My DIY stombox is just sending static until I touch audio cables exterior metal

Started by JoshMandic, September 26, 2014, 07:20:24 PM

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JoshMandic

I feel like it might be a grounding issue. The only changes I made it from the schematic of the muffmaster found at http://www.muzique.com/schem/projects.htm was; changing the 1uf polarized capacitor to a non-polarized, using a 3094 transistor instead of the 5088, and substituting a DPDT stompswitch for DPDT toggle on/off, and 100k stereo potentiometer. I don't think that any of that would cause this effect where I need to touch the audio cable (from guitar to circuit) at the end going into the circuit to hear the guitar.

My only thoughts for why this could be, is maybe I didn't need a ground style input jack. Or I need a better ground.

I appreciate any insight you could shed on my case! Thank you, sincerely Josh

Quackzed

I think you're on the right track, sounds like a ground issue, double check that ALL your ground points are connected to ground, jacks battery etc? double check r1 is 100k and its grounded/not a cold solder joint...r1 could be the culprit, if unconnected to either side the transistor wont be referenced to ground/ biased ... even just re-flow the solder points wherever they look funky... even where they don't , there aren't that many really...   
nothing says forever like a solid block of liquid nails!!!

Quackzed

 :D it could also be a bad guitar cable...  :-X you touch the outside of the jack and the pressure 'connects' the intermittent "bad" cable end... i'm gonna guess cable  :D
nothing says forever like a solid block of liquid nails!!!

JoshMandic

Quote from: Quackzed on September 26, 2014, 07:37:55 PM
I think you're on the right track, sounds like a ground issue, double check that ALL your ground points are connected to ground, jacks battery etc? double check r1 is 100k and its grounded/not a cold solder joint...r1 could be the culprit, if unconnected to either side the transistor wont be referenced to ground/ biased ... even just re-flow the solder points wherever they look funky... even where they don't , there aren't that many really...   

Thank you for your help, I actually was looking over the circuit and found I'd wired the output jack reversed and had the wrong style input (grounded style) jack which was connecting the tip to ground.

petemoore

 It could be a simple boosting of the existing input hash.
Try a different cable. Test all points marked ground. if it is boosting, the circuit is probably otherwise wired correctly.
Convention creates following, following creates convention.