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Post by duck72701 on Oct 4, 2004 0:53:23 GMT -5
Before I did the bais mod I checked the negitive volts at pin 5 and it read -57. I have burned up two sets of tubes, after doing the mod I checked it agin, still the same thing, with 15 0hm at the trim pot. I got the amp 2nd hand, is this right or has some one moded this amp and mested it up?
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Post by Jerry P on Oct 4, 2004 8:56:19 GMT -5
Before I did the bais mod I checked the negitive volts at pin 5 and it read -57. I have burned up two sets of tubes, after doing the mod I checked it agin, still the same thing, with 15 0hm at the trim pot. I got the amp 2nd hand, is this right or has some one moded this amp and mested it up? The bias voltage at pin 5 tells you very little about the actual bias setting. You can plug in 3 different sets of tube and leave the bias setting at -57 but if you checked them with a bias probe they would all have different current draw. The bias mod uses a 10K pot, not a 15 ohm pot. A 15K could be used but 15 ohm is WAY too small to do anything. I'd take it to a tech. If you have a 15 ohm pot and it reads -57 on pin 5 the bias mod was done wrong. Jerry |
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