Finally got my 10kB pots in today so I put them in and fired this puppy up and got two undesired results:
First, got the high-pitched squealing a few other guys have been talking about, so I checked the charge pump IC, and it's the CPA rather than a SCPA. That should be an easy fix once I can get to my local shop and find an SCPA (although I ended up with the CPA version the last time I went there).
Second, the gain pot does nothing. No change at all in the overdrive/clipping level when turned. Tone and volume pots function as expected. I did Madbean's Eleventy Bajillion Diodes mod (found here: http://www.madbeanpedals.com/forum/index.php?topic=1107.0), so I don't know whether I did something goofy or what. Double-checked all my wiring, including the wiring going two and from the switches for the diodes mod. Here's a couple shots of the guts:
(http://www.songbucketaudio.com/SongbucketAudio/Blank_files/IMG_0456.jpg)
(http://www.songbucketaudio.com/SongbucketAudio/Blank_files/IMG_0459.jpg)
Thanks in advance to any and all who have input and can help me get this puppy running!
Gain pot does nothing: could mean a couple of things.
Gain pot wired wrong
Vb not correct
Diodes incorrect/bad or shorting out
First step to fix:
Temporarily disconnect wires to all clipping diode switches. Tuck the wires somewhere so the leads don't touch anything (or each other)
Does the gain pot do anything now?
Gain pot is definitely wired correctly. I double & triple checked the lugs. *CORRECTION TO ORIGINAL QUESTION: There is something going on when the gain pot is turned: there's an extremely slight difference in volume.
What's the Vb? Still noob-tastic here & there. :-[
It's certainly possible the diodes aren't set up right. Does it look like there's possibility of shorting from the photo? As hewn together as it may look, I took extreme care in preventing any shorts as that was a major problem with my very first build. Warming up the soldering iron now, will disconnect the diode switches and see what's what, post again shortly...
BTW, this thing will at least look amazing. The faceplate you sent me really sets it off. I'll be that much more excited when it's working!
***UPDATE*** Same behavior as before when the diodes are removed from the signal path. The gain knob still decreases the volume slightly when turned up, and the high-pitched whine (presumably from the charge pump IC) goes away when the gain pot is as 12 o'clock high but increases when turned in either of the other directions.
Vb is the bias voltage supplied to both the ICs and the gain pot. There is a voltage divider made of of two 27k resistors in the power section. This takes the supply and cut it in half. If there is a problem, or incorrect value in one of those resistors, it will throw the bias voltage off and that can tank the whole thing.
I would take some voltages with your DMM on all the IC pins and the 6 lugs of the gain pot and post them. That will help a lot. Although you do have the incorrect charge pump, the effect should still work.
What kind of power supply are you using? If using a wall wart, try battery. The typical Boss 9v WW puts out closer to 13v nominal, which could damage the charge pump.
Gotcha... I think. ;D Still learning. I checked those two 27k resistors earlier today and they appear both to be the correct values. I'll have to check the IC and the gain pot tomorrow when I get back to the office. I sure hope it's not the gain pot, I installed the one you sent me, and I would hate that you accidentally grabbed a dud! :-[
My local building buddy thinks it's possible having the wrong charge pump would alter the amount of audio signal, but I can't remember exactly where along the signal chain he said it would be and how he described it. Something about only half the audio signal going where it needs to go. He's substantially brainier than I am at this, so I thought I'd pass his thoughts on to you and see what you think.
I'm using the typical Boss power supply, didn't wire up a battery connection. Never do, batteries irritate me. I've got a Voodoo Lab Pedal Power 2 Plus, would that be "safer" to power it with? Ideally I'll be powering from that source anyway.
Got a guide or walkthrough on checking IC pins and the gain pot lugs? Links are always good. Thanks, Brian. You're the man.
Okay, testing the IC's.
IC1 (TL072)
Pin 1: 4.78
Pin 2: 4.78
Pin 3: 1.25
Pin 4: 0.00
Pin 5: 4.72
Pin 6: 4.78
Pin 7: 4.78
Pin 8: 9.52
IC2 (TL072)
Pin 1: 4.77
Pin 2: 4.77
Pin 3: 4.72
Pin 4: 0.57
Pin 5: 4.72
Pin 6: 4.78
Pin 7: 4.79
Pin 8: 8.23
IC3 (ICL7660CPA) -should be SCPA, but like you said, it should still work.
