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Hi Kevin
I measured 392V from chassis to the first power filter cap. As for the cathode voltage from Rk to chassis I measured around 12V.
With the original Rk I remember achieving hum balance and current varied with the pots at the test points. For a cathode bias adjust circuit what kind of range am I looking at? Definitely not 0.8mV max difference from "o" to "x" am I right? Or is that how it is designed.
Currently I have grounded the MV ground lug pot "o" to ground while that same lug has another wire going to the wiper of the bias pot. Otherwise the MV is always open and I cannot control it. In my first setup I had no ground to pot "o" but it went only to the wiper. With this setup the bias seemed to work but the MV was now open so I also tied it to ground.
Is this correct?
One thing also to note is currently I am using test leads to connect to the bias pots and other circuitry to make sure it is working as it should.
Also to note is once that tube red plated is it possible that the tube is damaged and so bias adjust doesn't work? I can still play through the amp and it sounds good but could there be a defect now with the tube?
I measured 392V from chassis to the first power filter cap. As for the cathode voltage from Rk to chassis I measured around 12V.
With the original Rk I remember achieving hum balance and current varied with the pots at the test points. For a cathode bias adjust circuit what kind of range am I looking at? Definitely not 0.8mV max difference from "o" to "x" am I right? Or is that how it is designed.
Currently I have grounded the MV ground lug pot "o" to ground while that same lug has another wire going to the wiper of the bias pot. Otherwise the MV is always open and I cannot control it. In my first setup I had no ground to pot "o" but it went only to the wiper. With this setup the bias seemed to work but the MV was now open so I also tied it to ground.
Is this correct?
One thing also to note is currently I am using test leads to connect to the bias pots and other circuitry to make sure it is working as it should.
Also to note is once that tube red plated is it possible that the tube is damaged and so bias adjust doesn't work? I can still play through the amp and it sounds good but could there be a defect now with the tube?
