I did finally manage to get a day and a half to make the second DSET operational but it refuses to bias correctly. I've traced the circuit a dozen times, checked component values, tried to find shorts, checked cap polarities, swapped tubes...no result. The gas regulators both sit on 148v-149v with 15ma of current. With the input shorted I am able to roughly bias the 6e5p/6e6p but a couple of channels only bias to -1.2V (Channel A & C), one to -2.2V (Channel B) and the rest are fine at -4V. When I unshort the input I have 4.5V, yes volts, of DC offset, and the low bias tubes (A & C) actually swing into positive bias, which is strange. Something is not right but I just cannot find it...a day and a half last weekend looking for it and I did not even turn on the soldering iron. Very frustrating. The fault will be found, I just need to be smarter about how I look for it...
So Romy, if you are able to offer any insight into how to find this fault I would be much appreciative. I do understand that you will have much better things to do that hold my hand on this. |
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