Sunking problems...

[gtr2]

Could you re-post your voltages for the IC's and gain lugs since you switched the charge pump?

Josh

[gtr2]

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

[pauloman80]

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.

[gtr2]

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 

Josh

[pauloman80]

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.  

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 and it sounds like the same exact problem I'm having... but I've been over my solder joints with a fine-toothed comb!...

[gtr2]

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

[pauloman80]

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?

[gtr2]

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

[pauloman80]

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.

[gtr2]

Pin 3 IC1: 3.43V is madbeans reading, mine was closer to 4V

Josh

[pauloman80]

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.

[pauloman80]

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!

[sprayfe]

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

[pauloman80]

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.

[gtr2]

Did you specifically check pin 6 like I mentioned.  Something is wrong here.