I'm currently working on an Ampeg VT22 that seems to have the original RCA labelled power valves in it. One is pulling 71mA at idle, one 34mA and the other two approx 54mA. I've swapped a couple round to make sure it's the valves and not the circuitry. Needless to say I intend to replace these valves. Has anyone had any issues with the JJ 7027's with plate voltages around 560Vdc? (Max value on data sheet is 500Vdc although the triodeelectronics page suggests that the JJ's are fine in Ampegs). All the grid resistors check fine (47K) with the bias voltage sitting at -48Vdc. I've located and changed a few dead components. Would it be best to back off the bias a bit to bring the idle current back down to approx 30mA with the JJ 7027's? This would just involve increasing the grid resistor values yes? Perhaps to 56K?
Any help appreciated.
Any help appreciated.