01-23-2011, 09:07 PM
You say you've replaced most of the capacitors and resistors...have you replaced the electrolytic capacitors? These are usually the culprit when the complaint is loud humming or buzzing.
Other possibilities: bad ground connection(s), heater-cathode short in a tube, poor solder connections, miswiring/a component mistakenly soldered to the wrong place.
The 6F6 tubes (the 37-650 uses two of these) will run hot; too hot to touch in normal operation. As for the blue glow inside, if the blue appears to be just inside the glass, than the tube is probably OK. But if the glow in inside the tube elements and more purple than blue, then the tube is definitely bad.
Other possibilities: bad ground connection(s), heater-cathode short in a tube, poor solder connections, miswiring/a component mistakenly soldered to the wrong place.
The 6F6 tubes (the 37-650 uses two of these) will run hot; too hot to touch in normal operation. As for the blue glow inside, if the blue appears to be just inside the glass, than the tube is probably OK. But if the glow in inside the tube elements and more purple than blue, then the tube is definitely bad.
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Ron Ramirez
Ferdinand IN
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