Hello All,

I am dealing with a bunch of relays that have burnt out contacts: Mechanics
works fine but contacts measure 3 - 15 Ohms between them instead of zero. I
opened several - the contact pads turned dark gray, almost black. It is not
coal, still looks like metal surface. The dark surface is very thin, several
passes of sandpaper clean it and relay works fine after that.

I wonder if there is a way to clean the contacts without opening relays (the
relays are sealed, the only way to open it to cut the body apart.)

Appreciate any wisdom

Andrey

PS: the relays are used to switch RF power at 2 - 30 MHz

a guess , jewellers use a device called a sonic cleaner.
It puts sonic waves into a cabinet and the shi,,, rubbish falls off. Don't
know about sealed relays, but if you want a clean ring get access to a
sonic.