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I was trying a different set of output tubes in my Super Reverb Reissue and it started sounding awful. Both output tubes light up with heater current but only the one on the right (looking at the back of the amp) has the blue glow when I take it off standby. Swapping tubes gives the same result so I am confident that the problem is not a tube. When I check the idle current I get a reading if 1mA on the inactive tube and 32 on the working one. The cathode to ground measures 1.2 Ohms. Plate voltage is good at 468. Everything I know to check on the top of the tube socket appears good. My best guess is that the tube socket is not making a connection to the tube , but I do not know how to check this. Looking at the bottom of the tube socket I did not notice any damage, all the contacts looked identical. Any suggestions?
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You mentioned cathode and plate, pins 8 and 3, but what about the screen and control grids? Pins 4 and 5? You need to have B+ on pin 4 and the bias on pin 5.Education is what you're left with after you have forgotten what you have learned. -
Bias voltage is good and I'll have to check the screen voltage. Is there any way to see if the tube socket is making good contact? This happened in the course of swapping out tubes. The tube closest to the rectifier tube barely gets warm, just the heater but no current.Comment
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Brilliant! CHecked pin 4, no voltage, traced it back to R63. What would cause this? I imagine one of the tubes I swapped in was bad. I will throw them out. Any is removing the circuit board as straightforward as it appears, or are there any special instructions? I Assume I need to removeit to replace the resistor.Comment
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