Build Your Own Clone Message Board

Hey there - I´ve got some trouble getting the Mega Chorus running: Dry signal part is running just fine, the wet signal is completely dead.
I really want to get there by my own but I got some troubles understanding the schematic - in particular the power supply: The BBD (3207 in my case) has vb on pin 5, which is not mentioned in the PS-section - is that "vb" +v2, +v or 1/2vb? Also the bias voltage is referred to as 1/2v, which is 1/2vb from the PS-section I suppose?

So should the bbd supply be around 9V, bias around 4,5V (adjusted for minimum distortion)?

Anyway - thanks and keep up the great work!

Hey thee DanielSan - welcome to the forum!

Yeah, I've noticed before that this schematic is a bit of a mess. I'm not sure what Vb shown on BBD pin 5 is; I think that it may actually be +V2 in the power section, as that is how MN3207s are typically set up. You can check that out by measuring continuity from pin 5 to to R56.

Yes, I believe the power nodes labeled 1/2v are connected to 1/2vb (the trim pot output).

BBD supply on pin 5 is typically a little less than 9v and yes, I usually find the best results when the BBD output (pins 7 and sits right around 4.5 volts.

A signal tester is very useful for diagnosing these types of circuits when the wet signal path is dead.



http://byocelectronics.com/megachorusschematic.pdf

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