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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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In Reply to: Runaway bias - please HELP! posted by DexysMidnightRunner on June 7, 2014 at 13:25:47:
Let me ask you,when the bias current or voltage goes up on the meter and becomes sporadic,does the plate of the tube get that reddish/orange glow? If it does,the bias pot is suspect or maybe a coupling cap that feeds the control grid of the 845..Take the 845 out of the bad amp and goes to pin one which is the control grid.Put your meter on DCV on the highest scale and then clip your neg lead to ground on the chassis somewhere.Turn the amp on and see what the negative bias voltage is at pin one with reference to ground.It should be a negative DC voltage reading.If it's not,you are in the wrong pin.Once you get the negative reading,leave the meter probe on pin one and move the bias pot up and down to see if the negative voltage goes up and down depending way you turn the pot.If its real sensitive,change the pot.If that doesn't do it,the tube or the cap is suspect and I have seen more than one bad tube in a row.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
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- RE: Runaway bias - please HELP! - Michael Samra 23:06:21 06/08/14 (0)
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