What you saw was a tube arcing. I saw it once on a Rogue Cronus Magnum. The tube had a blue arc going up and down it. I replaced the tube and also the fuse that was in line with each tube, then had to rebias.
Did I just ruin my amp
First, this is my first tube amp hence the dumb mistake. Over the past few days my stereo has been making an intermittent high pitch squealing sound which I thought was caused by some ground or feedback issue but now see was a power tube dying. Yesterday my wife said she heard some weird sound coming from the speakers. She called me in and I saw what looked like fire in one of the power tubes. I immediately unplugged everything and that is where things now stand. Help on what to do next would be appreciated. I have a full set of extra power tubes which I was thinking of putting in the amp but I wanted to hear from more experienced people before doing this. Thanks.
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I think @stereo5 is correct, it’s alarming but nothing to worry about. Depending on what the amp is you may have also lost a protection resistor. I used to own AirTight amps that blew power tubes with great regularity and every time I needed to solder in a new resistor. Needless to say I keep plenty on hand let us know what amp it was |
Replacing a fuse should be very easy, first make sure the amp is off. Looking at the back of some Melody amps online it looks like the fuse is in a compartment above the iec power inlet. You should be able to just pop that out with a flat bladed screwdriver and there is your fuse. The value should be on the fuse itself and it's also printed on the back below the iec inlet. Go to Radio Shack or any electronics store get a replacement fuse and pop it in. I concur on the arcing tube which is in and of itself not a big deal but if you're getting noise probably time for a retube anyway. Good luck! |
If this is your amp it appears to have one fuse integrated in the power socket on the rear. Nowhere does it divulge the value of the fuse or whether it's fast- or slo-blo. It also appears to be self-biasing. http://www.melodyamplifier.com/wp-content/uploads/2014/07/DARK-EL34-MULTILINGUE.pdf |
As jond and twoleftears mentioned I took out the fuse holder that was integrated into the power socket. Took a look and not only does there seem to have a backup fuse located in the part that I pulled out but the original fuse seems to be intact. Perhaps I got to it before it blew. kalali - I bought the unit used a while ago and while I believe the amp to be really well made I had been warned that the tubes that Melody included are junk. |
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I would change all el34 tubes with new ones. It’s costly but you said they are junk. Your amp should be ok but if you want to feel little better, open it up and visually check it over, especially little resisters for off colors. Replace them tubes and make sure to adjust bias if it’s not auto bias and make sure it’s stable. Make sure to keep speaker cables hooked up whenever you power up a tube amp. |
Agree with @jond about the Genalex KT-77s but if the price is a barrier there are several good options. I would recommend you get in touch with Jim McShane. Incredibly knowledgeable and helpful with fully tested tubes at fair prices. I don't buy tubes from anyone else. www.mcshanedesign.net/ |
As others mentioned I think you did see a tube arcing. If your power tube went bad, that doesn't necessarily mean you blew a fuse. If the fuse is not blown there is no reason to replace it, unless it makes you feel better. As mentioned when replacing tubes, some require bias adjustments while other amps have self-bias of tubes. It also doesn't mean that any other part of the amp is damaged. Should you continue to have this problem I'd suggest having the unit professionally checked out. When tubes go bad sometimes it's a quiet venture and other time it can produce very loud weird noises. Let us know how it all turns out. |
I want to again thank everyone for the helpful tips. I had already purchased some preferred series tubes from thetubestore but was waiting to put those and some expensive northern electric 6sn7 tubes till after Xmas but instead threw them in and the amp sounds better than new. Can’t wait to put the 6sn7 in! |
