SOLVED XC phase not phasing

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Grazza

Active member
Just finished this pedal but there is no phasing. Definitely sound, and there is a sound difference when the switches are flicked but no phase.
I just read another post with the same problem but I'd love some eyes on it in case I missed something else. Here's what I've tried:
Started with matched quad of 2n5457s and a 2p200 instead of the 2n4125. Turned the 5457s around in case they needed to be the other way and nothing. Swapped the 2p200 for a 2n3906, nothing.
Swapped the 2n5457s for 2 matched pairs of the right transistors in as the silk screen says with the 3906. Nothing. Swapped the TLO22 for another and changed out the TLo72s. Nothing.
Will try everything again and maybe I haven't turned the trimpot slow enough.
Is there anything else I'm missing or doing wrong?
 

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Ok, switches have continuity so they aren't the problem, when I get a bit of time I will learn how to use the audio probe properly. Hopefully over the weekend
 
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Hi, bringing back an older one... I'm starting to play with the audio probe. I have sound on every resistor, up to R13. Then going forwards R13,14,15,16, 17 have no sound on them no matter which way the switch is oriented. I have sound on R27 no matter which way the switches are oriented. I have sound on R19 too. The PCB is still in the enclosure so i can't get to the caps, need the underside for that and I'll get it out again to test them. Problem is, I don't really know what this means...
 
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Your audio probing sounds pretty positive. I have highlighted what I understand the audio path to be. You should have audio when you touch all of these spots (although it may depend oh switch position).

I have circled the stages switch ads you said one of these positions produces no sound. I would check for audio on both sides of the stages switch. it will be that the middle position has audio and one of the other sides. Then when you flick the switch it will be the middle and the other side. this is how it shoudl work however I think a connecition may be broken in yours.

If a connection is broken (as in audio on one side of the switch but not the other), I would then check there is audio along my orange lines in the image. If there is audio along the orange lines but not in the switch then you know the link is broken and need to solde a wire between bot of these points.

Screenshot 2025-06-08 at 7.55.14 PM.png
 
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See this pic below.

I may have this backwards, but the parts circled with the same colour should be connected.

If you have audio on one side of the stages switch but not the other, I assume the problem is here.

Use a multimeter to touch both purple parts to check connectivity and the same with yellow. Although I may have it backward and purple IC3 pin 1 might be the yellow side of the stages switch. But the point is that the circled parts of the two Ics should be connected to one of the circled points on the stages switch (you will have to flick the switch).

Screenshot 2025-06-08 at 8.12.55 PM.png
 
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Thank you I will check. When I was probing earlier, I'm sure I tried the switch in both positions and in both positions of the switch there was no sound in all of the resistors from R13 to R17. This didn't make a lot of sense to me as I thought it would work in one position not the other. I will do this again using your diagram to confirm and I'll check those points with the DMM.
Thanks, I'll let you know how I go
 
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No problem at all. I am pretty sloppy with my builds so as as result I have done a lot of trouble shooting and have started to get pretty good at it (out of necessity).

If you are getting phasing then you must be getting audio on r16 and R17. Try again. If you don't have audio on r14 then that is a big clue. If that's the case I would check continuity around this area (i.e. r14 is connected to IC1 pin 6 and 7, IC1 pin 5 connected to r13, IC1 pin 5 is connected to source Q4, c5, r15.

I find it is helpful to print the schematic, I then highlight where I have audio in yellow (or any colour really) and draw in a pen where there is connection. if you find 2 points that are not connected but should be per the schematic you know you have found the issue.

If you encounter a place where there is no audio, you can investigate that area more thorougly. You should get audio everywhere that I highlighted.
 
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I have continuity in all of the above areas. IC 1 pin 7 has continuity to stages switch when switched on way, but not the other. Is this correct? It has continuity with the script switch on both sides of the switch
 
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I am doing some probing. I have audio on pin 6 IC 2, but no audio on R13 and R14. I have audio on R16 when the stages switch is in one orientation and not the other. I have audio up until R13. I have audio on R17, R27. I haven't checked capacitors because they are under the board and it is in the box. Do I have a problem with R13 or R14 or the connection between them? I also have no audio on Pin 7 IC 2. Shoud I?
 
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Grazza said:
I am doing some probing. I have audio on pin 6 IC 2, but no audio on R13 and R14. I have audio on R16 when the stages switch is in one orientation and not the other. I have audio up until R13. I have audio on R17, R27. I haven't checked capacitors because they are under the board and it is in the box. Do I have a problem with R13 or R14 or the connection between them? I also have no audio on Pin 7 IC 2. Shoud I?
Click to expand...
Every place you mentioned should have audio. The problem must be around ic2 because yes you shoukd have audio on pin 7 of ic2.

The problem must be around here. I assume you have audio on pin6 ic2?

I’d do the following
  • Take it out of the box to make it easy.
  • Check voltage on ic2. You want 9v on 8, 0v on 4 and 4.5v on the rest. Maybe post the voltages here.
  • Check continuity around ic2.2. C4, r10, r11, r12. Make sure all of the points are connected.
It seems odd to me that you have audio on r13 but not ic2 pin7 as these are connected or should be.
 
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I thought I had swapped out the ICS, I'll try again. I have no audio at R13 and r14 and no audio at pin 7. I will pull it out of the box and investigate again. I feel like I'm getting closer
 
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Grazza said:
I thought I had swapped out the ICS, I'll try again. I have no audio at R13 and r14 and no audio at pin 7. I will pull it out of the box and investigate again. I feel like I'm getting closer
Click to expand...
Definitely. You have found the spot where the audio stops. Now just to explore the area to see why
 
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