Re: Brunetti Mercury

Posted by Frank_NH on Feb 17, 2016; 5:45am
URL: http://guitar-fx-layouts.238.s1.nabble.com/Brunetti-Mercury-tp25277p28159.html

Check for a solder bridge.  When I had a low voltage like this, that was the problem.  From your pictures there may be a few potential spots where you may have a solder bridge between adjacent tracks.  Check it with your DVM using the continuity tester.

I fired up my Mercury tonight and it's still works.  After playing with it some, I think I may recommend the original gain pot (A250K).  It gets fuzzy but in a good way.

I also checked my voltages with a fresh 9V battery and I only drop about 1.3V across the 220 ohm resistor (implying a current draw of 6 mA).  I get ~18.3 V from the charge pump as my battery reads 9.5V.  Q1 and Q2 have their drains biased at 9.4V.  For Q1, the source voltage is 1.0V and for Q2, it's 0.26V.  Q3 is a source follower (buffer) with drain at ~18V.