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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The trimpot has a very small spot around the muddle where the effect works.

Have you got a multimeter? If so what is the voltage on pin 7 of ic3? Does it go up and down?
 
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Yes the voltage goes crazy then back to zero. I just had another go of the trimpot and I turned it very slowly, still nothing. Will give it another go
 
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I measured the voltage again, maybe I made a mistake last time, it's a pretty consistent 4.2v. does it matter that it is a matched pair of transistors? Should I switch back to the matched pair of 2n5457s?
 
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Sorry what transistors are you using? This should work with 4 x 2n5457. Mine does.

When you say consistent voltage of 4.2v do you mean on pin 7 of ic3? If so that tells me that your lfo isn’t working so it won’t really phase

Can you write the voltage of each pin of ic3 here?
 
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I was using 2n5952s, don't think they are matched very well, I've just matched some 2n5457s as best I can, I had about 25 to choose from.
I checked pin 7 of IC3 which I think is the top one (TLO22) looking at the PCB. Will get the 5457s in and take some readings.
 
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Grazza said:
I was using 2n5952s, don't think they are matched very well, I've just matched some 2n5457s as best I can, I had about 25 to choose from.
I checked pin 7 of IC3 which I think is the top one (TLO22) looking at the PCB. Will get the 5457s in and take some readings.
Click to expand...
IC3 is the top one. Pin 7 should go up and down in voltage depending on where the rate pot is set.
 
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Very good eyes, that is in fact a 3k9 instead of a 3m9, the mistakes are usually small and silly with this sort of thing. Won't have time to change it now, will do it tonight.

2n5457s are in and matched as closely as I have stock for. It is phasing, I expected the effect to be stronger maybe. Forgot to take those pin readings before I started to pull it apart, will do that tonight. I feel like the effect could be better
 
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Grazza said:
Very good eyes, that is in fact a 3k9 instead of a 3m9, the mistakes are usually small and silly with this sort of thing. Won't have time to change it now, will do it tonight.

2n5457s are in and matched as closely as I have stock for. It is phasing, I expected the effect to be stronger maybe. Forgot to take those pin readings before I started to pull it apart, will do that tonight. I feel like the effect could be better
Click to expand...
It’s a phase 90, it should at least sound like that. May have more than one issue.
 
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Ok, resistor replaced, phaser now phases and sounds how it should, I'm happy with that. However, when flicking the stage switch to the left, there is no sound at all. Works to the right, doesn't do anything to the left.
 
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Good to hear it’s working.

It sounds like maybe your switch isn’t working properly.

One end of the switch is connected to Pin1 of ic3 (top) and the other is connected to pin7 of ic2(middle).

If you have an audio probe I would also check that you have audio on these points.

Maybe check with a multimeter that these points are connected to the middle pin of the stages switch when you flick it to each side.
 
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Ok I'll check those things, weird thing is it was fine before I changed the 3m9 resistor. I did make an audio probe recently still working out how to use it...
 
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Grazza said:
Ok I'll check those things, weird thing is it was fine before I changed the 3m9 resistor. I did make an audio probe recently still working out how to use it...
Click to expand...
I use a spare audio jack connected to a lead going to the amp. The jack sleeve should be grounded (i use an alligator clip to connect it to ground on the PCB). The tip is connected to a 100nf capacitor (soldered or alligator clipped) which can be connected to another wire (or you can use the leg of the capacitor).

You just touch areas of the circuit with the cap leg or the wire connected to it with the amp turned on. You can either strum the guitar or play a looper pedal to get audio. The pedal should be on with audio going into the input.

If you hear audio on pin1 of ic3 (which you should) but not on the switch then that is a good indication that the switch is the problem.
 
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Grazza said:
Great info. Yes, the resistor just didn't want to come out! What happens if the Trace is broken? Does that mean I just live with the switch not working?
Click to expand...
You can just solder a piece of wire from the switch to where it should be connected.

Check with a multimeter and/or audio probe to see if they are connected. If not some wire should do the trick.
 
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Grazza said:
Great info. Yes, the resistor just didn't want to come out! What happens if the Trace is broken? Does that mean I just live with the switch not working?
Click to expand...
Hot tip, these are great for removing parts.

Also if you have a piece of metal you can gently lever one end of a resistor, and then apply heat to one of the pads. Once the pad heats up, the pressure of your lever should lift the resistor without damaging the pad. Then you can grab plies and pull the other end out with the same method...but be gentle
 
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