Hyper Fuzz Power Section

[BennyBoy]

Hi folks,

I am cooking up a pretty exciting original modification to the Boss Hyper Fuzz (more to come on that later), but encountered a bit of a problem understanding the schematic I am working from. I am using this schematic from Aion FX, assuming it is true to the original pedal, as it is the most clear schematic I could find online.

I just finished drawing everything in the main circuit in Eagle, only to find that the power section does not include VC and VD, only VA and VB. VC and VD are used in other parts of the schematic. Is there something I am missing here, or is this schematic incomplete/erroneous?

Thanks,
Ben 

[marcelomd]

Looks like a simple mistake.

9V VA -> VC
4.5V VB -> VD

[BennyBoy]

Looks like a simple mistake.

9V VA -> VC
4.5V VB -> VD

Thanks, much appreciated!

[idy]

I think it is a little more confused: around Q6 and Q7 there are three VC connections. Only the middle one seems to be power and the other two appear to be bias mid voltage. Q5 has the same issue, and the collector should be 9v and the base 4.5.

[m4268588]

[aion]

This is a couple weeks old, but just for posterity - this is a sandwich PCB, so VC is VA when on the top board, and VD is VB on the top board, just an artifact of the CAD design. I usually clean this up when prepping the schematic for the build docs but missed this one. I'll get it in the queue for an update.

I think it is a little more confused: around Q6 and Q7 there are three VC connections. Only the middle one seems to be power and the other two appear to be bias mid voltage. Q5 has the same issue, and the collector should be 9v and the base 4.5.

Note the second resistor to ground in each of these cases. The transistors do want a bias voltage here, but this can be done either by a single bias resistor to an existing bias supply or (as in this circuit) a local voltage divider.

The resistor to VB has the potential to be less noisy since VB would have a filter capacitor, so on a new design that's usually a better way to go, but this is how Boss did it for the FZ-2.