diy tube amp problem

ectobia · 14th June 2006, 05:31 PM

I changed 300b tubes with new ones after the tube amp was unplugged from the wall for a while, and smoke started coming out from the tubes,then I turned it off and unplugged it, I made sure all the tubes were plugged in the socket before turning it on. Then I tried it again and hear a very strange noise coming from the amp. So I took them out and then I noticed brown burn marks at the top of the tubes. I put the original ones back in and they didn't burn but I heard the strange noise coming from the tube amp so I shut it off immediately. What should I do? Is this could be caused by a bad tube socket, or just a bad solder point.. anything else that could cause this problem?

thanks

alexmoose · 14th June 2006, 06:04 PM

what kind of noise was it? was it a low hum? are you using AC, or DC heaters?

Kyle K · 14th June 2006, 07:12 PM

Some new production 4-pin sockets have holes that are large enough to plug a tube in the wrong way. Could that have happened?

selfwilly · 14th June 2006, 08:36 PM

my first thought too ,kyle, i hate to say it, i've done this! when i saw the current meter instantly slam over to max rather than the slowish climb up , i shut it down! the tube plays to this day-good advertising for jj!

teemuk · 14th June 2006, 08:50 PM

Judged by ectobia´s description I think that the tubes were possibly bad, plugged the wrong way around or whatever. This caused a short somewhere in the circuit - which still exists - and now the high current in the mains transformer "resonates" its windings, thus the "strange sound from the amp".

14th June 2006, 05:31 PM	#1
ectobia diyAudio Member Join Date: May 2006	diy tube amp problem I changed 300b tubes with new ones after the tube amp was unplugged from the wall for a while, and smoke started coming out from the tubes,then I turned it off and unplugged it, I made sure all the tubes were plugged in the socket before turning it on. Then I tried it again and hear a very strange noise coming from the amp. So I took them out and then I noticed brown burn marks at the top of the tubes. I put the original ones back in and they didn't burn but I heard the strange noise coming from the tube amp so I shut it off immediately. What should I do? Is this could be caused by a bad tube socket, or just a bad solder point.. anything else that could cause this problem? thanks

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14th June 2006, 06:04 PM	#2
alexmoose diyAudio Member Join Date: Mar 2006 Location: Michigan	what kind of noise was it? was it a low hum? are you using AC, or DC heaters?

14th June 2006, 07:12 PM	#3
Kyle K diyAudio Member Join Date: May 2003 Location: Mililani, HI	Some new production 4-pin sockets have holes that are large enough to plug a tube in the wrong way. Could that have happened?

14th June 2006, 08:36 PM	#4
selfwilly diyAudio Member Join Date: Jan 2005 Location: new england	my first thought too ,kyle, i hate to say it, i've done this! when i saw the current meter instantly slam over to max rather than the slowish climb up , i shut it down! the tube plays to this day-good advertising for jj!

14th June 2006, 08:50 PM	#5
teemuk diyAudio Member Join Date: Nov 2004 Location: Suomi, Finland	Judged by ectobia´s description I think that the tubes were possibly bad, plugged the wrong way around or whatever. This caused a short somewhere in the circuit - which still exists - and now the high current in the mains transformer "resonates" its windings, thus the "strange sound from the amp".

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