No output when in bypass

[Kkunited]

I just built a fuzz pedal, but I encountered a problem when testing it, after I installed it in the enclosure.

When in bypass mode, it does not output any sound. it is dead silent, but when I engage the pedal, it partially works, giving me a weak fuzzy effect. However, it makes a bright loud noise, and the volume of this noise seems to be controlled by the treble knob. Funny enough, the noise also appears when in bypass mode if I turn the treble up, which I find quite strange. After all, I thought the bypass mode would bypass the PCB, and would not be affected by any of the knobs.

Does anyone know what could be causing this issue?

This is the pedal I made: https://guitarpcb.com/wp-content/uploads/2018/05/BD_4-Track-Fuzz.pdf

[GibsonGM]

Go back over all of your switch connections...make sure you are looking at the switch terminals the right way (and are not off by 90 degrees or something...).     

Did it work OUTSIDE of the enclosure?  If so, something could be grounding to the enclosure and need to be moved.

Might help to remove all the guts and see if it works ok outside the enclosure...I always test PCBs with jacks connected by jumpers before even adding the switch, to assure it is ok - then any problems will be from switch connections.

You'll get it working, keep at it!   Welcome to the forum...

[DIY Bass]

Bypass mode should be bypassing the PCB. That is probably the first thing to get working, as it is the simplest circuit. Once you have bypass working then see what has happened to the effect tone.  Firstly, did you test it before you put it into the enclosure?  That is often a good plan.  If you did, and it worked and now it doesn't, you have almost certainly shorted something to the enclosure, which should be grounded.  Test the signal path with a multimeter to see if there in connectivity to the case.  If that is fine, then I would test the connectivity of the input jack top the output jack, with the switch set to bypass.  If your signal is not connected to the enclosure, and it is silent in bypass, then there is probably no connection between the input jack and the output jack.  Keep testing back through the chain until you get a connection (test the input jack to the output side of the switch, then to the link between the switch sides, then to the input side of the switch etc)  Somewhere you will find a connection, and that will tell you where the problem is.  Then look for poor solder joints or other problems and fix what you find.

[Kkunited]

Bypass mode should be bypassing the PCB. That is probably the first thing to get working, as it is the simplest circuit. Once you have bypass working then see what has happened to the effect tone.  Firstly, did you test it before you put it into the enclosure?  That is often a good plan.  If you did, and it worked and now it doesn't, you have almost certainly shorted something to the enclosure, which should be grounded.  Test the signal path with a multimeter to see if there in connectivity to the case.  If that is fine, then I would test the connectivity of the input jack top the output jack, with the switch set to bypass.  If your signal is not connected to the enclosure, and it is silent in bypass, then there is probably no connection between the input jack and the output jack.  Keep testing back through the chain until you get a connection (test the input jack to the output side of the switch, then to the link between the switch sides, then to the input side of the switch etc)  Somewhere you will find a connection, and that will tell you where the problem is.  Then look for poor solder joints or other problems and fix what you find.

Thanks for answer,

Unfirtunately i did not test it outside the enclisure. As a beginner i do not know how to test this particular PCB with a stereo input jack. I wil try to make bypass work, and if the effect does not work at that point (assuming that i have checked that it is not toucing the enclosure) i think it is safe to conclude that the pcb is not working.

[Marcos - Munky]

Remove the circuit from the enclosure and test it. Also, post pics of your build, it help us a lot to help you when we can see what you did.

[Kkunited]

Remove the circuit from the enclosure and test it. Also, post pics of your build, it help us a lot to help you when we can see what you did.

I have now tried it with the pcb outside the enclosure, but it still reacts in the same way unfortnately.

Btw, here is a pic from inside the enclosure, i know it looks tight, but i am pretty sure that nothing is shorting or anything, at least i have not found any shorts.

[thermionix]

Any reason you have a stereo plug in the output jack?

[bluebunny]

Where does that white wire coming off the DC jack go to?  I can only see one end of it.  For that matter, where do each of the red wires go?  The one on the leftmost lug (which snakes around to the right) is intended for attaching a battery clip, but I see no battery (or clip).

[Kkunited]

Where does that white wire coming off the DC jack go to?  I can only see one end of it.  For that matter, where do each of the red wires go?  The one on the leftmost lug (which snakes around to the right) is intended for attaching a battery clip, but I see no battery (or clip).

The white wire from the DC jack goes to ground on the PCB, the lower lug goes to 9v on the PCB, and the left lug goes to the battery clip. If you open the picture, you can see the battery clip behind the DC jack just taped over so that the clip wont touch anything, as i do not intend to use a battery.  (i dont think the tape should cause any issues).

[bluebunny]

OK, that's fair enough.  I couldn't see the battery clip.  Good disguise job!      So long as you have continuity amongst all your ground connections - including the white wire from the DC jack - then that's me done for now...

(BTW, you could simply have omitted the battery clip.  If you intend ever un-taping it and using it, normal practice would be to take that white wire to the ring connection of [usually] your stereo input jack, so that the battery is disconnected when no jack is inserted.)

