Sunking problems...

[gtr2]

It's an incredibly useful debugging tool.  A DMM will only get you so far.  Plus it only takes minutes to make!

Here's a link to the debugging wiki on DIY stompboxes it goes over using an audio probe.  It's really simple.

http://www.diystompboxes.com/wiki/index.php?title=Debugging

Hope this steers you in the right direction!

josh

[jkokura]

Yes.

DMM's are only really good at some very small things when it comes to debugging. They are useful, don't get me wrong, but the audio probe is much more useful.

Jacob

[pauloman80]

Okay, built me an audio probe.  Now to hit the diystompboxes link and start the debuggage...

I'm going to presume the pedal should have power running to it, yes?

[gtr2]

Okay, built me an audio probe.  Now to hit the diystompboxes link and start the debuggage...

I'm going to presume the pedal should have power running to it, yes?

yes

you need also need to ground the probe to the circuit ground as explained in the link

keep the volume very low on whatever your plugging into until you get a handle on the volume

josh

[pauloman80]

Done and done.  

Okay, the weirdness has begun at the gain pot.  Now, I don't know how exactly a pot is *supposed* to function, but it would stand to reason (in my mind at least) that both sets of lugs should behave the exact same way when the pot is turned, as a dual-gang pot is essentially two pot stacked on top of each other and controlled by a single shaft.  If that's true, it doesn't appear to be the case for this pot.  I've described the resulting audio below with the pot starting at all the way turned down and then cranked all the way up...

Top set
Lug 1: audio is always on
Lug 2: audio starts at full volume and evenly reduces to full quiet
Lug 3: no audio

Bottom set
Lug 1: audio level starts at full quiet then appears to reach its loudest level after barely 1/4 turn
Lug 2: no audio
Lug 3: audio level starts at full quiet, turns up to full volume, then all the way back down again to full quiet

Due to time I've got to wrap up working on this thing today, but this doesn't seem right to me at all.  Did I install a faulty pot?  My local building buddy informed me of the trick of using resistors to make the pot circuit wide open, but I wasn't in a place where I could write down any notes.  Anybody know this trick and willing to give me a quick rundown on how to o it?  I still think the pot is a culprit, but I'm not going to rule anything else out.  Also want to replace IC1, it may have gotten overheated while I had the wrong charge pump in there.

[gtr2]

Could you post a pic of your gain pot wiring?  It's hard to see in your previous pics.

josh

[pauloman80]

Could you post a pic of your gain pot wiring?  It's hard to see in your previous pics.

josh

Not currently in a position to post a closeup of it, but I can describe it for ya in über detail if that's okay:  

Looking at the front of the pot with the shaft up and the lugs facing you, I've got from left-to-right as 1-2-3, color coded Orange-Green-Blue.  They attach to the board from the component side, but in reverse order as on the board it's labeled 3-2-1 from left-to-right (Blue-Green-Orange): top set of lugs connects to Gain 2 and bottom set to Gain 1 (this lines up with what I saw in other users' Build Report pics).

I quadruple check all my wiring and polarity during assembly these days as not doing so bit me in the butt on my first couple builds and forced me to disassemble numerous times.  However, now looking closer at the Gain 1 and Gain 2 wiring, it's possible that my wiring is only 90% accurate, but from what I can tell, I've got it wired exactly like the other builds I've seen in the Build Reports threads.

[gtr2]

In your description above instead of top set, bottom set could you label it gain 1, gain 2 so we know what's going where.

[pauloman80]

In your description above instead of top set, bottom set could you label it gain 1, gain 2 so we know what's going where.

Done, see updated reply above.

[gtr2]

You won't get sound out of the ones listed as "no audio" because the cap in your audio probe is blocking the dc current in those two locations.

As far as what your experiencing elsewhere, I'm not sure exactly.  Or if it's even right.  I don't have a sunking build on hand to check.

Hopefully someone can guide you in the right direction.

[pauloman80]

Thanks, Josh.  Makes sense on those no-audio lugs. 

Didn't get a chance to continue testing with the audio probe today, and I won't for the next several days.  Headed to New Orleans with the wife tomorrow through Sunday.  Maybe the wonderful eggheads around here will be able to come up with a few different troubleshooting options that I can work through upon my return. 

Thanks all!  See you in a few days.

[bigmufffuzzwizz]

Have you tried testing the pots that you are not sure about with a DMM? Then you can rule that out at least.

[pauloman80]

Have you tried testing the pots that you are not sure about with a DMM? Then you can rule that out at least.

I did, but the one in question appeared to behave exactly like the other two, and the other two are working just fine.

[gtr2]

Ok, so I've got a sunking build I just built up just for you...   I mean me...  It's fully functional and sounds really great with just some 1n34's.

Here's what I checked out for you:

My IC voltages are pretty close to madbeans in the build docs.  Mine are slightly higher due to a input voltage of around 9.6v

I took out my diodes (well they were just breadboarded..) to keep it close to your build.

Then I took my probe and found the following...

Top set - Gain 2
Lug 1: audio is always on same
Lug 2: audio starts at full volume and evenly reduces to full quiet I found it a little different, here's a sound clip http://soundcloud.com/1776-effects/gain-2-lug-2
Lug 3: no audio same

Bottom set - Gain 1
Lug 1: audio level starts at full quiet then appears to reach its loudest level after barely 1/4 turn same
Lug 2: no audio same
Lug 3: audio level starts at full quiet, turns up to full volume, then all the way back down again to full quiet I found it a little different, here's a sound clip http://soundcloud.com/1776-effects/gain-1-lug-3

Both sound samples have a slight amount of clipping from my iphone mic, the pots moving from fully counter clockwise to fully counterclockwise during the boring chord that is playing.  Both of the lugs with sound clips do distort right before they go silent..(its not my phone)  You can also use the waveforms as a guide to the volume difference.

Hope this helps...

Josh

[pauloman80]

Thanks for being so thorough, Josh.  Send that Sunking my way!    Nah, I want to get my workin'.

I'm curious what the deal is with Lug 2 on Gain 2 and Lug 3 on Gain 1.  One thing's for sure, I'm definitely not getting anywhere near the right response when the gain pot is turned.  I just got back from New Orleans this evening, so later this week I should have the opportunity to continue checking the rest of the build with the audioprobe.  Just not brainy enough to know how the signal goes through the schematic and why it should respond in a particular way at particular points along the signal path.  Going to keep at it, will keep you posted.