My husqvarna sewing machine has started sewing by itself when I plug it in and turn it on. I can't stop it sewing by itself. How do I stop this I've checked all buttons and plugs

Hi all. I inherited a 6440 with this issue. The problem is a blown capacitor. The simple, but not entirely "right" solution is to remove it. If you take off the motor case housing you will see the motor/foot pedal wiring area to the right of the motor (facing from the rear of the machine). There are 4 screws holding wires and the capacitor. The lower two screws hold the capacitor which is brownish-silver in color. Just back off the screws and pull it out; tighten the screws after removing. Mine was ruptured and I've seen the same image here: http://jim-linda.blogspot.com/2011/08/viking-husqvarna-model-6440-sewing.html Again, removing this capacitor solves the issue, but to fix it "right" go to RadioShack and get a .1uF/250V capacitor and install it the same way you removed the old one. The RadioShack part # is 272-1053. It's online listing is here: http://www.radioshack.com/product/index.jsp?productId=2102589

Does the foot pedal plug into the machine by itself? if so unplug the foot pedal & then turn on the machine, if it doesn't run by it's self then you know it's the foot pedal.
but if it still has the problem check the foot pedal for a circuit board

My Viking Husqvarna 6440 has also developed this problem. Cannot stop it running except by pulling the plug. Sorry I cannot offer a solution.

What model is your machine? If it is a computerized model with a Start/Stop button, I would check to be sure that button is not permanently depressed. The next thing I would do is check the food pedal - it may be stuck in a position that makes it run straight away when the power is turned on (maybe a small bit of "stuff" is stuck down the side between the pedal and the part that sits on the floor???).

I think also that some of the upper end machines might have settings for disabled persons and maybe yours has this facility turned on?