[Hemmel]

Hi Kk,

These might seem like weird questions but it's hard to see from just one picture.
   - On top-right of the 3PDT, there seems to be a rogue strand that might short-out pins top-right and middle-right. It might be light reflecting on flux, though.
   - Same thing between pins middle-left and bottom-left
   - You didn't put a resistor in R14, and unless there's a hidden resistor behind the PCB (there seems to be something soldered on the other side), that's bad for your LED
   - Make sure you haven't switched the IN pads (top and bottom) or OUT pads on the PCB. Top pad is for signal and bottom pad is for ground. Commonly we would use different colored wiring for both. Since you used same color wiring (blue for input and green for output), then it's hard to see what goes where. Mixing these might be the cause of no sound when in bypass.

[Kkunited]

Hi Kk,

These might seem like weird questions but it's hard to see from just one picture.
   - On top-right of the 3PDT, there seems to be a rogue strand that might short-out pins top-right and middle-right. It might be light reflecting on flux, though.
   - Same thing between pins middle-left and bottom-left
   - You didn't put a resistor in R14, and unless there's a hidden resistor behind the PCB (there seems to be something soldered on the other side), that's bad for your LED
   - Make sure you haven't switched the IN pads (top and bottom) or OUT pads on the PCB. Top pad is for signal and bottom pad is for ground. Commonly we would use different colored wiring for both. Since you used same color wiring (blue for input and green for output), then it's hard to see what goes where. Mixing these might be the cause of no sound when in bypass.

Unfortunately all the points you are asking about seems to be connected properly, but just one question: what do you mean by «rogue strand»?

And why does soldering R14 on the other side damage the PCB?

What i just don't get, is that the path from input to output is so darn simple, so i am just freaking out because it all looks to be soldered right. Unless  that «rogue strand» you are mentioning is the thing causing this all to fail.

[Hemmel]

The "rogue strand" would be a very small metal fiber coming out of a wire and not soldered to anything, being free to move and touch any other wire/component and thus causing a short circuit. But, as I said, on your picture it might be the light reflecting on some flux. It's hard to say.
But I would check for connectivity between 3PDT lugs top-right and middle-right, then hit the switch and check connectivity again. Those 2 lugs should connect/disconnect by flipping the switch.

I didn't say the R14 on the other side would damage the PCB. I said that if it's not there (you just confirmed that it is soldered behind), then that is bad for the LED.
That's no longer a problem since it is confirmed that R14 is present, whatever side of the PCB it is on.

[Hemmel]

What i just don't get, is that the path from input to output is so darn simple, so i am just freaking out because it all looks to be soldered right. Unless  that «rogue strand» you are mentioning is the thing causing this all to fail.

I would try connecting 2 trust-worthy guitar cables in input and output, then checking connectivity between the tips of these cables. If there's no connectivity, then hit the 3PDT switch (no need for the pedal to be powered for this test). If there's still no connectivity between the cable tips, then the issue is either with the internal wiring or maybe even the 3PDT switch itself.

[Kkunited]

Thanks a lot for the tips! I really appreciate the help trying to solve something that can only be described as a mystery. I will buy a multimeter, and will post the results tomorrow!

Let's get a closure:)

[Hemmel]

Good idea to get a multimeter.
It depends on your budget, of course, but don't get a cheap one. Get one that will last a good while, it's a good investment.
I use mine all around the house!

Keep us posted with your findings!

[thermionix]

The IN and OUT on the board...those are laid out for shielded wire, right?  Looks like two blue unshielded wires at the IN and two green unshielded wires at the OUT.  If you're not using shielded wire, there's no point hooking a superfluous ground wire up in place of the shield.  Can't tell if either pair is swapped, like maybe OUT hot is going to ground at the output jack.

Or I could be seeing it wrong.

[Kkunited]

The IN and OUT on the board...those are laid out for shielded wire, right?  Looks like two blue unshielded wires at the IN and two green unshielded wires at the OUT.  If you're not using shielded wire, there's no point hooking a superfluous ground wire up in place of the shield.  Can't tell if either pair is swapped, like maybe OUT hot is going to ground at the output jack.

Or I could be seeing it wrong.

I bought this guitar pedal as a kit, and all the wires were the same just different colors, so i would assume that they do the job just fine?

[Hemmel]

If it came as a kit, then yes, I would assume all the wires are fine.
Can you verify that you haven't inverted wires on input and output connections?
Top-left pad of 3PDT should go to top pad of "IN" on PCB, while sleeve from input jack goes to bottom pad of "IN" on PCB.
Top-right pad of 3PDT should go to top pad of "OUT" on PCB, while sleeve from output jack goes to bottom pad of "OUT" on PCB.

[Kkunited]

Hi folks!

I bought me a multimeter and used the continuity mode to check every connection in the true bypass path, just to confirm that it is all connected together.

And then...

After some testing i noticed something wierd:

The bottom right lug on the 3PDT swich was not connected to the bottom left lug, something that i found quite strange, being that there is a jumping wire connecting the two. So, i tried to use an alligator clip between the lugs and all of a sudden there was a connection between the lugs on the meter. I resoldered both lugs, and what do you know? The pedal outputted a clean-noisefree signal, and now i could finally hear my beautiful '65 jazzmaster pickups!

Unfortunately I do not have a power supply right now, so i could only test it in bypass and not with the effect engaged, but after all, the true bypass was what i had problems with.

To all of you that have posted on this thread: thank you for helping me, but also others who may encounter a similar problem in the future. I will report tomorrow if the pedal works when engaged:)