Polarity based caps

knowledge base for the classic Dynaco ST70

Polarity based caps

Postby Clik2media » Mon Jan 04, 2010 11:52 pm

On the 7199 board, pray tell which direction does currwnt flow, or, according to Auricaps and I quote " In all coupling applications the input to the Auricap should be the black lead and connected to the signal source or circuit output with the red lead continuing on to the next circuit input. "
Any help....
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Postby mesherm » Tue Jan 05, 2010 3:52 am

On a stock ST70 driver board the end of the caps facing outward go to the grids of the EL34s which is the "next circuit input". So wire your caps so the red leads would all face outward and the black leads all face inward toward the center of the board which is the "signal source or circuit output".
Mike's N-1 Rule: When looking for N number of components to finish a job, you have a 95% chance of only finding N-1 of them.
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Postby Clik2media » Tue Jan 05, 2010 3:29 pm

Thanks very much for your reply, can I clarify the inside caps [two], Looking at the front of the amp, where would the red leads face?
Thanks very much
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Postby mesherm » Tue Jan 05, 2010 4:33 pm

If you mean the two 0.047mf caps, they are screen decoupling caps and are not in the signal path. If I had to pick a direction though, I would orient the caps with the black leads to the front (pin 6 or the 7199). That would put the black lead closest to the pentode section's cathode, closest to ground potential.
Mike's N-1 Rule: When looking for N number of components to finish a job, you have a 95% chance of only finding N-1 of them.
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Postby Clik2media » Tue Jan 05, 2010 4:47 pm

I can see I have much , make that very much more to learn, and this certainly seems like the right place. I once again thank you, and I will post some pics of the final, plus my sonic opinion, however challenged that may be.
cheers
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