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Old 31st October 2009, 06:57 PM   #1
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Default C450 Radio Craftsmen info needed

I'm trying to get this old tube amp to work but have no schematic or info of some sort. I was busted when picked it up years ago and got the 6sn7 replaced. 6W6 (6V6?) and rectifier are OK. The amp distorts very badly a few minuts after turn ON. Seems like someone work on it before, so who knows if something is missing, fried or connected wrongly.
Help anyone?
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Old 31st October 2009, 10:08 PM   #2
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Greetings from FixitLand!

Quote:
Originally Posted by pliedtka View Post
I'm trying to get this old tube amp to work but have no schematic or info of some sort. I was busted when picked it up years ago and got the 6sn7 replaced. 6W6 (6V6?) and rectifier are OK. The amp distorts very badly a few minuts after turn ON. Seems like someone work on it before, so who knows if something is missing, fried or connected wrongly.
Help anyone?
I don't see a schematic at Nostalgia Air for that model either. The symptom you describe sounds like a leaky coupling capacitor, most likely at the output-tube grid. A leaky cap develops a gradually-increasing positive grid bias, which causes the tube to conduct heavily. The result is a "growly," distorted sound accompanied by increased hum due to heavier power-supply load. Change out any and all waxed paper capacitors. You might have to make up your own schematic. Take your time and be careful. Is 6SN7, 6W6 (or 6V6) and the (whatever) rectifier the entire tube complement? If so, that should be a fairly simple amp to draw out.

Take care,
--
J. E. Knox 'The Victor Freak'
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Old 7th April 2010, 04:38 PM   #3
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Pliedtka, you have mail.

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