Box of rock clone, volume problem

[x-pro]

Can you see a photo of the PCB from the soldering side?

[ricci]

Maybe the author has pin 3 of the LEVEL regulator connected to +9V instead of GND?
But then it is not clear why these voltages drop when C6 is turned off ?
Something is wrong with the mounting or tracing of the PCB.

Unfortunately in most of the diagrams of this pedal that are online, the potentiometers are indicated with lug 1 and 3 inverted, therefore in the volume pot it is lug 1 that must go to ground and not lug 3 as in the diagram, the the bad thing that could have happened is that it would have worked in reverse, exchanging clockwise with anticlockwise.

I reiterate that the wiring is correct, there are no GND or VDC going where they shouldn't go.

[ricci]

is the board cleaned of flux? they can be conductive

This is one of the concerns I've always had when using solder paste or flux. However, yes I have always tried to clean well.

[Helmholtz]

The DCV after C6 must be zero. Also there should be no ouput with C6 disconnected.
You have a problem after the drain of the third Mosfet.
The circuit works fine up to that drain as seen in the scope pics.
But we didn't compare output signals.
I suspect some unwanted leakage between the ends of C6.
Use your meter to check/compare circuit resistances.

Maybe post pics of your board.

[ricci]

C6 should block the DC but I replaced the C6 cap with a 47nf ceramic one, now VDC after C6 is 0.09V but the problem is still there.

Here in Italy it's 2 am. Good evening to you and goodnight to me, I will read to you tomorrow.

[x-pro]

The resistor near the yellow wires is rated at 12k. Where is it in the diagram?
Is the resistor coming from the switch not too large? It could be color-coded: 130 ohms, 330 ohms, 430 ohms.
Can you see a photo of the PCB from the soldering side?

[Helmholtz]

C6 should block the DC but I replaced the C6 cap with a 47nf ceramic one, now VDC after C6 is 0.09V but the problem is still there.

Ok, 0.09VDC is close enough to zero.
Shows that there was some problem before.

Now, 47n is about a factor of 20 lower than 1µ.
Means that output should be weak and trebly.
Replace C6 with correct 1µ value and observe polarity (positive end to drain)

[ricci]

Ok, 0.09VDC is close enough to zero.
Shows that there was some problem before.

Now, 47n is about a factor of 20 lower than 1µ.
Means that output should be weak and trebly.
Replace C6 with correct 1µ value and observe polarity (positive end to drain)

I did the same on stripboard (veroboard), later I want to check this route too.

With 1uF polarized correctly the output is always weak and the tone pot from 0 to 5 not only does not brighten the sound and has no gradual excursion but the output feels as if there was a blanket in front of a speaker, so it influences also the volume. Someone solved this with a 56nF which I don't have and I tried a 47nF. At least it has a gradual excursion and without the "blanket" problem.

[ricci]

The resistor near the yellow wires is rated at 12k. Where is it in the diagram?
Is the resistor coming from the switch not too large? It could be color-coded: 130 ohms, 330 ohms, 430 ohms.
Can you see a photo of the PCB from the soldering side?

If I understand correctly what you are saying, that is an 82k and the resistor for the LED is a 330ohm

[ricci]

Can you see a photo of the PCB from the soldering side?

eccolo

[Helmholtz]

With 1uF polarized correctly the output is always weak and the tone pot from 0 to 5 not only does not brighten the sound and has no gradual excursion but the output feels as if there was a blanket in front of a speaker, so it influences also the volume.

If so, the 1µ cap probably was bad.
A lower value cap can only reduce bass content.

[ricci]

If so, the 1µ cap probably was bad.
A lower value cap can only reduce bass content.

in fact those who replaced 1uF with 56nF did so to reduce the bass which with gain almost at maximum produced a very muddy distortion

[ricci]

If we want to be honest, the jtm45 works exactly like this... in many Hendrix songs you can hear this sound, some time ago I didn't like it either but it depends on the genre you play and the playing

[g1]

The unit that has the sound that you like, what cap is it using there, 1uF or something else?

[ricci]

If so, the 1µ cap probably was bad.

I also have to say that since I built the pcb and noticed this problem, I have replaced the 1uF cap maybe 4 times.