Garage door opener sensors not working.


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Old 03-03-21, 10:50 AM
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Garage door opener sensors not working.

I have a Craftsman 1/2 HP model 139.53910 garage door opener with safety sensors that are not working. A litter of kittens broke the wires from the receiving sensor, and the sender had lost a lens so I got a new set of sensors. Wired them in correctly (White to White, Black stripe, to Black stripe) but they still do not work. The status leds on the sensors do not light on either sensor. However, when I hold the inside door bell switch closed, the door will come down. So, I assume that there is a break or short in the sensor wires some where.

The diagnostic led on the door opener unit is giving a two (2) flash signal that indicates "Safety sensors wire shorted or black/white wire reversed." I took great care NOT to reverse the wires so I assume that I have either a broken wire(s), or a fault on the circuit board itself.

There are three terminals on the opener. The inside garage door bell switch is wired to numbers one and two as indicated in the attached graphic. Number two terminal is connected to both white wires from the sensors, number three terminal has the black striped wires from both sensors.

To test to see if the break is in the wires (not the circuit board), I intend on putting a jumper wire between terminals two and three and then jump one and two (or just get down from the ladder and press the inside garage switch). My reasoning is that those jumpers should enable closing of the door if the fault is in the wires. If it does not work, then the problem would be in the circuit board itself. Or is my thinking wrong...I don't want to screw things up.

Craftsman 139.53910 garage door opener terminals.
 

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03-04-21, 10:36 AM
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I can't speak to your will it work or won't it (your including parts other than the wires so....). Do you have an aversion to buying a cheap but useful continuity tester ($6-$7 at HF) and not monkeying around with a workaround? You could even do it with just some wire/battery/light bulb.

By not reading the post, you have wasted my time and yours.
Btw, this kind of snarkyness in my experience really puts a damper on anyone helping out.
 
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Old 03-03-21, 03:55 PM
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The status leds on the sensors do not light on either sensor.
Didn't have to read the rest of the post, if the sensor lights are not lit then something is not wired correctly or you have an open circuit.

Forget any jumpers till you sort out the wiring, maybe put in all new wiring to get them powered up!
 
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Old 03-04-21, 10:22 AM
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By not reading the entire post, you missed the point.
 
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Old 03-04-21, 10:25 AM
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By not reading the post, you have wasted my time and yours. The purpose of using jumpers is to find if the problem is in the circuit board or the wires...I do not want to waste time "fixing" the wires if the fault is in the cuircut board itself.

"To test to see if the break is in the wires (not the circuit board),..."
 
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Old 03-04-21, 10:36 AM
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I can't speak to your will it work or won't it (your including parts other than the wires so....). Do you have an aversion to buying a cheap but useful continuity tester ($6-$7 at HF) and not monkeying around with a workaround? You could even do it with just some wire/battery/light bulb.

By not reading the post, you have wasted my time and yours.
Btw, this kind of snarkyness in my experience really puts a damper on anyone helping out.
 
Marq1, Norm201 voted this post useful.
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Old 03-04-21, 11:51 AM
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The purpose of using jumpers is to find if the problem is in the circuit board or the wires
So lets look at it logically, what are you going to address first, the $5 cost for new wire, or the $XX circuit board?

And, if it's not the wire then you might want to consider that the cost of the board is probably up there close to the cost of a new opener!
 
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Old 03-04-21, 01:25 PM
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The diagnostic led on the door opener unit is giving a two (2) flash signal that indicates "Safety sensors wire shorted or black/white wire reversed." I took great care NOT to reverse the wires so I assume that I have either a broken wire(s), or a fault on the circuit board itself.
I think this tells all. You assumed the simplest of all things by not checking the actual wire. And the fact that your cat did the damage tells me, the wire is the most likely problem.
If the fault lies in the CB then most likely the door would not work at all or very intermittently.
 
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Old 03-10-21, 07:44 AM
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Sensors not working, Addendum.

I replaced the sensor, replaced the wires. The door still will not close without hold the wall button down. The status lights on the sensors are still not lighted up. All connections correct, no wires reversed, no wires pinched by the staples etc.

I will also add that there were periods of time last Spring and Summer when the door would work correctly, times when it would not. This led to to believe that the fault was possibly the circuit board itself.

With the new wiring and sensors, I still get the auto stop when I push the internal wall-mounted button, and must let off and then hold it on to get the door to close. After closing, the two flash signal is observed.

In sum I have ruled-out wires and sensors as being the source of the problem.

Any thoughts?
 
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Old 03-10-21, 07:50 AM
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I can't speak to your will it work or won't it (your including parts other than the wires so....). Do you have an aversion to buying a cheap but useful continuity tester ($6-$7 at HF) and not monkeying around with a workaround? You could even do it with just some wire/battery/light bulb.
The new wires are already installed. I have a couple of inexpensive continuity testers. However, the continuity tester lead is only about three feet long. How do I test the continuity of wires where the ends are 25 feet apart?
 
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Old 03-10-21, 08:29 AM
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On one end of the 25' twist the wires together. Test that they make a circuit at the other end. If so then you know both wires are good. If no circuit, then one is bad and it doesn't matter which one as the line will need to be replaced.

If you're curious which wire is bad, you'll need 20' of spare wire to extend one end back to the other. Probably cost you a couple bucks.
 
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Old 03-10-21, 06:50 PM
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You cannot use a jumper across terminals 2 and 3. That would still show a short to the board.
Also the sensors generate a pulse that is needed to satisfy the safety circuit.

I'm pretty sure you need to use Chamberlain replacement sensors.
Chamberlain 041A503 safety sensor kit
 
 

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