The Upholstery Forum

I am having trouble with servo system on my juki lu563, after turning ON when I press paddle motor keeps running on low speed even I pickup my foot from paddle, I have tried to factory reset by holding N and it didn't work, even disconnecting needle sync sensor doesn't help , any idea

First thing is to verify nothing is sticking or binding.

Next, I would disconnect the linkage from the pedal and operate the lever by hand and see if it works properly then.

I did tried that , I opened the paddle controller and even by moving that magnetic liver inside the controller didn't stop the motor from running and I unplug the needle position synchronizer too but motor keep spinning in low rpm, it stops after 5 or 6 stitches when I turn off the system

Of course first look for mechanical things, sometimes the heel of the pedal could bottom out on the cross bar before returning to the full rest position. Sometimes the return spring is wimpy, solution is to stick a bit of scrap foam under the pedal to assist. Return spring has extra notches on the control lever, move it sway from the pivot if you haven't already. Needle positioner signal is a likely possibility. Unplug the needle positioner AND turn off needle positioning at the motor, button will cycle through needle up, down and off. Just unplugging it without telling the motor will definitely cause it to continue running as it tries to find the stop signal. If this solves it, start looking at the needle positioning controller itself. Making sure it is tightened to the handwheel and plug fully seated. Could just be faulty positioning sensor.

I tried everything you guys have suggested and even after trying resetting to factory setting motor was acting weird, but when open that paddle control switch and controlling internal black arm,motor start spinning but didn't want to stop. So by taking some readings with multimeter I found that small black color transistor looking sensor (actually its called as hall effect sensor) keep giving false voltage when I move back that black arm, so replace that sensor which fixed all my problem,
So i want to thank everyone who direct me diagnose that system