Griton debugging

[tagotis]

Hi everyone, I am currently trying to build my first diy stompbox and I am having some trouble to get it to work properly. The effect is a Griton from Tonepad:

http://www.tonepad.com/getFile.asp?id=81

I think every component is of the value needed. I used 2 tantalum caps as told and electrolytic caps for 10uF and 47uF values. I chose symmetrical clipping so the third diode is replaced for a jumper.

When tested, bypass mode works nicely but when the effect is engaged there is almost no sound coming out (but there is). I am using an Electro-Harmonix adaptor which yields about 9.85V according to my multimeter (advertised as 9.6).

I have built an audio probe and the sound seems to lower when it gets past de IC. I replaced the IC but it works the same.

Here are some readings:

IC
P1  4.91
P2  4.94
P3  4.90
P4  0
P5  4.91
P6  4.91
P7  4.91
P8  9.85

Q1
C  9.85
B  3.72
E  3.21

Q2
C  9.85
B  3.73
E  3.22

D1
A  4.94
K  4.91

D2
A  4.91
K  4.94

D3 - jumper

And here some shoots of the PCB:

http://www.aronnelson.com/gallery/main.php/v/diyuser/2012-12-10+12_23_45.JPG.html

http://www.aronnelson.com/gallery/main.php/v/diyuser/2012-12-10+12_24_18.JPG.html


Any kind of help is kindly appreciated, if you need any more info just ask!

Thx in advance

[Seljer]

after which half of the IC does the sound disappear? at pin 1 or at pin 7?

[tagotis]

Hi Seljer, I have tested each pin of the IC using the audio probe, here are the results:


P1  No sound
P2  Almost no sound
P3  Sound seems correct
P4  No sound 
P5  Almost no sound
P6  Almost no sound
P7  No sound
P8  No sound

Hope it helps

[tagotis]

Well, I rechecked everything, all solder joints seem good and all components seem the correct value (just replaced a resistor which was higher than it should, but no change in behaviour). I dont know what else I can do...

Can anyone please give me any advice?

Thx

[Seljer]

I'd wager a chance that your opamp may be dead for some reason (which is strange because its socketed and all the voltages seem to be ok). Try putting whatever other dual opamp you may have on hand to verify it still doesn't work.

edit: or shorting together pins 1 and 2, forcing the clipping section be become a unity buffer that pass at least some audio