Replies to This Discussion

Permalink Reply by John W on January 5, 2011 at 12:28pm

There's a short somewhere.  What do you mean "doesn't work" -- no sound at all?  Weak sound?  Crappy sound?  If you mean no sound at all, then it's almost certainly an electrical short somewhere.  I'd first check the wires around the jack, make sure that if you are using stranded wire there aren't any teeny strands floating free bridging your signal to ground. 

 

When it did work, did it work awesome until you disconnected it?  Or was the signal spotty while it was working?

Permalink Reply by MichaelS Country Boy Guitars on January 5, 2011 at 1:04pm

John, I will double check for a short. It works well with electric guitar but no sound with the piezo equiped guitars, this does not seem like a short problem as it still works when I switch back to the electric guitar, very strange, unless some short will effect the piezo pickup and not the signal from a magnetic pickup? It did work for a while with the piezo guitar but now not at all.

Permalink Reply by John W on January 6, 2011 at 2:50am

No sound at all, with the volume turned all the way up?  Very strange.

 

A mag pickup has more oomph behind it (not more voltage, more current capacity) than a piezo.  One guess is that your input impedance is suddenly way lower than it ought to be.  That might cause a piezo to drop out *some* but I'm not sure about drop out completely.  There's no volume loss with the mag pickup?  Side by side comparison with both amps, same guitar, same gain settings on the amps, and they are the same volume? 

 

Is your input stage a jfet?  You could try replacing it (and everything in front of the jfet in the signal path.)  I've never heard of a jfet failing like that but it's possible. 

 

You said you tested your piezo guitars on other amps, which reminds me of a story.  Once upon a time I had a guitar cable go bad.  Then another.  Then ANOTHER.  I repaired one, and it still shorted out again in a week or so. 

 

Of course, the fault was the jack on the guitar.  Boy did I feel stupid.  I threw out the "broken" cables too!

Permalink Reply by MichaelS Country Boy Guitars on January 6, 2011 at 3:27am

John, found the problem!  A short or faulty connection from the input to a resistor to ground, the ground was not soldered properly. Apparently the mag had enough to get by but the piezo did not. I re soldered it and all is fine.  Thanks for making me take the time to check for shorts.