Noise gate diy - no sound

[Rethfing]

Hey, another topic - another problem. Just built Noise Gate from this schematic and pcb layout (http://www.efekty-diy.pl/pdf/Noise%20Gate.pdf) and I get no sound at all, nothing.
Here are the voltages that seems fine:
Q1:
9
4.15
3.71

Q2:
4.42
4.88
4.88

Q3:
4.42
0.48
0

Zener:
0
4.88

IC:
1. 8.38
2. 3.19
3. 4.65
4. 0
5. 4.21
6. 4.42
7. 4.42
8. 8.98

Note that C5 on PCB is shown as polarized capacitor, though in the parts I've got from the guy that sells that PCB this capacitor is just normal ceramic - but I dont think thats the case. I have no idea whats goin on. If someone could check if the PCB layout and schematic is OK I would be grateful.

[Rethfing]

I just did audio probe and tested the circuit. The sound Im playing is not getting through resistor and transistor (there is sound on 2 pins, but on 3rd I dont hear anything). I checked all resistors before soldering for proper values, it must have broken during soldering (which is weird cause Im pretty good at it). Gonna replace this resistor and tranny tomorrow and see what happens.

[Pyr0]

The voltages on pins 1 & 2 of the IC are not right. They should be close to what pin 3 is.
Double check R8 and also check for solder bridges in that area.

[PRR]

C5 is leaking.

[Rethfing]

2.2uF is weird value, I can replace it with some 10uF polarized with no problem right?
Edit: Im going to use 1uf, closer to 2.2 than 10

Oh and btw... How do you people know whats wrong?

[Rethfing]

OK the signal is going through, but the sound is very distorted and buzzy. Audio probing!

Still same, signal is not getting through one resistor, even when replaced. Dont know why is that. Resistor is 470k near the input.

IC voltage seems normal now:
1. 4.90
2. 4.88
3. 4.65
4. 0
5. 4.22
6. 4.42
7. 4.42
8. 8.98

I checked it with other IC and its the same, Im guessing that its some transistor fault, but Ill wait for some replies first

[PRR]

> How do you people know whats wrong?

Say I come to you for guitar lessons. I can't play this certain chord, it sounds awful. You, with guitar experience, look and see my one finger isn't really on the fret, and it's the wrong fret, another finger slops-over and buzzes an adjacent string... Or say you are a plumber. I say there's yuck coming up the shower drain. Your experience takes you to the main pipe in the celler, a best-first-guess where the real problem is.

Combination of study and hard knocks.

> signal is not getting through one resistor

Signal does not go -through- R3. It pulls Q1 base toward 5V DC to make Q1 work.

The debugging page didn't mention transistor voltages? Q1 base and emitter, Q2 base and collector. (Do all three pins on each transistor-- it seems "obvious" that Q1 C is at +9, Q2 E at zero, but in debugging we have to check the "obvious".)

[Rethfing]

I've replaced all transistors and nothing changed, so I guess they are OK, but Im going to measure their voltages again and post them today or tomorrow Just came back from Must Be The Music pre-casting and Im exhausted!

And one more question: Is it even going to work properly? Because the pcb layout and schematic is very different from tonepads.

[Rethfing]

Q1 (2n3904):
C: 7,31
B: 3,44
E: 3,06

Q2 (2n5952):
D: 3,97
S: 3,97
G: 3,60

Q3 (2n3904):
C: 3,60
B: -1,50
E: 0

Thats what I measured, I see something is wrong. My power supply is OK.

You know what guys... @#$% it :d Im going to order some parts and build this on tonepad PCB. At least I will be sure that PCB is fine.

[PRR]

> Q3 B: -1,50

There's no negative supply. So how can this voltage be negative? Most likely theory: U1A is oscillating. If it happens when RV1 is se mid way, then it is Q3 or U1A output getting into RV1 wiper. Layout problem. The PCB does not have an obvious too-close problem, but RV1 wiper is an external wire which must not run over/near the Q3 end of the board.

[Rethfing]

I just built noise gate from tonepad, but I didnt saw that there are 2 versions, and I built the first one. Anyway it works, but I think it needs some tweaking. I replaced 680ohm resistor with 4.7k as suggested and it works a lot better. Just one problem - I hear some weird clicking sound while playing with noise gate engaged, its like the signal is touching ground or smth like that. Any suggestions?

[Rethfing]

Nevermind, click is gone, dunno how, but its OK now