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Title: bias question Post by: jerrydyer on June 20, 2008, 03:49:48 PM I have a JTM45 ceriatone on the bench. looks like it was dropped. Installed new power tubes. bias ris runaway. goes up to about 62 watts each before I turn it off should i replace the rectifier and try again? thanx
Title: Re: bias question Post by: bloodedge on June 21, 2008, 03:53:32 PM I had a problem with bias that go out of spect in past.
It happened to be a bad contact with powertube socket. I didnt replace the socket, just tightened it a bit and i never had a problem with this again :). Trough it was happening in only 1 socket/powertube. Am not a pro but here what iwould do. I would check for voltage of the powertubes if you can(taking REALLY care of high voltage) So you can know if the bias circuit supply the powertube correctly, etc. Also, i think it is recommanded to change the rectifier tube when you change the powertubes so it can be this too. Title: Re: bias question Post by: Roe on June 22, 2008, 04:57:30 PM adjust the bias. just change the bias resistor if the range is too high or low
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