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June 25, 2022, 07:32:56 AM

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Correcting Headphone Jack to cut Speaker out - Yamaha G50

Started by SemiConductive, May 03, 2022, 04:43:03 PM

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SemiConductive

#15
Quote from: Enzo on May 05, 2022, 09:14:38 PMYou have three LEDs - plus power indicator -  A, B, and P?  I'd wager channel A, channel B, and Peak.
I'd check the IC for function

Quote from: g1 on May 06, 2022, 12:19:43 PMIs there a jack for PEQ footswitch?  I think you may be able to turn it off and on so you can use it like a lead boost etc.

Ah, g1, I think you nailed it.

I thought the footswitch was a simple  A/B channel switcher. It's just a TR type jack. But after digging into the schematic and the service manual, I see the footswitch controls the A/B channel switching, the P-EQ, and the Effects loop (S models only).

So they multi-plexed the three functions onto a two wire footswitch. All the extra circuitry is supporting the switching functions. And the reason the LED never goes off is that I don't have absolute switching on the control panel. I can set levels to 0 effect, but I can't actually "shut it off" - which can be done with the foot switch.