Hi Joe, On Tue, Apr 23, 2013 at 4:28 AM, IVP wrote: > Hi all, > > my grinder (a hand-held Bosch) suddenly stopped the other day > > I assumed it was probably a broken wire in the mains cable and > so took it apart to repair it > > The cable was fine but a 0.22uF X2 capacitor across P and N > had detached. Both legs had come out of the capacitor body. I > can't really tell whether it was arcing or just general corrosion > > It was physically quite small and the only one I had which would fit > the space was a 0.1uf X2 > > The grinder does run now but sometimes needs a flick of the wheel > to get it started, or runs slowly, runs jerkily or at full speed but slow= s > under load > > I'm looking for a 0.22uF X2 to fit but I'm just curious as to the > purpose of this capacitor and the effect of its value on operation The capacitor sounds like it's a filter capacitor to prevent spikes from going back to the mains, from what I can think. In most cases, if you have a brushed motor and the motor runs with a low torque, the carbon brushes are to be blamed in almost all cases. (wear and tear of the brushes; worn out after long periods usage, or worn out faster when run continuously hot for a long period of time) You can buy spare brushes from a store and replace them, or as a temporary measure remove the brushes, clean them and the commutator contacts with spirit free of the dislodged carbon. It is quite unlikely, that you have an induction motor for that use case, from what I can imagine. Regards, Manu --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .