I have the above speed controller and would like to test if it is functioning the way it should but don't know how to go about it. The Dremel without any doubt overheated in use. After switching it off and resting it for a while, it just would not switch on again. I have also checked the switch which is fine.

I have attached a few photos hoping it will help. Could somebody please tell me how to go about this. I have a decent Fluke meter. The voltage in is 240Vac (UK). The 2 screws are where the 240vac is input. Right hand screw is positive. I checked the diodes on the back of the board and they all seem to be OK. (About 0.7v)

I would really appreciate some ideas on this. Thanks a lot folks.........Take care, stay safe.

 

I don't see anything like it in the photographs, but I would check for a thermal fuse (may be inside the motor) or some other type of fuse.

 

I don't see anything like it in the photographs, but I would check for a thermal fuse (may be inside the motor) or some other type of fuse.

There is a thermal fuse which is attached to a brush holder which plugs into the field coil. I tested the thermal fuse and do get continuity so I take it its OK.

 

Agreed, the thermal fuse is probably ok.