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THis might be a little late but
You don't mention which Bedrock model you have. But if it's like mine, then you have well over 500 V B+ on the plates, and very nearly that on the screens.
On mine there was a large wattage (25W?) 1.5K aluminum power resistor with extra heat sink screwed to the middle of the PCB feeding a pair of 5 watt screen resistors on the socket. It had been replaced with a cement replacement wired around it that was also toast. This was a tip off that the screens had pulled some serious current.
I removed the old tubes and replaced with new set of 6l6GC's. I measured the voltage at the screens to be pretty much at B+. I ended up replacing the 1.5 K resistor with much larger resistance, dropping the screen voltage about 100 Volts. and I then I put a 16Uf 500V cap from there to ground as a filter. The screen current dropped substantially and the tubes are now much happier.
I also ended up replacing the crappy bias pot with a multi-turn one with more range in order to properly set the bias. Got the tubes dissipating about 20 watts per with no problems.
Hope this helps.
You don't mention which Bedrock model you have. But if it's like mine, then you have well over 500 V B+ on the plates, and very nearly that on the screens.
On mine there was a large wattage (25W?) 1.5K aluminum power resistor with extra heat sink screwed to the middle of the PCB feeding a pair of 5 watt screen resistors on the socket. It had been replaced with a cement replacement wired around it that was also toast. This was a tip off that the screens had pulled some serious current.
I removed the old tubes and replaced with new set of 6l6GC's. I measured the voltage at the screens to be pretty much at B+. I ended up replacing the 1.5 K resistor with much larger resistance, dropping the screen voltage about 100 Volts. and I then I put a 16Uf 500V cap from there to ground as a filter. The screen current dropped substantially and the tubes are now much happier.
I also ended up replacing the crappy bias pot with a multi-turn one with more range in order to properly set the bias. Got the tubes dissipating about 20 watts per with no problems.
Hope this helps.
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