but none coming out. I ordered this transformer and installed it and everything worked fine. My original transformer was square and this one is round but they supply you with a new bracket to make installation very easy. This is a excellent quality part and shipping was very fast. I highly recommend this part
I hope this helps.