need some help with my naughty fish

[hobbits]

Dear forum members, Last weekend i build a naughty fish pedal. But i have a problem with the down (when the led should be on and with signal the led is fading) setting. I compared my measurements with other posts but i still can' t pin point it to my problem i hope there is somebody here who can give me directions.

Thie are my measurements:

Vin   9,01
   
IC1   
1   0,02
2   0,02
3   0
4   -6,74
5   0
6   0
7   0
8   7,32
   
IC2   
1   1,75
2   0,01
3   0
4   -6,72
5   2,7
6   2,9
7   4
8   7,3
   
IC3   
1   0,03
2   0,02
3   0
4   -6,73
5   0
6   0,02
7   0,12
8   7,3
   
IC4   
1   0,81
2   3,5
3   0
4   -3,5
5   -6,71
6   2,54
7   1,39
8   7,29
   
Vactrol 1   
C   2,4
A   3,98
   
Vactrol 2   
C   2,4
A   3,99

however when i use a voltage in 12,4V the pedal seems to be working fine. Is the 9 volt to low to feed this pedal?

thanks in advance

[midwayfair]

Something's pulling your supply voltage down to only 7.32V. What are you powering the pedal with for 9V?

The "down" mode is also very picky about settings and how hot the input signal is (gain setting), so what settings are you trying this in?

[hobbits]

My measurements where done in the down mode and the power comes from a normal 9 volt adapter giving me exact 9,01 volt and enough ampere. With the gain full open and my guitar plugged direkt in the pedal. I already checked the solderings ans the resisters from the pcb.

It' s just like you wrote "somethings pulling down the power"

thanks for thinking along with me.

[hobbits]

Which resistor is responsible for the drop of volts ?. it is the R25 (47R) . Can I choose a lower value for this?

[TGP39]

Are you sure D4 is a 12 volt zener diode?

Steve.

[midwayfair]

Which resistor is responsible for the drop of volts ?. it is the R25 (47R) . Can I choose a lower value for this?

Yes. You could jumper it and remove D4 if you are going to be using a regulated power supply. Sometimes the charge pump can try to draw too much current and that little bit of resistance becomes a problem. (Did you use the LT1054 for the charge pump?)

[madbean]

Which resistor is responsible for the drop of volts ?. it is the R25 (47R) . Can I choose a lower value for this?

Yes. You could jumper it and remove D4 if you are going to be using a regulated power supply. Sometimes the charge pump can try to draw too much current and that little bit of resistance becomes a problem. (Did you use the LT1054 for the charge pump?)

Seconded. Jumper the resistor and see what the measurement is after that.

[hobbits]

Great answers. I will try things tomorrow and let you all know (rehearsel tonight). And to Steve yes it' is a 12V zener.

[hobbits]

Dear all, With the removal of r25 (jumper) the "main" voltages changed from 7,32 to 8,25. The led in the down position is now on and the pedal is working naughty fine. So you all made my day. I wish you also a great day.