Lightning/Garage Door Opener Inoperative



Question:
My 12 year old Stanley T-120 garage door opener has stopped working after a recent lightning storm. The unit makes no movement or noise when using the remote, push button, or keypad. The storm also blew several fuses, two receptacles, and shorted the wiring in the circuit where the opener plugs into the wall outlet, all of which I have fixed.(there are some metal shelves along the wall that the wiring runs through, and the surge blew a small hole in the wall to get to them) The cord from the wall outlet to the opener tests okay. The insurance deductable is $250, so it would be cheaper to get a new opener. I have intermediate electronics ability, and would appreciate it someone could identify the most likely problem area(s) to start.

Answer:
www.repairfaq.org can be helpful, and I believe it has information specific to lightning repairs. As long as the CPU (probably 24-28 pin chip) or the radio decoder chip didn't blow, you can fix it for a lot less than the cost of a new opener because all the other parts are generic, and you should be able to track down the bad ones by doing voltage and ohmmeter tests. Start where the 120VAC connects to the circuit board and measure for 120VAC, then measure the low voltages at the secondary side of the transformer, rectifier, filter capacitors, regulator (probably one for about 5-8 volts and another for the 12V relays). If you find any bad relay driver transistors, replace their protective diodes as well, to prevent back-EMF damage to the new transistors. The radio portion of the circuit board is near the antenna and coil, and the decoder chip should be there as well. The output of this chip probably leads to the logic portion of the circuit board, specifically the part that handles the wall pushbutton. Look for a signal that goes active when you press the remote button. If the opener is old enough to not have a CPU, it probably uses some 4000-series CMOS chips, all generic, all cheap, and the radio decoder chip is a National Semi. part identical to the one in the remote. If you get the opener to work again, be sure to replace the MOVs that provide surge protection with new ones rated for 130-150 volts ACrms (not peak). Stanleys should have 3 of them (hot-neutral, hot-ground, neutral-ground), unlike the inferior Chamberlains (Sears, Liftmaster).





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