Spin Semiconductor

Hi, it's me again with another FV-1 issue!

I've built another FV-1 based guitar stompbox, and loaded GA demo programs into the EEPROM.
For most of the time when I power on the unit, the overload LED lights up constantly and there is no sound.
Other times it works fine for a little time(a mininite or so) and the sound quality is nice; but then makes some crazy popping sound and the LED keeps blinking and suddenly after there is no sound!
What could cause this problem? Here is the schematic and the PCB layout I've been using:
https://db.tt/015nK6aO
Please help me through this...
Thanks

Are D14 & D15 orientated correctly on the PCB?
Try a capacitor (e.g. 1uF) between the node R9/D14/D15/C13 and the pins1/2 of the FV-1.
Or you could first try to lift/disconnect one leg of each of those two diodes,
and check if the circuit still misbehaves...

Thanks for the reply.
Those diodes are there to protect the ADC input from high level signals, I suspect that those areresponsible for the misbehaves because this afternoon I played for about half hour without any problem!
I will disconnect those clamper if the problem happens again.

It`s clear why you put those diodes before the input of U1.
Try that cap before pins1/2.
We do not know how the DC voltage of those pins behave during power-up;
One of the diodes might get "DC-conductive" from the chip`s wandering input-pin DC-voltage...
That`s different from the case how the diodes are intended to work,
namely shunting an "AC-overvoltage" of the signal to the power-rails ( = "AC-ground").

Ohhh, now I get your point. I'm gonna include the cap and see what happens...
Thanks again

Surprisingly the circuit stopped acting crazy by itself! So I didn't even include the 1uf cap.
I noticed that at the startup the overload LED turns on for about a second and then the circuit works nice without any issue, is that normal or it's because of the diodes? Can those diodes harm the FV-1 in any way?
Sorry for asking too much stupid questions...

See also Sandrine`s reply here:
http://www.spinsemi.com/forum/viewtopic.php?t=541