Ready to break something...

[Greek Acrobat]

I'm sure this is something so simple but I just can't figure it out. Any insight would be great...

Every circuit I build works fine for 2 minutes (if that) and then goes very quiet and the guitar sound turns crackly.

Am I putting an electrolytic in the wrong way round? I don't think I am but it's my best guess at the moment. Overheating the IC on soldering was my first thought but I get the same problem with circuits I breadboard.

lol, here's a thought... could I be mixed up about the poles of the battery?? Lordy, that would be embarassing!  :oops:

If I had patience I would be sitting trying to methodically work out the problem but I stormed out of the garage in a fit of frustration. I don't think my soldering iron will take me back without a big apology.

[AL]

Well, before you get too frustated how about some more info?  What are you building?  Is it in an enclosure?  What type?  New components?  Correct components?  Every circuit works that way?  How many is every? Battery or power supply? There's a good bit of variables here and without knowing exactly what you're building there are too many possibilities. Post some more info and take it from there.

AL

[Greek Acrobat]

Yeah, sorry. More info...

When I say 'every' I mean the last few I've tried. They've all been IC based circuits.  The one I'm trying right now is a simple buffer using a TL071. About as simple as I could get it, 5 resistors, 4 caps, 2 of which are electrolytic. Using a battery with a snap.

All components are new. Two of the resistors are 2.2M instead of 2M but the rest are correct values. It's not in an enclosure but I'm pretty sure that's not what's causing the problem.

I think I scribbled down the schematic from a web page a while ago. I'll try to find it but I think it was an obscure page somewhere.

[Chris R]

did you test your battery voltage ?

if you used the same battery in your latest circuits.. that could be the problem.

I actually rebuilt a fuzz a couple times one night because my battery was dead.. doh.

C

[AL]

Check the obvious first before you go tearing anything apart (like I do .... doh!!).  Battery (as Chris R suggeted), electrolytics, make sure polarity is correct on everything, check grounds.  I would recommend building RG Keens Audio probe if you haven't already.  It's a very quick build and I have used it countless times to debug circuits - after you build one you'll wonder how you made it through life without it.

AL

[PB Wilson]

More than once I've forgotten to put ICs and transistors in their sockets. I spent a good deal of time with my first build checking solder joints, wiring, everything I could think of until, DUH, I figured it out. Hopefully it's something easy. I'm thinking of picking up a PT-80 that never worked and taking an audio probe to it. I know how you feel and it don't feel good! Hang in there.

[Hal]

yea, i agree...check battery voltage.  Thats kinda what it sounds like...working for a second or 2 and then dying.  Batteries do that...release a spike of charge and lower out when they're not quite dead...

[TheBigMan]

It's rarely anything as complicated as you think.  Take myself, I'm a pretty good solderer, but I had a distortion pedal that didn't work when I fired it up.  Checked all manner of things, replaced electrolytics, tested opamps etc.  I nearly took every part off that damn board, until I decided to check my soldering.  Five seconds under a magnifying glass and I spotted a bad joint at the input buffer FET.

Like the other guys said, check everything that's simple first.  We've all cross wired jacks or put opamps in the wrong way or missed a bad solder joint.  It comes with the territory.

[The Tone God]

By ICs I assume we are talking about opamps. If its not the battery then you could have other issues. If you touch a input/output cap and the signal comes back then dies again you might have a leaky cap. You could try connecting a resistor to ground on the cap to get things working again but thats kind of a bodge. The other issue could be bad biasing. Check your voltage readings.

I hope this helps.

Andrew

[Greek Acrobat]

Thanks folks.

Andrew, a couple of the circuits are op amps but one was using a 4049 with the same problem. Leaky caps are a possibility - I'll be sure to check that out.

Battery voltage is another one to check. I thought the battery was good but didn't think to check. I guess this is pretty much all simple stuff. I'll sit down tonight and give it a proper look over.

I think I need to learn a little patience.  :roll:

[Sic]

Hung By A Thread?

[Greek Acrobat]

Hung By A Thread?

yes