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Another Liftmaster (Craftsman) Problem

Posted by larrylwill (My Page) on
Sun, Oct 14, 07 at 22:31

I just bought a house that had a working GDO. Three months after we closed and returned to the house I found out that lighting had hit nearby and killed the neighbors computer and automatic gate opener. When I tried to open the GD it didnt work. I determaned that the main board was blown, several diodes and the regulator were shorted. I ordered a new main board.
Now the motor works with the remote and button but the door will not close. It goes about 6" and returns.
Here is what is different from what I have read elsewhere in the fourm. If I hold the button it will NOT close, it just goes 6" and returns.
I checked the sensors and both leds were out. I disconnected them and hooked up the transmitter only. The Led comes on bright green but when I connect the receiver it goes out.
The main circuit board is supplying about 6vdc to the sensors. I assume that they are connected in parallel across terminal 2 and 3 and the main button from 1 to 2 ?
Im guessing that the receiver is blown although I cant find a problem on the board.
However I am getting 5 flashes of the green led on the main board which I think signifies a bad shutter counter. I do not want to buy a set of sensors and find out that I also need the shutter board. I already have $80 in this.

In your opinion could this just be the sensor?

Is there a way to simulate good sensors to make sure everything else works?

thank you

Follow-Up Postings:

RE: Another Liftmaster (Craftsman) Problem

Everything points to multiple problems. The problem with the sensors and the LEDs going out sounds like a short in the wiring. The problem with the door not closing and the code you are getting point to the RPM board (shutter). I would tackle the sensors first because you can substitute in some wire to eliminate the possibility of a short. You must follow the color coding on the wire. The RPM board can't be too expensive.

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