Does anyone have a Boss OS-2? Need help.

[bean]

I'm needing voltage readings on three pins (trying to figure out a build issue and whether or not it is PCB related or something else). They correspond to IC1A pins 3 through 1 (the SIL op-amp). I've highlighted them in the red box in the image below. Many thanks in advance.

[m4268588]

I don't know if this answers your question, but I heard that there are errors in the schematic.

[bean]

I don't know if this answers your question, but I heard that there are errors in the schematic.

Yes, that is my thought as well. Specifically, that pin3 needs a resistor to Vb like your image shows. But, I'm reading a stray voltage on my board which I think might be from a manufacturing error. Thanks.

[music_circuits]

PedalPCB did an OC-2 PCB, maybe he can help on this

[bluebunny]

I found a schematic that has 100K from pin 3 to VR (missing from the others I've found so far).  Then I guess you'd expect to see VR at pins 1, 2 and 3?

[bean]

I found a schematic that has 100K from pin 3 to VR (missing from the others I've found so far).  Then I guess you'd expect to see VR at pins 1, 2 and 3?

Thanks for that. Had not seen that one. I've been comparing different gut shots I can find on the OS-2 but so far have not identified an extra resistor on pin3. I tried a couple different resistors b/w pin3 and VB (vcc/2) and had to go all the way down to 10k to get around 4.5 on all three pins (3, 2, and 1).

Overall the circuit has more output than needed, so I may reduce that 150k in the feedback loop to 22k. Other than that, it sounds pretty dang crunchy - in a good way!