> > It's a well-known fault, but has anyone ever known one fail and actually > cause any damage (other than to itself)? AIUI, they're there to reduce
Not really. Maybe a blown fuse. I have had the live-earth capacitor in a filter fail and trip the RCD in my consumer unit (meaning I was in the dark until I reset t). Does damage to my nerves count :-) If one of these capacitors in a mains filter circuit fails I tend to replace the lot (for all I don't like shotgun debugging). If I was repairing something for somebody else then I'd probably change them [1]). I might change them if I was rebulding the PSU section of a machine I own. Otherwise I just leave them until the fail. [1] Otherwise when they fail a few weeks/months/years later I might find I have to replace them for free. Incidentally, some machines have those sealed metal cans containing filter capacitors, inductors and sometimes discharge resistors [2]. Has anyone ever had the capacitors in one of those fail? [2] I wish the manufacturers would print a schematic on the can, or at least in an available data sheet. If I measure a 1M leak to earth from the live pin (say), I want to know if it's a deliberate discharging resistor or a leaking capacitor. -tony
