Hammond M3 Amp - Pedal note leaking into the amplification of the Manuals

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bcmatt
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Hammond M3 Amp - Pedal note leaking into the amplification of the Manuals

Post by bcmatt »

After a bunch of trouble shooting and even totally disconnecting the feed from the bass pedal amplifier section into the rest of the amplifier at Point "D" (where the vibrato scanner and percussion signal also feed into the circuit), the last not played from the pedals is faintly heard when playing the keys.
M3.jpg
Even pulling the pedal amplifier tube (the 6ab6) doesn't stop this faint note from coming through when playing the keys.

So, all I can fathom is that the note is riding either through the ground or the B+ connections.
Does anyone have any thoughts for troubleshooting this?
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Stevem
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Re: Hammond M3 Amp - Pedal note leaking into the amplification of the Manuals

Post by Stevem »

It could be coupling thru the PS , or if a coupling cap was replaced that’s near grid wire to one of these sections or near cap then the replaced cap could be the culprit if it was installed such that it’s input end is not self shielded any more.
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bcmatt
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Re: Hammond M3 Amp - Pedal note leaking into the amplification of the Manuals

Post by bcmatt »

Stevem wrote: Thu Jun 13, 2024 8:16 pm It could be coupling thru the PS , or if a coupling cap was replaced that’s near grid wire to one of these sections or near cap then the replaced cap could be the culprit if it was installed such that it’s input end is not self shielded any more.
Interesting, ok, thanks. I'll take a look.
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