Craftsman 1/2 HP Garage Door Opener Problem
I have a Sears Craftsman 1/2 HP Garage Door Opener that is about 4.5 years old. Model number is 139.53xxxSRT1. Recently it has started to not close without the safety overide, that is, by pushing and keeping down the Wall Premium Console Control (3 button one) close button till the garage door closes completely.
The receiver sensor's green light was not staying on, so I tried aligning it many many times and never got it to stay on continuously. I even ordered new sensors from Sears and wired those up and same problem. The green light on the sensor would no stay on.
After lot of trying this is what I see, when I bring the recieving sensor to within 4 feet of the sending sensor then the green light stays on and the door closes. As I take the receiving sensor farther than 4 feet the green led will stay on for 1 to 2 seconds and then fade away and door will not close. I hooked the same sensors to the 2nd exact garage door opener I have and the reciever's green light stays light. I also checked the voltage at the two screws where the sensor wires are hooked to and the garage door opener that will not close shows about 4 volts and the other good garage door opener shows abot 6 volts. Other than not being able to close the door with the remote and having to manually overide the safety sensors, everything works good.
I am looking for help on how to fix this problem, as cheaply as possible of course :-). Is there any thing I can do on the board to increase the voltage to the sensors? Or is there some thing else I am not doing correctly? Any help will be appreciated.