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Sparkplug Feedback/computer noises

Started by lespauldoc, December 08, 2014, 04:16:01 AM

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lespauldoc

Ok, just curious if there are any ideas.... I've built several Sparkplug v1s, and loved them. This rev1 is my first time building the update. So it works great OUTSIDE the box (rock it before ya box it!) with the exception of picking up a radio station. I box it and it immediately starts feedbacking this "WEEEEEEEEEEEEE" noise that gets worse as you turn up vol and gain. You can hear the guitar signal through the noise, but the "WEEEE" is pretty overwhelming.

I've unboxed and reboxed 3x now, also double check ground, solder points etc.... This is far from my first build, and I'm perplexed. Any ideas?

****I hope I didn't double post this****

madbean

When you unboxed it the first time did it still do the feedback?

What IC are you using and can you give us some voltages?

lespauldoc

i unpacked it again, and yes, it has a 'slight' feedback that is worse when I touch the transistors. Weird.
IC is the recommended 2262. At this point I think I'm going to undo all the wiring and redo it/reground. Unless you have something else.
(thanks Brian!)

blearyeyes

http://www.madbeanpedals.com/forum/index.php?topic=902.0

If you don't figure it out, read the stuff in this thread to help da peeps help you out.

lespauldoc

Well, i removed the IR transistors and put in 2n7000s (matching pins correctly). Some noise (as expected) unboxed but pretty decent. So, I'll see if that helped. Even screwing in there before the transistors gave tons of noise. This is my first time using the large military grade transistors, so maybe I damaged them clipping the top? I dunno. I'll box this and I'm building another Sparkplug for my bro-in-law for Christmas. I'll compare the 2 if they work out: 1 with 2n700 and the other with the IRs.

Any idea-- the IRF transistors must've been the culprit. Pedal works perfectly, now boxed (and sounds awesome) with 2n7000. Weird? I know I double checked the pinouts to make sure. I can only guess I may have damaged them when i clipped them.
Thanks for the help!