Pin 1: 9.52
Pin 2: -0.02
Pin 3: 0.00
Pin 4: 0.46
Pin 5: 0.57
Pin 6: 2.62
Pin 7: 0.24
Pin 8: 9.52
Gain Pot (100kB dual)
**Top Row
Lug 1: 4.72
Lug 2: 4.72
Lug 3: 4.71
**Bottom Row
Lug 1: 4.71
Lug 2: 4.71
Lug 3: 4.71
Double-checked all my solder joints and points with a magnifying glass... easily the cleanest soldering job I've ever done. Also double-checked the 27k resistors in the voltage divider section, both are spot on.
Thoughts
On IC2, you should read -9v on pin4 and about 17.5 on pin8. On IC3 you should read -9v on pin5.
So, something is wrong at the charge pump. It could be a bad charge pump, or possibly one of the electrolytic caps is pointing the wrong way (C20 onward) or one of the 1N4001 is bad or pointing the wrong direction.
Can we get a pic of the topside?
Triple-checked all my caps, their polarity is good. Also checked my 4001s, polarity is good there as well. Just checked them both with the diode setting on my DMM, both are registering between 0.593 and 0.596... does that sound right?
I suppose it's a good sign that only those three values are wacky and they appear to all be tied to the charge pump. I just remembered that I have a couple more 7660s, I should try swapping it out for a new one. Let me try that first, if it's still wacky I'll update this post with a shot of the topside and we'll go from there.
**EDIT**
Swapped out the charge pump, values still aren't matching what you said they should be, and they're different from what they were before. IC2 Pin 4 now reads 5.81, Pin 8 reads 8.45. IC3 Pin 5 reads 5.38. Tried running my guitar through it to see if I could get sound. Bypass signal is just fine, but the effect engaged now has a continuous digital "farting" sound, for lack of a better term. :P Here's a shot of the topside:
(http://www.songbucketaudio.com/SongbucketAudio/Blank_files/IMG_0460.jpg)
I've got one more 7660, I'll try it, I suppose. I'm starting to think I need to get a totally different IC though, either the SCPA version of the 7660 or a MAX1044.
I'm pretty sure IC3 needs to be an SCPA or you'll have problems.
josh
I went back and found this thread: http://www.madbeanpedals.com/forum/index.php?topic=81.0. Says you can sub a MAX1044 for the 7660SCPA (which I can't find anywhere, not even futurelec). Brian said in that thread that you can also use a TC1044... My local shop has LTC1044s which, after a bit of research, are LINEAR TC1044s, and "Linear" appears to refer to the manufacturer. I just want to make sure it's work the trip before I drive on up to my local shop.
I did find the 7660SCPA IC at Mouser, they've got 'em pretty cheap (individuals at $1.08, between 10-25 qty. $.90, group buy, anyone??). I'm trying to determine if I should order the SCPAs from Mouser or if I can just head up to my local shop and pick up those LTC1044s...
It appears from comparing the datasheets that it may work... It's worth a try at least.
You can buy the max1044 from small bear.
http://www.smallbearelec.com/Detail.bok?no=244
I'd love a "local" shop in my area. There pretty non-existent in the Philly area. :-\
josh-
Quote from: gtr2 on March 21, 2011, 03:22:57 PM
It appears from comparing the datasheets that it may work... It's worth a try at least.
You can buy the max1044 from small bear.
http://www.smallbearelec.com/Detail.bok?no=244
I'd love a "local" shop in my area. There pretty non-existent in the Philly area. :-\
josh-
Yeah, it's nice to have a local store, it's where I get most of my caps & resistors these days.
I just got back from picking up the TC1044's. Threw one in, still no change from the gain pot when plugged in, but I also don't have the diodes in there. Going to check the values on the ICs again...
***EDIT*** Some success, the values are now where they should be. But again, still not getting any change when turning the gain pot, which seems very strange to me. Even without the diodes in there, methinks the gain pot should do
something...
???
Quote from: pauloman80 on March 21, 2011, 03:43:41 PM
Quote from: gtr2 on March 21, 2011, 03:22:57 PM
It appears from comparing the datasheets that it may work... It's worth a try at least.
You can buy the max1044 from small bear.
http://www.smallbearelec.com/Detail.bok?no=244
I'd love a "local" shop in my area. There pretty non-existent in the Philly area. :-\
josh-
Yeah, it's nice to have a local store, it's where I get most of my caps & resistors these days.
