# Phase II Problems



## Jovi Bon Kenobi (Jun 14, 2019)

Finished building this up and it is not producing any effect when activated. When activated and the indicator LED is on I just get my dry guitar signal. There is a very faint ticking sound relative to the rate potentiometers position if it's on or off.  As I do with every build, I audited every component for correct value before soldering. I recorded all the voltages on all IC's and the transistor with my DMM. I'll post them in a few minutes but here's the photos.

Oh, and the 2 things I did differently from the build doc is use a 5mm UV LED for the indicator (build doc says 3mm red, is that the fault?!) and also, I used an A50k for the rate because I don't have any A25K's.


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## Jovi Bon Kenobi (Jun 14, 2019)

Here are the voltages:

Voltage at DC jack: 8.7v

IC1:
1: 0.6mV  2: 0.9mV  3: 0.1mV  4: -7.39V  5: 0.1mV  6: 1.2mV  7: 1.3mV  8: 8.4V

IC2:
1: -6.7V  2: nothing  3: nothing  4: -7.39V  5: nothing  6: 2.5mV  7: 7.4mV  8: 8.4V

IC3:
1: 7.0mV  2: 3.2mV  3: nothing  4: -7.36V  5: nothing  6: 2.5mV  7: 4.4mV  8: 8.4V

IC4:
1: -0.5mV  2: -0.4mV  3: nothing  4: -7.35V  5: nothing  6: 4.9mV  7: 5.4mV  8: 8.4V

IC5:
1: 7.9V varies with depth/rate 2: -0.8mV varies with depth/rate 3: varies with depth/rate  4: -7.36V  5: nothing  6: 4.2mV  7: 6.0mV  8: 8.4V

IC6:
1: varies with depth/rate  2: nothing  3: varies with depth/rate  4: -7.37V  5: 0.1mV  6: 0.7mV  7: varies with depth/rate  8: 7.73V

IC7 (TC1044SCPA):
1: 8.4V  2: 5.06V  3: 0.5mV  4: -2.9V  5: -7.37V  6: 3.9V  7: 5.19V  8: 8.4V

Q1 (2N4401):
E: 7.6V varies with depth/rate B: 7.88V varies with depth/rate C: 8.4V


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## Jovi Bon Kenobi (Jun 14, 2019)

Also...D4, the yellow LED for LFO, never lights up.


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## Jovi Bon Kenobi (Jun 14, 2019)

Here is the link to the build doc


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## Nostradoomus (Jun 14, 2019)

For now I would reflow your switch soldering, looks pretty iffy. Also it’s hard to see but the LED should be flat side up. I have working Phasor II and duo phase builds I can check voltages on when I get home later. ?


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## chongmagic (Jun 14, 2019)

So the yellow LED is not coming on at all?

The voltages for the TL072s seem off.


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## Jovi Bon Kenobi (Jun 14, 2019)

Nostradoomus said:


> Also it’s hard to see but the LED should be flat side up


DOH! Thanks I'll switch it around.


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## Nostradoomus (Jun 14, 2019)

Sometimes it’s the simplest little thing, hopefully it works!


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## Jovi Bon Kenobi (Jun 14, 2019)

Nostradoomus said:


> hopefully it works!


It now lights up but I still have the same problem. I also reflowed the footswitch.


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## Jovi Bon Kenobi (Jun 14, 2019)

I remeasured the voltages and adjusted them above. its the red text.


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## zgrav (Jun 14, 2019)

you can't get any phasing without a variable light source.  you can play something through the pedal while shining a flashlight over the photoresistors if you want to see if the phasing circuit will respond.


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## Jovi Bon Kenobi (Jun 14, 2019)

Since swapping the polarity of the yellow LED it now lights up properly and adjusts like it should to the rate and depth pots, yet I still just get my regular guitar signal regardless of said LFO. No phaser sounds when engaged. I'm at work now for the next few hours but I'll be home after to troubleshoot more.


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## zgrav (Jun 14, 2019)

you should put together an audio probe to see if you can trace the sound as it goes through the parts of the phasing circuit.  you can do a google search for some simple build instructions and how to use it.


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## Jovi Bon Kenobi (Jun 14, 2019)

Good idea. That'll be next.


