Strange Distortion Pot issues (Any ideas anyone???)

[comfortably_numb]

So I finished wiring up my take on the Dist+ last night.  After actually inserting the IC (duh) I got an extremely faint signal.  So I played around a bit with the wires, checking for loose joints, but found nothing.

Then it happened...when I touched lugs 1 and 2 on the volume pot I got sound.  Still not satisfactory, but much much better.  Then, when I tilted the pot a certain direction, the signal came to full strength and sounded great.  I did some experimenting with this.  Just tilting the pot, just touching one of the lugs, then the other.  Repositioning the wires instead of moving the pot. 

It seems though, that I only get a decent signal when I touch both lugs 1 and 2, and tilt the pot in that certain direction (which happens to be toward the circuit).

Strange no?  Do I have a screwed up pot?  Cold joints (I don't think this is it)?  Anyone?

Thanks,
CJD

[petemoore]

  Everything seems wierd and unexplainable until you figure it out.
  I'd maybe measure the pot, but I doubt it's the source of trubble, I've had very few pot problems.
  From the descript it seems there may be a faulty connection.

[comfortably_numb]

Well I fixed it.  I now have a kick ass distortion pedal.  (I'll post seperately when I get it housed with pics and clips and all!) 

Wanna know how I fixed it?

I rewired everything...  No dice.

I rewired the tone pot that it connected to...  No dice.

Then I figured, if it only works when I'm touching both lugs 1 and 2, why not just wire them up?  BINGO!

Any takers on why this happened to fix it perfectly?  I have a nice volume taper too.  Nothing weird.  Go figure.

Thanks,
CJD

[comfortably_numb]

Okay, I take it back...  It worked once.  Actually, that it worked kinda perplexes me.  It worked, with volume adjustment, when the wiper was connected to the outer lug which was connected to the output jack.  In effect, the signal was connected straight through to the jack.  But once, I repeat ONCE, it worked, with volume control.  Strange.

But then it didn't work.  And now it's doing what it should...  sending signal, without volume change, to the output jack. 

I'm afraid I have a bad pot, but I'm gonna wire it up in reverse to see what happens.

[Morocotopo]

Bad pot. Throw it in the garbage. Happened to me many times, I think defective construction. Don´t waste your time, it might work, or stop working at the worst moment...

[comfortably_numb]

I think you're right, as the sound quality is deteriorating everytime I test it.  It crackles and sputters.  Very strange.  Must be a bad pot.  Any other ideas anyone?

[Gilles C]

A bad pot.

It happened to me too. The lugs are not soldered inside the pots. It's rivets that hold the lugs to the pot itself. Sometimes, they get loose, or were loose when you bought the pot.

It happens to me when I move the lugs from side to side sometimes. Bad, bad.

Check this http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

You'll see what I mean.

When you put your fingers between the lugs, you're adding some resistance in parallel with an open circuit (the bad pot), that's why it works a bit when you do that.

Gilles

[Mark Hammer]

That's why I use this stuff: http://www.stabilant.com/

Amazing, amazing stuff, and if you don't live in the world of "I have a bin full of 500k pots, so I'll just pull out another" a real life saver.  I cannot begin to count the number of I-thought-it-was-a-writeoff projects this has helped me revive over the past 6 months.

[Roobin]

Yeh, one of my pots went funny. Jsut after I debugged the circuit as well! If i pushed down, it would work, and liek one of those taps, it popped up slowly and nothing. So I replaced it and its better.

[Gilles C]

That's why I use this stuff: http://www.stabilant.com/

Amazing, amazing stuff, and if you don't live in the world of "I have a bin full of 500k pots, so I'll just pull out another" a real life saver.  I cannot begin to count the number of I-thought-it-was-a-writeoff projects this has helped me revive over the past 6 months.

Indeed Mark, that stuff does wonder. We use it at work, and they have to keep it in a locked drawer to be sure it will not evaporate too fast  they also say it is costly.

I'll have to buy some for myself soon because they are shutting the door of the technical department where I work in July.

Gilles

[R.G.]

There is a story about Bob Widlar, the circuits genius that was personally responsible for lots of National Semiconductor's huge advances in opamps way back when.

The story is that when he was in the lab and found that some experiment of his was messed up by a faulty component, he would calmly take the component out and go over to the mechanical-construction bench. There he would lay the component on the flat anvil part of the bench vise and use a ball peen hammer to pound the component into dust. That way he could be certain that the faulty part would NEVER find its way back into the parts bins to foul up another experiment of his or anyone else's.

Widlar is also the guy who, during a big economy drive at National Semi sent in purchase orders for 200 feet of rope and two goats. Bob was held in such high esteem that a few days later a truck showed up with his rope and his goats. This is in the highly urban center of Semiconductor Valley, mind you.

Bob signed the receipt, led the goats out into the front lawn which had gotten a bit overgrown and weedy when the suits in the business office had cut back on the lawn mowing budget, and staked the goats out on the front lawn. He then went back into his office, locked up, and left on two weeks' vacation. The lawns were neatly mowed when he got back. Nobody knows what happened to the goats.

But I digress.