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HELP: DC at the input of an old MA1's.

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Hallo All,

Is anyone familiar with this: When “pre glowing” my old MA1 (with the 12 tubes and the 6DJ8 at the input) there is (after a few seconds) a negative voltage of 90-110 Vdc at the input of the XLR (and cinch). The DC is there for maybe 1 or 2 seconds and rapidly disappears! I did have some problems with a DAC when I started up the AtmaSphere’s and disconnect the DAC. There is also a DC peak when shutting down the amplifier. This DC appears after some seconds and stays a little longer on the inputs!
The High Voltage switch after the “pre glowing” did not have any effect. I use the E88CC (Siemens) instead of the 6DJ8, but both tubes (and both Amplifiers) do have this DC!! My amp is one off the first MA1’s with 3 driver tubes and 12 6AS7G’s. I do have the 1 Ohm plate resistors ánd the 5 Ohm cathode resistors and the Teflon coupling Caps. The input resistance is 500K (ground-hot and ground-cold). Please anyone out there???

Thanks
Robert


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