Something wierd happen me today, A couple weeks ago i had a AL-12 alarm so i dismanteld the spindle servo i measured a bad transistor so today i got my spare parts, so i mounted the new one and started up the lathe, i worked fine. Tested the spindle with 300,500,2000 rpm and i worked fine, So i made a final free spinn test 4000rpm(max), it accelerated up and "boom" the lights i my workshop stared to blink... And then one main fuse for the lathe blew.. so it limped for 2 sec and stopped and i turned it off... I replaced the main fuse and started it up again.. All ok until the spindle servo turns on.. the light starts blink... And i tested to start the spindle and "boom" again.. the F7 fuse blew up(dc link) and again a AL-12 alarm..

I shall dismantel it again towmorrow.. i saw that a little diod or some thing was burned... A little component with 2legs a "ball 5mm diam." body with a red stripe on one side.. Mounted between the output on the transistor bridge... any one know what it is??


An why started the lights to blink... i have a tranformator before the lathe.. So is it a short in the driver, and the trafo prevent it from being a "real" shortcut??

Its a Digital AC Spindle drive, model 12

//Johan Marquardt