spescatore
New member
Hi all, I'm relatively new to DIY effects and have run into something that exceeds my knowledge and troubleshooting abilities - hoping someone can give me some pointers!
My latest build is the Artemis Mk 2 from Aion FX, a Catalinbread SFT v2 clone. The issue I'm having: I do get output when the pedal is on, but 1) there is no noticeable overdrive, even when all controls are maxed, and 2) signal output level is very low unless the gain control is nearly maxed. The output level falls off very quickly once you turn the gain control below maybe 90% of max, and then is virtually inaudible below that. With gain maxed, the signal is definitely amplified a bit relative to when the pedal is bypassed - more so when it's on "stoner" mode versus "stones" mode, which I think is to be expected. But again, no overdrive. Notably, the volume, bass, and treble controls do appear to affect the signal as intended in terms of level/tone.
I'm confident at this point that I've isolated the issue to the main PCB - i.e., not footswitch daughter board, power, input/output, enclosure/grounding, etc. I inspected all my solder joints and didn't see anything concerning, but reflowed everything just in case. I'm also relatively sure all the component values are correct and transistors / caps are seated the right way around. I was initially suspicious of the gain pot, but it's seated well and resistance across that pot (and all others) measures as expected. Finally, I tried to trace the audio signal and see if I could find the overdriven output hiding in there somewhere, but no success - as I mentioned, I do get output end-to-end so, it seems to be something a little more nuanced. That brings me to the stuff I'm still really naive to... I measured voltage on the JFETs (MPF4393, which I got from Aion FX) and got the following readings:
(Edit: updated with corrected source pin readings)
Based on what I've cobbled together from various threads on SFT clones, these values seem to be close to expected - but I'm really not sure how close is good enough or what they suggest (or why). Still learning. Any help much appreciated - thanks!
My latest build is the Artemis Mk 2 from Aion FX, a Catalinbread SFT v2 clone. The issue I'm having: I do get output when the pedal is on, but 1) there is no noticeable overdrive, even when all controls are maxed, and 2) signal output level is very low unless the gain control is nearly maxed. The output level falls off very quickly once you turn the gain control below maybe 90% of max, and then is virtually inaudible below that. With gain maxed, the signal is definitely amplified a bit relative to when the pedal is bypassed - more so when it's on "stoner" mode versus "stones" mode, which I think is to be expected. But again, no overdrive. Notably, the volume, bass, and treble controls do appear to affect the signal as intended in terms of level/tone.
I'm confident at this point that I've isolated the issue to the main PCB - i.e., not footswitch daughter board, power, input/output, enclosure/grounding, etc. I inspected all my solder joints and didn't see anything concerning, but reflowed everything just in case. I'm also relatively sure all the component values are correct and transistors / caps are seated the right way around. I was initially suspicious of the gain pot, but it's seated well and resistance across that pot (and all others) measures as expected. Finally, I tried to trace the audio signal and see if I could find the overdriven output hiding in there somewhere, but no success - as I mentioned, I do get output end-to-end so, it seems to be something a little more nuanced. That brings me to the stuff I'm still really naive to... I measured voltage on the JFETs (MPF4393, which I got from Aion FX) and got the following readings:
(Edit: updated with corrected source pin readings)
Based on what I've cobbled together from various threads on SFT clones, these values seem to be close to expected - but I'm really not sure how close is good enough or what they suggest (or why). Still learning. Any help much appreciated - thanks!
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. Basically just went component by component checking values and continuity. Continuity was good on every single connection, but somewhere along the way when I was lifting legs to measure caps/resistors out of circuit I must have resolved an invisible bridge or something - I did a few components in each pass and lost track of what finally did it, but it was probably something late in the signal chain. Most likely something going to ground that shouldn't have or vice versa.
