#16
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Do you still measure a high voltage between the chassis and b- ?
jr |
#17
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No hv neg to chassis I obviously went from b+ to chassis. My mistake.
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#18
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What do you hear if you disconnect the grid (pin 2) of the 25L6 audio output tube.
jr |
#19
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I didn't disconnect anything else but pin 2 of the 6sq7, still humming.
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#20
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Quote:
jr |
Audiokarma |
#21
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Are the filaments in series, or is it possible to pull the audio amp tube and see what happens to the hum? Do you have a tester to check the audio output tube for heater/cathode short, or a spare output tube?
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#22
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Well I could take off pin 2 but nothing will happen, heater. Or you meant grid I think ?
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#23
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I tried 2 other tubes both of them and my tester does check for shorts. It is series.
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#24
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Quote:
jr |
#25
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Pin 5 off hum even louder with no hiss as if there was no ant.
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Audiokarma |
#26
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Interesting.
What happens if you connect pin 5 of the 25L6 to either end of the cathode resistor (330 ohm R-38) ? Try both ends. jr |
#27
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After the grid wire was put back on?
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#28
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Ok, either side of the 330 resistor it blanked out the audio all together.
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#29
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Well the 330ohm resistor checks at .336k so I have a new 330ohm resistor that checks just that so I'll change that resistor tomorrow. One end of that resistor goes the cap at the amp . maybe it cannot filter because of that resistor being high.
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#30
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Seems like it coud be leakage from the grid to the heater pins.
Is the socket dirty or perhaps charred? Bad insulation on wire to the grid? jr Edit add: Why change a resistor that is only 6 ohms off? That is less than 2% off. Last edited by jr_tech; 03-26-2018 at 06:41 PM. Reason: add question |
Audiokarma |
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