I just got back from picking up the TC1044's. Threw one in, still no change from the gain pot when plugged in, but I also don't have the diodes in there. Going to check the values on the ICs again...
***EDIT*** Some success, the values are now where they should be on the ICs. But again, still not getting any significant change when turning the gain pot, which seems very strange to me. Even without the diodes in there, methinks the gain pot should do something... Could it be the pot is bad? It also seems to me that I should hear some kind of difference with the diodes back in there.
???
An audio probe is simple to make and you most likely have the parts to make one.
http://diy-fever.com/misc/audio-probe/
I use the 1/4" jack socket version so I can use a longer cable if needed.
An audio probe is essential to debugging. Follow along through the circuit with the schematic, it will help you locate where your having problems in the circuit.
josh-
Quote from: gtr2 on March 21, 2011, 06:37:35 PM
An audio probe is simple to make and you most likely have the parts to make one.
http://diy-fever.com/misc/audio-probe/
I use the 1/4" jack socket version so I can use a longer cable if needed.
An audio probe is essential to debugging. Follow along through the circuit with the schematic, it will help you locate where your having problems in the circuit.
josh-
Hmmm... does this mean there are things I can do with an audio probe that I can't with a DMM as far as troubleshooting and debugging?
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
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
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?
Quote from: pauloman80 on March 21, 2011, 07:17:23 PM
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
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.
Could you post a pic of your gain pot wiring? It's hard to see in your previous pics.
josh
Quote from: gtr2 on March 22, 2011, 02:18:43 PM
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.
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.
Quote from: gtr2 on March 22, 2011, 03:26:58 PM
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.
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.
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.
Have you tried testing the pots that you are not sure about with a DMM? Then you can rule that out at least.
Quote from: bigmufffuzzwizz on March 23, 2011, 03:15:52 AM
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.
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
Thanks for being so thorough, Josh. Send that Sunking my way! ;D 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.
Could you re-post your voltages for the IC's and gain lugs since you switched the charge pump?
Josh
If your voltages seem correct I think that the problem may be in IC1. Try swapping in another TL072... If that doesn't work at least you can rule it out...
Josh
Quote from: gtr2 on March 29, 2011, 12:17:45 PM
If your voltages seem correct I think that the problem may be in IC1. Try swapping in another TL072... If that doesn't work at least you can rule it out...
Josh
I've already switched out all the IC's, so I don't think it's any of them. I'll see if I can post IC values today, should have a bit of time to do that.
I'm assuming your pedal works excellent in bypass mode...correct? If this is the case, based off only your previous voltage posts. I think your problem lies somewhere in the feedback loops of IC1. The voltage at pin 3 is to low. You could have a problem with an incorrect resistor value somewhere in the IC1's negative feedback loop. You are going to have to go through the painstaking process of reading resistor color bands. There are good color band calculators online or apps for this if you have an iphone. Also double check for cold solder joints (dull looking solder) or where solder may have joined where it shouldn't creating a short. Use a magnifying glass and go slow. Concentrate your search to components between IC1A and IC2A on the schematic. Your solder work looks pretty good but even one bad joint will wreak havok!
Slow and steady wins the race.... ;) Keep at it, you'll get it ;D
Josh
Yes, Josh, you are correct in that bypass mode sounds just fine and dandy. I was afraid I may have ended up with a resistor that wasn't the right value. The stock at my local shop tends to get mixed a little bit from time to time. I do have a bookmark of a color band calculator, found it my first build as Smallbear doesn't frickin' label their frickin' bags of resistors. :P
My solder joints all look pristine, but I'll go over them again. I'll let you know if I find anything weird between those ICs! Thanks, Josh!
BTW, just read this thread (http://www.madbeanpedals.com/forum/index.php?topic=1430.0) and it sounds like the same exact problem I'm having... but I've been over my solder joints with a fine-toothed comb!...
It's good practice to measure your resistors before putting them in the circuit. I don't always do it like I should but for this build I did. It is kind of a pain but this build uses a lot more uncommon values.
