garage door opener electrical resistance

[haiyang]

I have a Genie 2027 garage door opener, and when measuring its power plug by a multimeter, it shows a resistance of ~6 ohm with connectivity. Is this normal? Is there a short circuit of some sort in there? The reason I began to measure is the wall outlet smoked up once when plugging the power cord in and I'm suspecting there's a short circuit somewhere.

Should a garage door opener show electrical resistance of only 6 ohm and connectivity all the time? I measured a radio and it shows a resistance of 71 ohm

Thanks!

 

[Bert_]

Does it work? If it does then it's normal.

 

[Bert_]

In all seriousness you are just measuring the DC resistance of the control transformer. The inductance (AC resistance) is much higher but your meter doesn't measure that.

 

[Innovate1]

Could be the resistance of a transformer although many use switching power supplies now so a multimeter may should open due to the low voltage it puts on the circuit.

I am wondering just what "smoked up once" means. If the plug is slowly inserted and there is a sustained arc in the receptacle that might cause some smoke.

Does the unit work? If so I think Bert is on the right track. You could measure the ac current if you have a meter that can measure it.

One thing you can do if you suspect a short circuit is connect an incandescent light bulb in series with the opener. If the motor isn't running the bulb should be pretty dim.

 

[haiyang]

The garage door opener does work but when I plugged in a light on the same wall outlet, it blow up the bulb and there was a lighting arc coming out and blacked the wall outlet plastic cover. That was why I thought there was a short circuit there - but it could be a temporary surge, and I don't know how to test the difference

 

[Bert_]

Sounds like you should be looking at the outlet.

 

[Innovate1]

The garage door opener does work but when I plugged in a light on the same wall outlet, it blow up the bulb and there was a lighting arc coming out and blacked the wall outlet plastic cover. That was why I thought there was a short circuit there - but it could be a temporary surge, and I don't know how to test the difference

I would check the voltages at the outlet (each pin to every other pin) and make sure all the connections are correct. Then figure out why the light blew up. If the opener works and the light blew up why are you looking at the opener? The problem may be the light. Maybe there was a loose strand of wire on the plug that got vaporized when you plugged it in.