Sceadwian
Banned
Taking out the garbage today I happend across a junked speaker cabinet, it was trashed but I snagged the voice coils out of a decent woofer and tweeter to play with, it also had a crude crossover for the tweeter consisting of a 10u 50V capacitor and a 25ohm wirewound rheostat. Judging by the size I think it's rated for approximatly 25 watts.
I googled the markings on the rheostat but came up with zip,
They are
CM39771
25Ω
20-7311
If it rings a bell to anyone but I'm not worried about the wattage specifics. I popped the top off the sucker cause I've never seen the internals on a large rheostat before, and it's quiet neat and tidy. It is showing a little bit of corrosion though, primarily at the contacts, the motion is still smooth as glass but when connected to my multimeter it was going high limit briefly during rotation so I'm guessing the corrosion is enough that it's making bad contact a bit. I was planning on using vinegar to clean some of the oxide off and then follow up with a good flush with rubbing alcohol to try to clean the contacts up a bit, but what would I be able to put on afterwards to help protect against corrosion but not screw with the electrical side of things? I was thinking oil but it's too good an insulator, and I'm not sure if the contact pressure would be enough to displace a thin oil coating. Is there anything that would work? Or would I just be better off cleaning the crap out of it and buttoning it up again relying on isolation to keep it from corroding?
I googled the markings on the rheostat but came up with zip,
They are
CM39771
25Ω
20-7311
If it rings a bell to anyone but I'm not worried about the wattage specifics. I popped the top off the sucker cause I've never seen the internals on a large rheostat before, and it's quiet neat and tidy. It is showing a little bit of corrosion though, primarily at the contacts, the motion is still smooth as glass but when connected to my multimeter it was going high limit briefly during rotation so I'm guessing the corrosion is enough that it's making bad contact a bit. I was planning on using vinegar to clean some of the oxide off and then follow up with a good flush with rubbing alcohol to try to clean the contacts up a bit, but what would I be able to put on afterwards to help protect against corrosion but not screw with the electrical side of things? I was thinking oil but it's too good an insulator, and I'm not sure if the contact pressure would be enough to displace a thin oil coating. Is there anything that would work? Or would I just be better off cleaning the crap out of it and buttoning it up again relying on isolation to keep it from corroding?