Good luck! :)
Josh
IC1 (TL072)
Pin 1: 4.78
Pin 2: 4.78
Pin 3: 1.24
Pin 4: 0.00
Pin 5: 4.60
Pin 6: 4.77
Pin 7: 4.76
Pin 8: 9.49
IC2 (TL072)
Pin 1: 4.86
Pin 2: 4.77
Pin 3: 4.73
Pin 4: -8.34
Pin 5: 4.71
Pin 6: 4.76
Pin 7: 4.67
Pin 8: 16.49
IC3 (LTC1044 - MAX1044 equivalent)
Pin 1: 9.49
Pin 2: 4.88
Pin 3: 0.00
Pin 4: -3.99
Pin 5: -8.34
Pin 6: 0.03
Pin 7: 4.76
Pin 8: 9.48
I also checked all the resistors between IC1A and IC2A, and all the values appear to be correct except for the two 68k resistors that are part of the DPDT switch: R28 is about 34k, and R29 usually goes to 0.00.
Thoughts?
1) If you are checking resistance with a multimeter you need to take one lead out of the circuit or it will read incorrectly. If the color bands on these are correct your most likely ok.
2) Pin 3 on IC1 is still to low.
3) Pin 6 on IC3 should be around 4V to 5V. With a voltage that low it looks like it is shorting somewhere possibly with the D4 pad. Pin 6 is not actually connected to anything, just a solder pad. It's not used in this circuit. If this pin is grounding it bypasses the 7660's internal series regulator to improve low voltage operation. We don't want this. This may be causing your low voltage on pin 3 of IC1.
To find your short. Put your multimeter in continuity test mode if it has one. Then put one probe under the board on pin 6 of IC3, second take your other probe and touch nearby joints. It it beeps you found where it is shorting. Pin 6 should not be connected to anything else in this circuit. If you don't have a continuity beeper. Just use the ohms setting. If it shows 0.00 you've got continuity.
Hope this helps :)
Josh
1.) Color bands look fully accurate.
2.) What should the value be for Pin 3 on IC1?
3.) I'll have to consult my DMM's manual to determine how to get to the continuity mode, otherwise I'll look for 0.00.
Thanks again, Josh! Really appreciate the time you've been taking to assist me on this.
Pin 3 IC1: 3.43V is madbeans reading, mine was closer to 4V
Josh
Quote from: gtr2 on April 01, 2011, 11:14:25 AM
Pin 3 IC1: 3.43V is madbeans reading, mine was closer to 4V
Josh
Gotcha. I should be able to get back to my office tomorrow and check on those points. Thanks.
Well, I haven't been able to pinpoint the problem. Not having a continuity checker on my DMM is preventing me from identifying where there might be an issue. Going to get with my building buddy here in town on Thursday, he's going to bring his MM and expertise and help me figure out why this thing won't fire up properly. Between the time I finished the build and started troubleshooting up to now, he's already built one from start to finish and it fired right up no problem. >:( Here's hoping he can help me get my working before week's end!
A word of encouragement man, I'm only a couple of months in- but sometimes it just happens. I have built 4 sunkings, 3 have fired right up- 1 has made it's way to my pile of shame. I will pick it up again later. I picked these words up from my pedal building mentor. Maybe grab another board and start from scratch. If you get this one up and running- you can always give it to a friend or sell it :)
Well... I'm absolutely stumped. My building buddy came by, and for a full hour we've gone through this thing. Nothing makes sense.
Hey Madbean... you interested in taking a look at this thing and trying to help me figure out what the crap I did if I ship it to you? Holler back. Thanks.
Did you specifically check pin 6 like I mentioned. Something is wrong here.
Yes, I did check it. My friend brought his DMM over and we used its continuity checker to inspect all the specific points discussed thus far in this thread (thanks to you fine smart gents) and also several additional ones he thought to check. According to the continuity meter, everything appears to be as it should be, except for the voltage not being what it should be. No clue. He's at a loss, and I've been at a loss for weeks now. I've got another board, I suppose I could start all over again... argh. At least the wiring is pretty much done, I would just have to reattach it to the new board. Gonna take extra time getting all the parts and making sure the values are as correct as possible.
But I'd still love if someone on here is willing to take a look at this thing.
If the voltages aren't right, there are only a limited number of problems there could be. Either a part is wrong, backwards, or faulty. It's in there. I'm sorry you might be feeling so frustrated, I certainly understand.
Only one project has beat me as of yet. I have solved every problem I've come across, except one where I had to use a new board. I have one project that is currently not working but I hope to get it working. It's perhaps the biggest single project I've every pursued, and I'm not going to be getting another board.
