Bias Problem

[Mr. Big]

I noticed that the bias on one of the tubes in my Ref75 was way out of adjustment and I can't get it back into its proper range with the adjusting tool. Does this mean that the tube need to be replaced or is there another issue with the amp? I have about 1500 hours on the KT120s so I should replace them anyway. And can anything bad happen if I continue to use the amp while it's in this state?

[jakegt3]

It could be a bad tube or something gone wrong in the bias circuit. To test for a tube problem, swap the tube in question with one from a different tube slot. If the problem moves with the tube, then the tube is bad. If it stays in the same slot, it's most likely a circuit problem.

[Mr. Big]

Originally Posted by jakegt3

To test for a tube problem, swap the tube in question with one from a different tube slot. If the problem moves with the tube, then the tube is bad. If it stays in the same slot, it's most likely a circuit problem.

Thanks for the advice. Yep, it's a tube problem. I switched slots and the problem moved with the tube.

[TMcD]

Originally Posted by Mr. Big

Thanks for the advice. Yep, it's a tube problem. I switched slots and the problem moved with the tube.

Good news. That's an easy fix.