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Vintage threads from the first ten years
59' 5F6A problem
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 8/1/2005 1:07 PM |
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Dustee |
59' 5F6A problem I have a 59 5F6A that has been rebuilt and was working fine until it smoked a cap. I have checked all of the resistors in the bias supply and changed the bias supply caps and diode in place of the selinium rectifier.New tubes.New screen resistors. When I fire it up (even without power tubes) it blows out one of the 10uf@100VDC bias caps.They are installed pos to ground and the diode is installed correctly. Any ideas where the problem may be? Thanks Dustee |
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| 8/1/2005 3:24 PM |
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| Ray Ivers |
Dustee, I would check all the PT secondary VAC's, especially on the bias tap. Ray |
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| 8/1/2005 4:36 PM |
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| Dustee |
Thanks for the reply Ray.That would have been my first thought too but it's a brand new Mercury Magnetics replacement transformer. I'll still unsolder the leads and check them . Thanks |
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| 8/2/2005 7:36 PM |
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| peter |
What Ray said, plus check the coupling caps going from the PI plates to the power tube grids. If one of these is shorted you may have about somewhere between 210vdc and 230vdc going into the bias circuit which could pop one of the bias supply caps....I can't really think of any other possibilites at the moment. peter |
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