Re: Brunetti Mercury

Posted by Frank_NH on Feb 16, 2016; 2:55am
URL: http://guitar-fx-layouts.238.s1.nabble.com/Brunetti-Mercury-tp25277p28104.html

Hi Paul,

Thanks for hires photos.  If you have an audio probe, check the following points:

* pins 3 and 6 of the IC.  That's where the signal enters and exits the op amp.
* the gate of Q1 (very bottom leg)
* the drain of Q1 (top leg)

That's enough to check to see where the signal is getting lost in the IC.

Also, you should be getting ~18V (less diode voltage drop) from the charge pump, so pin 7 of the IC should be close to that.  The bias voltage should be half that (~9V) and you should see something like that voltage at pins 2, 3, ans 6 of the IC.  Also, pin 4 should be ground.  Pins 1, 5 and 8 are not connected.

Let me know what you find.  We'll go through this step by step and figure out where the problem is.

And, as always, check for solder bridges and cold solder joints.  A solder bridge got me in a recent OD808 build...