suggestions or help with my BSIAB2 please

Started by dustinsitzes, December 31, 2010, 01:28:35 AM

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dustinsitzes

  I've read all of the FAQ and trouble shooting forums I could find on this website and through google searching and still I am clueless as why my pedal worked great last night and today it does not work at all. Last night i finished assembling the bsiab2 pedal and I got it to sound great! The problem I'm having now is it only worked after testing and playing it for thirty minutes last night. I tested it one more time this morning before putting it in the enclosure and I could get no sound out of the pedal unless the effect is off (bypassed). The pedal did this right when I finished assembling it the night before and plugged it in for the first time, powered by a 9-volt battery that was good, (putting out 9.2 volts.) I then plugged up the power supply to the dc bus and the pedal worked great then. I should also mention that later in the night it worked fine on just the 9-volt battery also.
     Today I plugged everything in as I did the night before and could only get sound with pedal switch in bypass mode. With the effect switched on there is no sound at all. I then took voltages from the transistors:
Q1   G.   0                   Q2   D.   9.51
        S.   0.5                        S.  5.37
        D  5.37                        G. 4.52

Q3 G.   0                      Q4   D. 9.52
      S. 4.40                           S.    4.9
     D.  5.31                          G. 4.12
Q5 G.  0
     S. 0.9
    D. 3.98

Halfway through measuring transistors I noticed the LED turned off and I lost all voltage to transistors. I traced it back and found that no voltage was going across the diode. I temporarily bypassed the diode with a jumper and was able to  continue measuring transistor voltages. The LED also came back on.
      I followed the circuit and tried to find a break in it somewhere with my multimeter but could not find one or even a loose wire or bad solder joint. I'm very experienced with soldering boards (I've done it for my job daily) so my work is pretty clean and doubt there is a solder bridge since your PCB for the BSIAB2 is very easy to work with.  Plus if that was the case the pedal shouldn't have worked before.  After about thirty minutes of looking for a break in the circuit, the LED light turned off again and there is no voltage going to transistors anymore. 
     I'm so confused how this pedal could work and sound beautifully and the very next time I plug into it there is no sound when effect is switched on. Please point me in the right direction or help me anyway you can,

Thank you,

Dustin