ROG Uno help

[freshmex18]

I should probably be more clear about what I wrote earlier.  When i said I hear a whining noise, I meant I ONLY hear a whining noise.  There is no guitar signal output.  So it isn't like a high gain pedal that needs a shielded input wire to quiet the background whining noise like my Diezel VH4 pedal did.

I am still new to this hobby and have a very limited understanding of how circuits actually work as should be evident by my lack of understanding previous comments.  I can basically plug and play components into a vero layout but I only partially somewhat understand how a circuit actually works.  As such, I will frequently need clarifying information so I can follow along.

So by saying "temporarily ground the PCB input" you mean I take the input wire, add it to the ground clip of the test box along with the ground wires, and then play with the pedal knobs to see if there is any change in the whining and also use the MM to recheck the J201 voltages and make any necessary adjustments, correct?

[anotherjim]

Yes. Ground anywhere in the input signal feed path.
I'm not saying you have a feedback problem, but it's worth checking. When a circuit oscillates due to positive feedback, it can be a very high frequency and a spikey waveform that can block audio frequency in the transistors. Without an oscilloscope that would show that waveform, we have to look for other clues that point to it.
Then it's back to an audio probe to follow a signal through stage by stage from the input as already suggested.

[idy]

So the signal comes out of Q1. Is it louder than when it went in? Does it change when you adjust the trimmer for Q1? About Q2, it goes in strong and come out weak. Does adjusting Q2 trimmer change anything? It should be strong enough to give overdrive out of Q2.

These "FETs with trimmers" circuits produce nothing unless the trimmer is in the right range, and you adjust by ear for a sweet spot which is not always mid voltage on the drain.

If you lose sound after the treble cap that suggests (either a bad solder joint or a )solder bridge shorting the signal out right there, in that "tone stack" of the three pots and three caps. Power off, test for a short (continuity to ground) from the leg of the Cap that goes to the treble pot.

Remember bad solder joints don't always look bad.

Also, with some "fender-ish" tone stacks, when all the knobs are on zero, nothing comes through at all. Make sure B, M, T are on at least halfway before deciding its broken!

[antonis]

Have you double-checked items values..??
(e.g. 1k instead of 1M Q3 Gate bias resistor could easily result into practically no signal..)

[freshmex18]

Grounded the input wire and the biases for all four resistors did not change.  Still reading at ~4.5.  Playing with the knobs did not do anything to change the sound coming out of the amp.

I have checked and rechecked every component value and everything is correct

Now, get this.   I used an audio probe and signal going in and out of Q1 was about the same volume.  Signal into Q2 was louder than out.  So I adjusted the bias until signal was louder and overdriven.  Went to Q3 where there was no signal and adjusted the bias until there was sound.  Same for Q4.  Voila!  Pedal makes sound come out of the amp.  Tone stack works properly.  Went and checked the drain voltages of the now adjusted Q2, Q3, and Q4 and all of them read 0v.  So...now what?  apparently, 4.5V is too much adjustment as it chokes the signal from reaching the output of the pedal.  So...where do I aim for proper adjustment?  I know everyone says by ear but I don't know what I am listening for.  It doesn't help that there are only a few videos of this pedal online with sound clips.

[idy]

Congratulations.
Adjust by ear: you put in a guitar signal (or guitar level signal like a looper).
The best method is to use your probe to listen to each Q1 with a probe: Drain of Q1, then D of Q2, then etc.
As you turn the trimmer, you will hear nothing, then a weak signal, then the signal starts to sound good, then it sounds worse, then nothing. You use your ear and pick a point in the middle that sounds right to you.
Repeat. Sometimes a little on the weak side is OK if the circuit is clipping too much later on. So you may go back and tweak.
Trimmers on the Drain is not an ideal set up, and commercial pedal builders use matched FETs that work with fixed Rs. There is no guarantee that your four FETs will ever sound "just like" somebody else's. It's a neat trick that allows hobbyists to get usually pleasant and useful sounds from a mixed bag of FETs.

[freshmex18]

Now I am wondering what the issue is since I build a Keeley Katana that had the same issue: output way below unity with the bias set at half of the supply voltage but dropping it way down to ~10% of supply voltage made it sound great.  Does that mean I have bad luck getting transistors within spec since those are 2N5484 and not J201s?  Or is that just the nature of different production runs and time that specs vary enough and you just have to adjust your builds accordingly?  Is there a general rule of thumb that you should adjust every transistor to above unity and then tweak from there instead of to half of the supply voltage?

[freshmex18]

After adjusting by ear, current biases are Q1 0.42V, Q2 0.08V, Q3 0.07V, and Q4 0.06V.  Doesn't that seem unusually low as the schematic says to bias at ~4.5? I can't crank up the amp and hear it at proper volume as it's so late but at below-bedroom levels it sounds good.

[anotherjim]

Having a drain resistor variable is a simple answer to the wide gate control voltage spec of the JFET. To fully turn off a j201 (with 0v gate) the source volts can be anywhere from 0.3v to 1.5v. You don't want them biased fully off so the numbers suggest a working bias must produce a source voltage >0.3v and that 1v would be a rough average to hope for.
Probably to suit any random j201 that meets its specs the source resistor should also be a trimmer.
To my mind, the drain trimmer might be better at a lower value with a fixed resistor in series. Now when there are designs with fixed drain resistors it's commonly chosen for about 18k, so I'm not sure why 100k is picked for the trimmers. I'd have tried 10k fixed and a 10k or 20k trimmer. The object is to make fine adjustments easier to carry out.