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    Building, troubleshooting and testing of these amplifiers should only be
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Capacitor Sanity Check

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So, I'm new to the forums and I'm starting on my first tube project which involves converting an old Grommes/Precision Electronics S35 tube PA into a guitar amp. It's current running two 6eu7's for the preamp, a 6c4 for phase inversion, and 7868's in PP for the output stage.

Before modifying anything I was looking over the schematic, it appears that one of the power filtering capacitors was spec'ed out to 250VDC when its rail is designed to operate at 325VDC. Could this possibly be correct??

full schematic (if interested):http://ampslab.com/SCHEMATICS/GrommesS35.gif
 

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I opened up the amp and verified the capacitor is actually a 10uF 250V cap but haven't had the guts to test the rail voltage with my radio shack multimeter. :D

Since I'm replacing caps anyway I'm going to put in a 10uf/450v and call it good. Thanks for the replies!
 
Get that 250Vcapacitor out of there! That's an accident just waiting to happen. According to that schemo, it's connected to a line that could go as high as 460V, with just resistor series drops to limit the voltage. It should be a 450V capacitor at least.

I don't know if that was an accident, or was done deliberately to keep the knowledgeable from building one of their own, but it's definitely wrong.
 
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