peccary
Well-known member
Hey everyone,
I'm having some trouble with this build and I'm hoping someone can point me in the right direction. Here's the build docs.
The pedal works well in Wah mode and Synth 1, but on Synth 2 I am getting very low volume as well as some scratchiness.
I went through and measured the voltages and was getting some wacky readings on the voltage regulator as well as a few pins on the LM 13700. I also adjusted the trim pot to the correct 7 volts.
On the regulator I'm getting I - 9.33 (fine) O - 7 (fine) and on the ground I am getting 5.76. I don't know what's going on with the ground because according to the docs it ought to be at 0, so this one is weirding me out.
On the LM 13700 most values are pretty close but there are a few that are pretty far out of whack: 1 reads 0.96 (should be 1.12), 5 reads 2.19 (should be 5.9), 7 reads 2.18 (should be 5.9), 10 reads 2.02 (should be 5.82), and 12 reads 2.07 (should be 5.83), 16 is 0.96 (should be 1.15).
I'm hoping that this is a bad regulator or chip that I can replace and that someone can tell me that based off this information, but if I need photos of the I can grab some. The 4558's and transistors all align somewhat well with the reported necessary voltages, though there is some variance. the ones I listed above were way off. I haven't had a chance to go through it with my probe yet, but I won't have time for that for a few days, at least, so I thought it couldn't hurt to ask here. It seems odd to me that it would work perfectly in two of the three modes, or at least that makes me think that it's something specific and that someone might be able to point to something based off this info.
Here's a photo of all of the values I got written out on the build docs that list the correct voltages if that's helpful:
photos.app.goo.gl
Thanks for your help, folks. I really appreciate it.
I'm having some trouble with this build and I'm hoping someone can point me in the right direction. Here's the build docs.
The pedal works well in Wah mode and Synth 1, but on Synth 2 I am getting very low volume as well as some scratchiness.
I went through and measured the voltages and was getting some wacky readings on the voltage regulator as well as a few pins on the LM 13700. I also adjusted the trim pot to the correct 7 volts.
On the regulator I'm getting I - 9.33 (fine) O - 7 (fine) and on the ground I am getting 5.76. I don't know what's going on with the ground because according to the docs it ought to be at 0, so this one is weirding me out.
On the LM 13700 most values are pretty close but there are a few that are pretty far out of whack: 1 reads 0.96 (should be 1.12), 5 reads 2.19 (should be 5.9), 7 reads 2.18 (should be 5.9), 10 reads 2.02 (should be 5.82), and 12 reads 2.07 (should be 5.83), 16 is 0.96 (should be 1.15).
I'm hoping that this is a bad regulator or chip that I can replace and that someone can tell me that based off this information, but if I need photos of the I can grab some. The 4558's and transistors all align somewhat well with the reported necessary voltages, though there is some variance. the ones I listed above were way off. I haven't had a chance to go through it with my probe yet, but I won't have time for that for a few days, at least, so I thought it couldn't hurt to ask here. It seems odd to me that it would work perfectly in two of the three modes, or at least that makes me think that it's something specific and that someone might be able to point to something based off this info.
Here's a photo of all of the values I got written out on the build docs that list the correct voltages if that's helpful:
New item by Joe B
photos.app.goo.gl
Thanks for your help, folks. I really appreciate it.
.
