Troubleshooting the Doombutter (w/ fuzz lift)

[whitebread47]

I rocked this before I boxed it and everything worked fine through my test rig.  Wired it up and now it only works in bypass.  I've quadruple checked my wiring and can't find any problems, but I believe something is going awry at the input.  I don't currently have an audio probe, though I need to make one soon.

The entire right side of the PT2399 reads the exact same (3.58v). 

Here are my voltages:

LM386
1- 1.26   8- 1.26
2- 0.00   7- 4.03
3- 0.00   6- 8.08
4- 0.16   5- 2.89

PT2399
1- 7.18     16- 3.58
2- 3.57     15- 3.58
3- 0.00     14- 3.58
4- 0.00    13- 3.58
5- 3.79    12- 3.58
6- 3.58    11- 3.58
7- 0.50    10- 3.58
8- 0.99     9- 3.58

Reg. L78L05
1- 7.18
2- 0.00
3- 8.08


Pics - I had to desolder the input, ground, and +9v wires to get shots of the solder side of the board:

[whitebread47]

Bump.  Just seeing if anyone has a working Doombutter and can tell me if those voltages are off - the 3.58 down the whole right side of the PT2399 seems peculiar to me.

[wgc]

Love the yellow...!

Crazy thought here, but what kind of foam is that under your pcb?  Anti static foam is usually conductive.

Good luck

[whitebread47]

It's double-sided 3M tape.  I've used it in a lot of builds, so it's definitely not conductive.  I didn't know that about anti-static foam; thanks for the tip!

[jimilee]

If you take it back out does it work?

[selfdestroyer]

Here is mine


Here is what I got voltage wise:

LM386
1- 1.3     8- 1.32
2- 9.5m   7- 4.4
3- 0.00   6- 8.9
4- 0.16   5- 1.8

PT2399
1- 5.0      16- 2.53
2- 2.53     15- 2.53
3- 0.00     14- 2.53
4- 0.00    13- 2.53
5- 2.86    12- 2.53
6- 3.6   11- 2.53
7- 0.87    10- 2.53
8- 0.97     9- 2.53

Reg. L78L05
1- 5.0
2- 0.00
3- 8.8

hope this helps. I will keep it open so if you need anything else just ask.

Can I ask how you did the fuzz lift on the Doombutter PCB? I have seen it for the vero but I had issues on the etched Doombutter.

Cody

Edit: I just realized I used the older Doombutter build doc and realized the newer V2 has the lift pads on the PCB. lol maybe its time to make another one.

[whitebread47]

Cody, thanks a ton for posting that picture!  Right off the bat I noticed I have my voltage regulator oriented the opposite way your is.  I hear this can vary from one manufacturer to the next.  Mine's a Fairchild I believe.

My voltages don't seem too off after looking at yours, so I'm thinking either my 7805 reg. is either fried from being backwards or there's some sort of grounding issue with my wiring.

It'll be morning before I can check, but I'll use your pic and go track down the datasheet for my voltage reg. to check the pinout.

While responding I noticed you found the "fuzz lift" version.  That's what I had Haberdasher etch for me - it's an incredibly useful mod on such a wacky pedal.

[selfdestroyer]

Cody, thanks a ton for posting that picture!  Right off the bat I noticed I have my voltage regulator oriented the opposite way your is.  I hear this can vary from one manufacturer to the next.  Mine's a Fairchild I believe.

My voltages don't seem too off after looking at yours, so I'm thinking either my 7805 reg. is either fried from being backwards or there's some sort of grounding issue with my wiring.

It'll be morning before I can check, but I'll use your pic and go track down the datasheet for my voltage reg. to check the pinout.

While responding I noticed you found the "fuzz lift" version.  That's what I had Haberdasher etch for me - it's an incredibly useful mod on such a wacky pedal.

Not a problem.. It was funny really.. I was cleaning up a bunch of pedals and I actually had it next to me on my desk when I read your post and my DMM was like 2 feet from me also.. so it was destiny. lol

I hope it helps you track it down.

[whitebread47]

Not a problem.. It was funny really.. I was cleaning up a bunch of pedals and I actually had it next to me on my desk when I read your post and my DMM was like 2 feet from me also.. so it was destiny. lol

I hope it helps you track it down.

Talk about convenience!

I just took a look at the original Doombutter build doc and the voltage regulator is facing the other way, though the basic layout doesn't seem to be all that different.  All the more reason to check the pinouts I suppose.

[ch1naski]

Your voltage regulator should be showing 5 volts on the output pin, right?

Sent from my Nexus 7 using Tapatalk HD

[Haberdasher]

If it worked un-boxed, it has to be a wiring issue or something grounding out, right?

Can't see any wiring problems from that pic.  I wonder if one of your pots turned when you tightened it on the outside and is now grounding to the case or hitting up against the lugs of another pot.

[Scruffie]

Well your voltage regulator isn't doing its job and your PT2399 is probably dead now, 5V max and it's got 7V on it.

Whether you shorted something boxing or the PT2399 managed to survive for a little while on 7V before popping its clogs I couldn't say.

[whitebread47]

If it worked un-boxed, it has to be a wiring issue or something grounding out, right?

Can't see any wiring problems from that pic.  I wonder if one of your pots turned when you tightened it on the outside and is now grounding to the case or hitting up against the lugs of another pot.

That's a possibility since my drilling left little room.  The pots were in the box when I tested it, so all I did was connect the four test wires directly afterwards - still a chance it's this.

Well your voltage regulator isn't doing its job and your PT2399 is probably dead now, 5V max and it's got 7V on it.

Whether you shorted something boxing or the PT2399 managed to survive for a little while on 7V before popping its clogs I couldn't say.

I only tested it for a minute before wiring it to the jacks and switches, so this is possible.  Going to have a look at it now.

[whitebread47]

Well, I got the Doombutter working now!  I had the voltage reg. oriented the wrong way.  Apparently the ST and Fairchild brand LM78L05's have opposite pinouts.  I'd looked up the wrong brand accidentally, as the brand of 7805's I had consisted of all ST's and one chance Fairchild, so I oriented it right thinking it was a different brand. 

The PT2399 was fried, but now I'm getting 4.99v where needed.  Thanks for the help, guys!

[selfdestroyer]

Awesome.. Glad you got it working.