BOSS SD-1(C) Issue: Pedal cannot be turned off

Started by MothGarden, November 27, 2023, 10:32:37 PM

Previous topic - Next topic

MothGarden

This seems to be an issue with JFET switching pedals. It doesn't help that this pedal is one of the newer models with surface mounted components. I took some measurements of the transistor outputs to see if anything can be diagnosed with this pedal. The switch is functional (tested with multimeter) and shorting the switch contacts does not seem to change anything. The marking on the transistors I believe is "LG". The labeled image below is my best guess as to the what the orientation of the transistors are based off of similar looking transistors I found online. The labeling of Q1 and Q2 is only there for the sake of differentiating them. I think they would be Q3 and Q4 on the original schematic for the board, although I'm not sure which is which in my image. I'm thinking if there is no simple fix to this, then it might be a good candidate for a true bypass mod ;)



Q1
C: 8.82
B: 0
E: 0

Q2
C: 0.058
B: 0.666
E: 0

Edit: Forgot to include more info on the problem. Pedal turns on automatically when power is provided and a jack is plugged into the input, switch will not turn the effect off