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## Nostradoomus (Jun 15, 2019)

Something is funky around your transistor, just measured mine (knobs set at zero) and I’m getting

C 8.8v
B 4.2
E 3.6v

Try reflowing your solder points on components surrounding it and anything relating to grounding. This problem sounds like a cold joint somewhere.


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## Jovi Bon Kenobi (Jun 15, 2019)

I appreciate everyone's help but I'm at a loss. I made an audio probe but I don't know enough about circuit order to properly use it. I reflowed a bunch of points around the PCB that looked spotty. I changed out all the socketed components for new ones. With the probe I was getting a sort of broken phaser sound on a couple of points, pin 6 of IC3, only one of the photoresistors legs, etc...

Sorry for your trouble.


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## zgrav (Jun 15, 2019)

no need to apologize to anyone for what you don't know about getting your pedal to work.   you're doing about the best you can flying blind.  but it is very tough to troubleshoot a circuit without being able to compare what you have on the board with how things are supposed to fit together on the circuit diagram.  

as noted above, you should check connections of your parts to the PCB (and to each other as shown in the circuit board) around the transistor where Nostradoomus is getting different readings on his build of the pedal.

and track down a few more articles and watch some youtube videos on how to use the audio probe.  do the same thing for looking up how to use your DMM.  that material is there, and most us have had to plow through it one way or another along the way.


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## Jovi Bon Kenobi (Jun 15, 2019)

Thanks z. Yeah I need to just step back a bit and re-approach this with more knowledge under my belt. I really do appreciate the support.


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## Nostradoomus (Jun 16, 2019)

Oh yeah it’s no trouble. I love this stuff and am happy to help.

I’m still basically at the same spot you are, I can not follow a signal path with a probe to save my life. I do know that if you audited all of your components for faults beforehand and use decent quality parts, the most likely thing is a bad solder joint, switch, pots or something off board. I was recently tearing my hair out when every build I had in the pile didn’t work (weak unaffected signal etc)...it was the switch on my test box (which I cannot suggest as your next build enough!)

Put it aside and take on something easier, there’s no shame there. Good luck!


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## zgrav (Jun 16, 2019)

Maybe look at a working pedal you have built and the circuit diagram for it, and use your audio probe to learn how to follow the signal through it to get some practice.  Then you will have more experience using it to find where something stops working when you are troubleshooting.


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## Jovi Bon Kenobi (Jun 14, 2019)

Finished building this up and it is not producing any effect when activated. When activated and the indicator LED is on I just get my dry guitar signal. There is a very faint ticking sound relative to the rate potentiometers position if it's on or off.  As I do with every build, I audited every component for correct value before soldering. I recorded all the voltages on all IC's and the transistor with my DMM. I'll post them in a few minutes but here's the photos.

Oh, and the 2 things I did differently from the build doc is use a 5mm UV LED for the indicator (build doc says 3mm red, is that the fault?!) and also, I used an A50k for the rate because I don't have any A25K's.


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## zgrav (Jun 16, 2019)

this article is a great explanation of how the univibe pedal works (a pedal that has a lot in common with your phaser pedal).  you may get lost in it pretty quickly if you try to go through all of it at once,  but you can bookmark it and focus on a little bit at a time.  it explains what the photoresistors do in the circuit and how the LFO (low frequency oscillator)  works.   it also sort of walks you through what happens in the circuit, which is useful for knowing where to check things with an audio probe.


			Frames for The Technology of the Univibe


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## Jbanks (Jun 20, 2019)

zgrav said:


> Maybe look at a working pedal you have built and the circuit diagram for it, and use your audio probe to learn how to follow the signal through it to get some practice.  Then you will have more experience using it to find where something stops working when you are troubleshooting.


I learned to use a audio probe on a really really basic fuzz with about 7 components. You can start touching the probe to the input and output jacks to get a feel of how it works. Just start at the Input jack on the schematic and start following from component to component. On a simple fuzz, it’s straight line without a lot of complications. Once you get the hang the probe, you can begin to trace out more complicated schematics. But it’s a really strong way to follow your signal path and learn how the components add and take away gain/volume/tone etc. if you find a spot with no signal, that’s the problem component. 

I always have a looper pedal playing a riff into the pedal so it can just always be sending input signal to the PCB. 

But the probes pretty easy to make and is definitely your best tool (besides a DMM) at troubleshooting PCB’s. 

Good luck!


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