AionFX Convex - Buffered Bypass malfunction?

[zachlovescoffee]

Howdy! I just build this pedal from the PCB only. It sounds pretty tasty though I haven't had a ton of time since I've been wracking my brain on this hiccup.

When the pedal is in buffered bypass mode and the pedal is turned off and the input is set to blend, the signal is dead. Nothing goes through the pedal to the amp. However, if I flip the input to direct (pedal is still powered off) then the signal goes through.

Now, if I switch it to True Bypass mode, it just works all fine. Attached is a video of the weirdness in buffered bypass mode. Maybe I'm just not understanding something about this mode but it seems like it should work?

https://youtu.be/iQtXRjekh7I

[bluebunny]

When you say "powered off" and "turned off", do you really mean completely disconnected from any power supply?  If so, then the buffer (in the "buffered bypass") cannot function: it's a dead-end and silent.  True bypass is a piece of wire connected mechanically.  It always works.

[zachlovescoffee]

Apologies. I meant to say powdered off. 9V still connected but pedal turned off. Signal dead when in blend mode but not direct.

[duck_arse]

the circuit diagram might show why, but I can't seem to see it ...........

[zachlovescoffee]

I'm still learning to read schematics but based on this screen shot it appears that this is by design? It seems that when the switch is down it throws the signal to ground, which I assume means it goes no where. Is that interpretation correct based on how I marked this up? Or, am I missing something? If it is correct, why would you send the signal to ground?



Source: https://aionfx.com/app/files/docs/convex_documentation.pdf, pg. 7, Convex Schematic, 2021.

[MikeA]

You're right on top of it, the fault only happens when Mode switch lugs 1 and 2 are made, so lug 2 has the buffered output signal and takes it to lug 1 of the Balance switch.  Does the position of the Balance switch matter?  If not, my thought is that the trace from Mode lug 2 to Balance lug 1 runs right at the edge of the PCB, and it looks like your PCB might be touching the enclosure on the right side.  See if you can slip a piece of paper in between, or gently pry the PCB away from the right side of the enclosure and see if that helps.  If not, check around that path from Mode 2 to Balance lug 1, and Balance lug 2 to foot switch,  although it looks clean otherwise. 

[idy]

when the switch is down it doesn't throw all the signal to ground, it puts pin 1 of the pot to ground, which is what almost all volume controls do. When switch is up, pin 1 goes to the dry buffered signal to allow mixing. So if the pot is on 0, it should produce no sound when it is working as a volume control.

[zachlovescoffee]

You're right on top of it, the fault only happens when Mode switch lugs 1 and 2 are made, so lug 2 has the buffered output signal and takes it to lug 1 of the Balance switch.  Does the position of the Balance switch matter?  If not, my thought is that the trace from Mode lug 2 to Balance lug 1 runs right at the edge of the PCB, and it looks like your PCB might be touching the enclosure on the right side.  See if you can slip a piece of paper in between, or gently pry the PCB away from the right side of the enclosure and see if that helps.  If not, check around that path from Mode 2 to Balance lug 1, and Balance lug 2 to foot switch,  although it looks clean otherwise.

Winner winner chicken dinner!!! I slipped a piece of paper between the PCB and enclosure and I now have signal! Damn that's crazy good eye work. Thank you!!!

[zachlovescoffee]

Crap! I was wrong. I didn't move the pedal into buffered bypass mode. So, even with the paper installed,  in "blend" with the pedal powered off, there is no sound. UGH. Back to the drawing board.

[zachlovescoffee]

I got it sorted out. No idea what the problem was. I had continuity at the switch to the output in blend mode. I just took everything apart and re-fitted it in the enclosure and now it works. C'est la vie!

[MikeA]

Congrats! Sometimes you just have to take it apart one more time.