Jacob
What type sockets are you using? It seems like a silly question but I'll explain...
Machine-Pin http://www.smallbearelec.com/Detail.bok?no=100
or
Dual Leaf http://www.smallbearelec.com/Detail.bok?no=144
I've had the occasional problem with the dual leaf version. Once you install, pull out, and reinstall an IC in this type a few times or even once the leafs bend back. I've tracked down some problems with the IC not making contact with a "broke in" socket. Test for continuity between the pins on the top of each IC and the solder joints on the underside of the board. Do this for each pin on each IC.
It's worth a shot if you have this type of socket.
Josh
Quote from: jkokura on April 08, 2011, 03:20:46 AM
If the voltages aren't right, there are only a limited number of problems there could be. Either a part is wrong, backwards, or faulty. It's in there. I'm sorry you might be feeling so frustrated, I certainly understand.
Only one project has beat me as of yet. I have solved every problem I've come across, except one where I had to use a new board. I have one project that is currently not working but I hope to get it working. It's perhaps the biggest single project I've every pursued, and I'm not going to be getting another board.
Jacob
Thanks, Jacob. I know for a fact that all my parts are correct; I've quintuple-checked every single one over the course of this troubleshooting foray. I also know that none of my polarity-critical parts are hooked up backwards, and the pots are also wired up properly. I had a brief moment yesterday where I thought I did it wrong, but I didn't, much to my relief and frustration (relief because it was right, frustration because I still haven't tracked down the issue).
It is certainly possible that a part is faulty, but we haven't been able to track that sucker down. I gotta say, seeing Josh's post right after yours regarding IC sockets and knowing that I ended up with IC sockets that look kinda "bargain bin" in comparison to the machine-pin version, it's very possible there's an issue with the sockets I used. Pin 6 on IC3 and Pin 3 on IC1 are still not what they should be, and we followed the entire VB trail to figure out if Pin 6 on IC3 was grounding, and it's not. We checked the continuity of the circuit from the input all the way through the negative feedback loops of both halves of IC1, and we checked the entire charge pump circuit. Everything seems normal except for those two particular values.
That leaves me with four options as to why it's not working:
1.) The board is bad/has a bad trace/is being a big fat stupid doo-doo head;
2.) One or more of the IC sockets I used are bad as Josh explained in his latest reply,
I'll still need to do a continuity check between the IC pins and their solder joints to determine if that's it (thanks for the suggestion, Josh!);
3.) There's a ridiculously obvious/easy/simple reason other than the ones submitted thus far that we simply keep glossing over and missing and will feel incredibly embarrassed/stupid for missing, but we'll do so while playing through the pedal with the pots all fully dimed;
4.) There's a infinitesimally obscure and bizarre reason other than any other explanation submitted thus far that we haven't uncovered for whatever reason and would be perfectly understandable if we didn't figure it out until wayyyy after the fact.
Conclusions: I'm going to do a refresh of my parts and start building another one with the other board I have, checking and double-checking the values of every single part before populating it onto the board. Speaking of which, I noticed that nearly every build I've seen thus far has these thick red rectangular caps for C4, C5 and C6. Where can I find those? Took me forever to find the ones I used. Please share!!
If ANYONE wants to take a stab at troubleshooting this existing board for me, I'll detach it from the wiring and ship it to you. I'm 99.999997% positive the issue is with something on the board and has nothing to do with the wiring.
***EDIT: I'm remembering something odd we encountered yesterday that leads me to believe I might have installed crappy IC sockets. We removed all three ICs when we started troubleshooting, my friend wanted to take them totally out of the equation on our first go. Upon putting them back in, we discovered Caps 19 & 20 got really hot. IC3 wasn't quite as hot, but was getting there. Methinks the socket might be crap like Josh explained. I've been successful so far at carefully removing parts from the board without damaging or lifting the solder pads, so I think I need to get some better IC sockets from my friend here (he snatched up all the good machine-pin sockets from our local electronics surplus store, the hoser ;D ) and replace the one that's holding IC3 to the board. Might not be until next week, but we'll see.
Hopefully you'll get it working. Here are my opinions in a different order than asked in your post.
