SRV Special has weird signal

[maurice]

I built an SRV Special (tube screamer clone) two years ago using this layout (http://www.newtone-online.nl/forum/index.php?action=dlattach;topic=2562.0;attach=2272;image)

It used to work but I haven't used it for a while, now it has a weird, broken digital distortion - From what I remember the problem used to occur at low volumes with the pedal activated, not it's constant.  Here's a sound file of the clean, then activated pedal (https://soundcloud.com/user485777105/srv-special-clean-then-effect-problem).

Anyone have any ideas what could be causing this?  Can attach images of the board and pedal if required.

Thanks folks!

[intripped]

Check voltages, expecially Vref
Use a probe to isolate the problem
If the trannies are socketed check if they are well inserted

[tranceracer]

Also, try rotating the pots 20-30 times to clean. My friend had an old fender solid state amp that made a similar noise and I had to rotate some of his pots almost 100 times before the scratching stopped.

[maurice]

I was getting no-where with this so I rebuilt it from scratch.  BUT the new board has exactly the same problem

I poked around with an audio probe but things just got confusing as the clean signal reaches a few sections but I get lost pretty quick with whatever is supposed to happen.

Here's the voltages:
9v in      9.08v

Q1
C      9.09v
B      2.33v
E      1.3v

Q2
E      2.94v
B      3.51v
C      9.08

IC1
1      1.84v
2      1.84v
3      1.84v
4      0v
5      2.01v
6      2.01v
7      2.01v
8      9.08v