Hi all,
Quick intro: I'm a relatively new builder but have a dozen or so successful projects by now. I can make sense of schematics/circuits and whenever I've encountered an issue so far, I was able to troubleshoot it myself. But here's one that's got me scratching my head for a day.
I built the Taqueria kit and everything went (mostly) smooth. When biasing the JFETs, I have a strange reading on the second transistor. I can bias the first and third one to the recommended values (on both positions of the switch). The voltage at transistor 2 reads ~17.5v (which is the voltage being put out by the power section) but when I try to bias it, I can only budge the voltage a ~0.3V up or down (on both positions). I tried swapping transistors, looking for solder bridges... the usual. No luck.
Any ideas? At first I thought it might be a faulty trimpot, but it would be extremely unlikely that both trimpots at this position would happen to be equally faulty. I also don't understand why I can adjust the voltage (which would mean it is going through the trimpot), but only by such a minimal margin. Since the power is coming from the same path for all 3 JFETs (pre switch/bias trimpot), I am out of ideas on what to check next. Could anyone pitch in here? I've circled the problem section on the schematic below.
Thank you so much in advance!
Quick intro: I'm a relatively new builder but have a dozen or so successful projects by now. I can make sense of schematics/circuits and whenever I've encountered an issue so far, I was able to troubleshoot it myself. But here's one that's got me scratching my head for a day.
I built the Taqueria kit and everything went (mostly) smooth. When biasing the JFETs, I have a strange reading on the second transistor. I can bias the first and third one to the recommended values (on both positions of the switch). The voltage at transistor 2 reads ~17.5v (which is the voltage being put out by the power section) but when I try to bias it, I can only budge the voltage a ~0.3V up or down (on both positions). I tried swapping transistors, looking for solder bridges... the usual. No luck.
Any ideas? At first I thought it might be a faulty trimpot, but it would be extremely unlikely that both trimpots at this position would happen to be equally faulty. I also don't understand why I can adjust the voltage (which would mean it is going through the trimpot), but only by such a minimal margin. Since the power is coming from the same path for all 3 JFETs (pre switch/bias trimpot), I am out of ideas on what to check next. Could anyone pitch in here? I've circled the problem section on the schematic below.
Thank you so much in advance!
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