2)It's not that the sockets are bad per say, it's just that the leaf type isn't good for a lot of swapping. You can however get some sort of small tool in there and bent the leafs back if you find this is your problem. Desoldering sockets is a pain. You have to destroy the socket on the top so you can isolate each pin to remove. I'd opt for bending back the leafs if this is your problem and not replacing it unless you have no other options.
1) The board being bad isn't even an option to consider...
Conclusion) You may need a different IC in IC3. This build seems very picky with the charge pump (IC3) This could be the problem. I would try the ICL7660SCPA. I believe you have a comparable substitute right now? Go with what is verified at this point.
Josh
I hope I can get it working as well. I started work on this thing months ago. Meanwhile, my building buddy has built his own (which fired right up) as well as about 15 other pedals, including one he redesigned himself based on a Landgraf Tubescreamer clone. Sheesh.
Responses to your opinions:
2.) I don't even know if the ones I have are the leaf type, but then again, I don't know how many different kinds of sockets there are. The ICs go into each socket pretty smoothly but very securely, and they appear to fit nice and snug. If removing the socket is that difficult I don't think I want to go that route, especially considering how tightly Madbean was able to condense the layout. I'd wreck the components surrounding the socket. Not worth it.
1.) I didn't rule out the board being pad for two reasons: first, there's been a total lack of any other explanation for the problem up to this point; and second, my building buddy has encountered bad fabbed/manufactured boards before, and he's been building a lot longer than me. In spite of the fact that Madbean (as well as you and a good portion of the other members of this site) is a veritable genius compared to me and I love what he's done for the building community and that he's the man, mistakes happen in the manufacturing process.
The LTC1044 is the closest comparable substitute I currently have for the charge pump. I originally couldn't find any 7660SCPAs, so I got 7660CPAs instead and wasn't aware they wouldn't work properly until I put them in and got the high-pitched squealing, which was the first issue I discovered when powering up the build. It's very possible that having the wrong charge pump may have fried something else, but I've replaced the TL072 in IC1 twice since switching to the LTC1044 (which according to the build doc is an equivalent substitute for the MAX1044 as long as I sub a 9V Zener in place of the 12V Zener at D3, even though I tried both and it didn't seem to make a difference either way).
I think the main conclusion I can reach is this: the signal just doesn't seem to be getting the clipping it should through IC1, and it appears to be bypassing D1 and D2 entirely. It's almost as if it's skipping that entire part of the circuit and is going straight from C6 to the junction at Pin 2 of IC2, because Tone and Volume are both performing as they should, which would be great if this were just a boost pedal with a tone circuit. :P The signal path from Input to Pin 3 of IC1 all has the right continuity and appears to have the right voltage until it actually reaches Pin 3, where the voltage is barely half what it should be. Looking at the schematic, I don't quite understand how Pin 6 of IC3 would cause Pin 3 of IC1 to act strangely, but then again, we haven't been able to determine why Pin 6 of IC3 isn't showing the right voltage either. If I can get my hands on some SCPAs and put them at IC3, I'll be back to the verified parts list. Then, who knows? Gotta try it. But I need to find those friggin' elusive 7660SCPAs! No idea where to find them, and I have searched exhaustively both online and locally.
The only other thing I can think of is perhaps the 68n caps I have are bogus or mislabeled. Maybe their value is much too high and there isn't enough signal getting to the rest of IC1. But, I don't have a meter to check their values; it seems to me I'd see incorrect voltages in more places than just two pins on two separate ICs; and I don't see how it could explain the wrong voltage on Pin 3 of IC1 as the cap comes after it in the circuit. Thoughts? Where do you get your 68n and 390n caps from? Those were the caps I had the biggest amount of trouble getting my hands on.
If switching to the verified IC3 and replacing those two 68n caps fixes the problem, SWEET. If not, well, I have no idea.
How about this:
http://www.mouser.com/ProductDetail/Microchip/TC7660SCPA/?qs=iPotdFlfUx98hlix9UcWJA%3d%3d
I got lucky at futurlec and I got a 7660scpa but I wouldn't go that route. It's not labeled as a scpa on the website, just lucky... Unfortunately I only ordered one for some reason or I'd share. :)
68nF take your pick, you just need to convert to uF to find them
http://www.mouser.com/Passive-Components/Capacitors/Film-Capacitors/Polyester-Film-Capacitors/_/N-5g7w?P=1z0wq35&Keyword=capacitors&FS=True
Conversion chart http://www.justradios.com/uFnFpF.html
Josh