Sears Garage Door Opener problem, and questions

I have an older , Sears, chain operated garage door opener. Mechanically, the door is working fine, but I have a problem with the two safety sensors that beam a light across the bottom edge of the door, about 5 inches off the floor bottom.
The door will open fine, but will not close. I am 99% sure the problem is in the two sensors just described.
On one of the sensors, which I think is the sending unit, the little pilot led light is bright and pretty. However, on the other unit, which is marked the "Receptor" unit, the small led light is barely, barely, lit. It is getting voltage, as the led pilot light will very faintly light up when I apply the electrical wiring plug into it. I can also tell that when I line up the two sensors, and then place my hand across the beam of light, I can just barely detect that it faintly changes the intensity of the led pilot light.
My suspicion is that this "Receptor" unit has gone bad.
Two Questions please:
1. Am I on the right track ?
2. Can these sensors be bought at Lowe's or Home Depot ?
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Any comments or input would be very much appreciated.
Thank you very much !!
James
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...
Possibly...take them and place directly in front of each other a foot or so apart and test -- if works reliably, pretty good clue. Of course, make sure the lenses are clean on both. Also can test by jumpering the input to close the circuit to test.

... I'm sure somewhere they can be obtained; whether at the BORG's I don't know; all my openers are old enough they predate the infrared sensors so never had any need for replacements...
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Ok, I shorted the wires going to the Receptor Sensor, and when I do that, the small led light on the Sending unit goes out, but the door will still not go down. The only way that I can make it go down is to press **and hold** the manual switch inside the garage itself. I assume that by doing this, I am in effect, manually by-passing the safety feature...........
It will go up fine.
Any other ideas ??
James
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As noted, never had one w/ the light interlock to have had the opportunity to fiddle w/ it, but would seem that would be wrong set of leads to short -- I'd think there would be a completed circuit via the emitter/sender unit from one to the other. The inputs at the unit from the interlock would be where I'd do my jumpering...again, this is surmising w/o direct experience.
Did you try the lens-cleaning and the direct-coupling alignment/ sensitivity experiment(s) suggested?
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dpb:
Did you try the lens-cleaning and the direct-coupling alignment/ sensitivity experiment(s) suggested?
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I am going to do this experiment tomorrow. Thanks !!
G. Morgan, you link to the Amazon site is great !! If it looks like I need the sensors, that will be my ready source !!
Thanks to both of you !!
James
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James wrote:

If the beams are properly aligned, and the wiring is not cut, then you need to replace the beams. I just did that on my dad's opener last week.
It is a safety measure "fail safe", so the door will only go up by itself -as not to crush something in the opening because the safety device is malfunctioning.
I got a set for $29. Here is where you can order them, make sure you get the right ones for your opener.
(Amazon.com product link shortened)
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I\'ll be over here, looking through your stuff. -Jack Handey
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The lens on either unit might need cleaning. Sometimes sunlight during the evening or morning will hinder their operation.
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Ok, I did try the "free wheel" test, by releasing the latch and manually putting the door up and down. It goes up and down freely, with no binding etc
I tried to do the eye to eye matchup with the two sensors, but when I plug the receiver sensor in, the led on the transmitter goes out. This is not right........
if i just keep power to the transmitter, the led comes on.......... but when I power the receiveer, the transmitter light stays on, no matter where i aim the receiver.... there is just no pilot light on the sending unit........
from this, I am suspecting more and more that I have bad sensors.....
what you guys think ??
James
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in that last message, I typed one word wrong..........
here is the correct paragraph........
------------- if i just keep power to the transmitter, the led comes on.......... but when I power the receiver, the transmitter light stays OFF, no matter where i aim the receiver.... there is just no pilot light on the sending unit, as long as I have power to the receiver........
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