Rosscomp distorts

[sixwasnine]

Hi,

maybe anybody can help me:
I build the Tonepad Rosscomp. Basically it works, but the output is too low and the sound is always distorted in a very ugly way.
As I strum my guitar (with single coils) stronger, the sound gets worser.
I checked voltages of transistors and IC, compared it with specs found by another more successful guy.
A 9V power supply is used.
I found another topic with similiar symptoms but with no final answer. Now I am clueless.

Thanks

[R.G.]

What to do when it doesn't work

[sixwasnine]

What to do when it doesn't work

Yes.
The question is, if there is anything obvious to check which could cause the described behaviour.

[G.Neyrey]

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Go here. This has helped us pedal builders on more than one occasion. Be clueless no more!

George

[sixwasnine]

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Go here. This has helped us pedal builders on more than one occasion. Be clueless no more!

George

Thanks. I will study it later at home.

[sixwasnine]

So I did measure the transistors again - two of them have no voltage at base:

Q1
C = 4,69
B = 4,94
E = 4,43

Q2
C = 4,69
B = 5,2
E = 4,56

Q3
C = 8,67
B = 0
E = 0

Q4
C = 8,67
B = 0
E = 0

Q5
C = 9,08
B = 8,67
E = 8,14

Bases of Q3 and Q4 are fed through an 0,01 mikrofarad capacitor. On the side of them there is voltage, on the other none.
I measured the capacity and its alright.

Two of the three diodes pass current both ways. But if I remove them from the circuit it seems alright.

Even more confused now...

[R.G.]

Just offhand, Q1 and Q2 are nearly saturated and that could be your problem.

It would be a whole lot easier if you supplied the rest of the info requested by "What to do when it doesn't work" like links to the schematic and layout and whether you made any substitutions, whether you looked up the transistor pinouts, things like that. It takes some time go go hunting that stuff down.

But look at Q1 and Q2 biasing. That's plenty suspicious.