Bypass when on, mute when off

MacGuffin_

MacGuffin_

Member
Honestly, not even sure how I got here.

Building abyss, when I turn on the switch (LED on) I get a clean signal. When I turn it off, I get nothing. Can I get a sanity check with my wiring? I am using this 3pdt board [Link].

I already tried removing the modded LED, no luck. Yellow is jack in, blue jack out. red is board in below and black board out. red (+), black (-) up top, and green is always ground.


PXL_20230529_021517228.jpg
 
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MacGuffin_ said:
074:
4.5 [ ] 4.5
4.5 [ ] 4.5
4.5 [ ] 4.5
9.0 [ ] 0.0
4.5 [ ] 4.5
4.5 [ ] 4.5
4.5 [ ] 4.5

072:
4.5 [ ] 9.0
4.5 [ ] 4.5
4.0 [ ] 4.5
0.0 [ ] 4.5
Click to expand...
Those all look normal. I’d try an audio probe at this point. See where you are losing signal. Actually the 4.0 on the 72 looks a bit odd I’d expect pin 3 to be 4.5 there as well. That’s right at the beginning of the circuit so the audio probe will tell you pretty quick. If that’s the problem. I would probe pin one of the 72 first if no signal go backwards from there.
 
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Locrian99 said:
My experience with this circuit is that doesn’t matter. Mine worked in a normally lit room wirb the cover off.
Click to expand...
I didn't look at the circuit in details, but saw the LDR, if they are Resistance when dark (or probably even the opposite), how could there be an effect when the LDR catches light ?

My thinking is, in his description he has 2 problems. No effect when pedal is turned on (Could be caused by testing in the ambient light), no bypass (a different problem)....
 
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EGRENIER said:
I didn't look at the circuit in details, but saw the LDR, if they are Resistance when dark (or probably even the opposite), how could there be an effect when the LDR catches light ?

My thinking is, in his description he has 2 problems. No effect when pedal is turned on (Could be caused by testing in the ambient light), no bypass (a different problem)....
Click to expand...
I thought he had signal in bypass and no signal when engaged… I could’ve misread. By any means this circuit does not need darkness to have an effect. I literally tested mine in normal lighting not in an enclosure hooked up through a test box. And the effect worked fine. I understand the thought and lots of people say that but this one did not need total darkness to work in my experience.

Also ldrs take time to drop all the way down to their max resistance. So I’m assuming the brightness of the light by its proximity to the Ldr is why it doesn’t matter. The brightness of light 8ft away and without the light pointed directly at the Ldr is going to be far less than millimeters and points straight at it. At least that’s why I think this one works.
 
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Sorry I didn't read all the replies. Do you have your jacks connected correctly? If you don't, you won't get jack shit. Those switching jacks can be annoying to hook up correctly if you're not being deliberate
 
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Locrian99 said:
I thought he had signal in bypass and no signal when engaged… I could’ve misread. By any means this circuit does not need darkness to have an effect. I literally tested mine in normal lighting not in an enclosure hooked up through a test box. And the effect worked fine. I understand the thought and lots of people say that but this one did not need total darkness to work in my experience.
Click to expand...
Hmmm when I read this:

MacGuffin_ said:
Building abyss, when I turn on the switch (LED on) I get a clean signal. When I turn it off, I get nothing.
Click to expand...

I understood "turn on the switch" as effects on and "I turn it off" as in bypass....

As for the LDR, I looked them up and they provide 500K when dark and 10 to 20K at 10 lux. 10 lux is not a lot, so unless yours were snug enough to the LED to dim the light under 10 lux and stop it getting caught by the photo censor, in theory at ambient light the resistance will never go up...
 
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EGRENIER said:
Hmmm when I read this:



I understood "turn on the switch" as effects on and "I turn it off" as in bypass....

As for the LDR, I looked them up and they provide 500K when dark and 10 to 20K at 10 lux. 10 lux is not a lot, so unless yours were snug enough to the LED to dim the light under 10 lux and stop it getting caught by the photo censor, in theory at ambient light the resistance will never go up...
Click to expand...
It wouldn’t hurt I guess. I stopped worrying about it when I was told by someone else it didn’t matter with this circuit. Idk I’m just telling you my experience with this and it worked fine for me.
 
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EGRENIER said:
Hmmm when I read this:



I understood "turn on the switch" as effects on and "I turn it off" as in bypass....

As for the LDR, I looked them up and they provide 500K when dark and 10 to 20K at 10 lux. 10 lux is not a lot, so unless yours were snug enough to the LED to dim the light under 10 lux and stop it getting caught by the photo censor, in theory at ambient light the resistance will never go up...
Click to expand...
I had the LED wired to the wrong pin at the start, so it looked reversed to me. I get bypass, but absolutely no signal when engaged (box closed up or not)
 
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MacGuffin_ said:
After probing around more, I have 4.5v up until the A100k pot. somewhere between the 56k resistor and the pot I lose all voltage
Click to expand...
OK so bypass works and when you engage you have no sound...

Does D2 blinks ? If you don't get any light on D2 I think you need focus on this part of the circuit first. You should also get an audio probe to trace the signal from input to each stages...

1685397256998.png
I would check the voltage on Q1 and Q2...

From what I have found in other thread, your voltage should be:

Q1 (MPSA18)
C=1.90-1.92V
B=0.61V
E=0.00V

Q2 (MPSA18)
C=1.91-2.02V
B=0.66V
E=0.05V
 
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EGRENIER said:
OK so bypass works and when you engage you have no sound...

Does D2 blinks ? If you don't get any light on D2 I think you need focus on this part of the circuit first. You should also get an audio probe to trace the signal from input to each stages...

View attachment 49458
I would check the voltage on Q1 and Q2...

From what I have found in other thread, your voltage should be:

Q1 (MPSA18)
C=1.90-1.92V
B=0.61V
E=0.00V

Q2 (MPSA18)
C=1.91-2.02V
B=0.66V
E=0.05V
Click to expand...
D2 works flawlessly, I do need to buy a audio probe...
 
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MacGuffin_ said:
Built one, used my synth as input. It gets signal up to the A100k, left lug works fine, no signal out of the right or middle. and that is no signal from the lugs themselves, not the solder point. Just a bad pot?
Click to expand...
left lug in presuming you are looking at the component side that is lug 3. Do you have a pot condom on it? Are you hearing the effect at lug 3. That is literally the last point in the circuit.
 
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MacGuffin_ said:
Sorry, left lug looking at the bottom up (as if mounted in the box), should be lug 1?
Click to expand...
Maybe try re-flowing all the lugs of the top-middle pot? It's hard to tell on my screen, but that middle lug looks like it could use a little bit more solder.

EDIT: Same with the left lug / Lug 1 of the A100k (looking at your most recent photo).
 
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