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carver TFM-25 amp

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negbias

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Posts: 6

Joined: Sat Nov 01, 2014 6:34 pm

Post Sat May 13, 2017 8:54 pm

carver TFM-25 amp

can the output relays on the carver TFM-25 be cleaned?
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radioeng2

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SILVER-7 TUBE AMP

Posts: 2553

Joined: Fri Jan 26, 2007 7:06 pm

Location: E TN

Post Sun May 14, 2017 7:17 pm

Re: carver TFM-25 amp

Hello,

Since no one with direct experience has answered yet, let me throw in a little about cleaning relays.

I'm used to big open frame relays used for higher voltages. And some of the what I think of as medium sized ones that are about an inch square or so. On these types, I carry and use a special file made just for contact cleaning, a burnishing tool. On a relay that opens and closes with enough potential on it, the action of the contact movement will have a small spark across it. This over time builds up carbon and some pitting maybe if the potential is enough. The file action will clean off the carbon, smooth the pitting a little. But even then it's regarded as bettering it for now. It probably won't last. It's best to replace if much problem follows.

In lower current applications, I think of contacts in relays much like in switches. The make up of the materials varies depending on the application. For instance, low current, like for line level audio, has next to no current. So silvered contacts are necessary. I'd worry that in the case of contacts like that, you'd strip away the necessary plating and essentially ruin the contacts.

In the case of the output relays, they aren't that low of current. Lower voltage and some current I'd think. They probably are built in what they consider a sealed environment. In bigger relays, they are built with tabs that you can carefully use to pry off the top cap, clean the contact and snap back down the top. In the mini ones in consumer electronics, I'd not expect them built to open. Now can you? I have no experience in them. That's why I'd prefer someone that fooled with them to answer. I'd wonder if a tiny hole could be drilled and spray in a contact cleaner and then resealed in some way. I'm not suggesting this and I don't have any experience. But I'm wondering.

You should be able to look up the part number right off the top of the relays and order them from somewhere like Digi-Key or Mouser. Primarily they are rated for the contact voltage being used, the contact number and styles, and the type of footprint. Unless you're sure of what you're doing, then I'd assume it's best to pass it to a service person. Not complicated, not expensive for just the relay. Likely about 8 points per to unsolder and resolder. Should be close to a bench minimum + parts if that's all that's wrong.

Hopefully someone with direct experience will be along. Otherwise, I hope my rambling will help with some understanding in someway of what's involved.

Mark
I was there for the 10th Carverfest! Glad you were too! Or you should have been...

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