PedalPCB Roboto weirdness

[p_wats]

Hey guys,

This is a strange and frustrating one that I've entirely caused by being in a rush and making dumb mistakes, but here goes:

I populated a PedalPCB Roboto PCB (http://www.pedalpcb.com/product/roboto/) recently and it worked perfectly fine (and sounded really cool), but I soldered the board-mount pots on backwards, so the volume sweep was off. I knew it would nag at me, so I decided to flip them around to correct their orientation.

Of course, after doing that it has never worked correctly since. My assumption here is that, because everything else was already populated I may have fried a sensitive component, so I replaced all nearby electrolytics, 3.3v regulator and even the TL072 & 8950, just in case.

This brought things somewhat back to life, but now I'm more confused, because out of the 4 modes only the 1st and last work (fuzz and arp). The middle positions (up and down) sound like they are trying to work, but have very little volume.

All knobs respond in a seemingly correct manner too. The only thing I can think of is that something is happening when the microcontroller switches into the 2 middle positions, but why would it only affect those 2 and not the others, as the circuit is pretty simple. In any case, I've beaten my head against a wall and was hoping for some advice before I masochistically replace all the rest of the passives.

Here's the schematic: http://www.pedalpcb.com/docs/Roboto.pdf

Thanks!

[p_wats]

Follow up for posterity: I put this aside for a while while I finished some recordings. Went back to it last night. Replaced components and reflowed others, but the middle 2 sections still sound off. For the sake of my sanity I just replaced the mode pot with a toggle switch that selects between either Robot/Fuzz or Arp.

I have 5 more HT8950 chips, so I may order another Roboto board and try again to see if I get better results. We'll see.

[diablochris6]

That is am odd issue. Did you use an audio probe to see if the issue was in the audio path? Record voltages? Swap out the HT8950 chips to see if it's a bad chip?

[p_wats]

I picked up a few extra HT8950s, so went ahead and ordered another board from pedalPCB too. He was kind enough to send me an extra, just in case.

In the end the 2 new boards worked fine (1 needed some probing, as there wasn't continuity between 2 places where there should have been) and I was able to use the working boards to confirm my voltages were off on the first board (only at the HT8950), but that board was already a bit beat up from some blind troubleshooting, so I scrapped it in favour of the 2 working boards I've now got.