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Hi - first tube post. I just took delivery of an Allied 333, aka Pioneer SX-34. 6BM8 x 4, 13 tubes total. All mismatched but correct types.Anyway, with the volume knob fully off, I still get volume thru the speakers - quite a bit actually. All other functions seem normal at this point.
Any advice? I saw the tech docs on Ebay not sell a few days ago, perhaps I should get them and send this in for service. I fully expected to re-tube anyway.
I'll be running this with KLH 17's and JBL L26 with a Pioneer PL-115D,
Thanks for any advice, and if any MSP audionuts know a good tube guy....
Follow Ups:
Thanks. There's also a mis-match in level, so check the pot, roger that. Is the manual absolutely necessary? Minimum is $25 for it and I'd rather pay for tech labor, but the documentation seems appropriate....
You could check around to see if you could download a copy of the schematic diagram. Also, if you are going to retube, stick to the amp and preamp section. If you are going to change output/driver tubes, use a Sharpie laundry marker to number the original tubes in their original positions before you start pulling, so you can return them if a new tube turns cherry red or starts all the other tubes turning cherry red. You should also probably mark the tuner tubes as well. I know this seems like overkill, but the IF section is usually redundant and because each section is matched to the gain of a specific IF tube, failure to have each tube in it's original socket may require you to reallign the whole tuner section. You don't want that if there was nothing wrong with the tuner to begin with.A manual is a good thing to have, but for just spraying out a pot or switch? You don't have to be a dentist to brush your own teeth.
Bah. The tubes were pulled before it shipped to me. I plugged them back in according to the stamped assignments in the sheet metal around the sockets.
And of the volume that remains when the control is all the way down to zero, all you hear is higher frequency information? As Soundbug already said, you have a dirty pot. The dust and grit and goo has accumulated down at the bottom of the travel of the wiper of the pot. Just operating the pot rakes it all there. And there is so much of it that it has, literally , lifted the metal wiper off the carbon track. So now, the metal of the wiper acts as one plate of a capacitor which is capacitively coupled to the signal running on the carbon track. But because the wiper/track is a lousy capacitor, only a couple of picofarads of capacitance, it nevertheless acts as a high pass filter to pass high frequency information and blocking low frequency signal. Try Deoxit R-5 to all the pots and signal switches and rotary switches and things should brighten up.
I think you probably just have a bad volume pot. None of the old pots tracked correctly when new and they certainly dont now. I'd get the service manual anyway but try replacing that pot too. Wouldnt do you any harm.
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