Dirtbaby Voltages..just checking, and need help trouble shooting. SOLVED

[blearyeyes]

DOCS:
http://www.madbeanpedals.com/projects/Dirtbaby/Dirtbaby2015.pdf
REV "0"
I have re-flowed suspect solder joints. (probably could find more)
Audio probed from input to IC1. Level drops to very low after R2 220k resistor.
It goes to IC1B and the schematic states pin 7 as input. No Audio there.
(see voltages below)

Voltages are all marked IC1 just checking that they are actually
IC1 IC2 IC3 IC4 left to right.

Chips 2 through 4 match doc voltages.
IC1 seems off...

Voltages for IC1 @ 9.3v regulated linear supply.
Docs    Mine
1.6       6.3   
2.93     4.1 to 5.3 varies
2.93     4.5 to 5.2 varies
0          0
4.24     4.3
4.26     556mv
4.24     7.5
8.4       8.89

Strange behavior: intermittent output appears as overloaded distortion. Like it's being pushed through a bad solder joint or component. Crunch Crunch with beat of music. Then nothing.

Changed out all the TL062 audio chips.

Turn Feedback up all the way and noise begins to run away.
Echo seems to be operating and speed control works.
Just no input passed through unless as mentioned above random bouts of distorted loud overdriven crunchy-ness..
Then nothing. 

Bypass works

Any ideas are welcome!

[madbean]

Hmm, that's a tough one. If you are working on the Rev.0 board, did you omit R40 and R41?

[blearyeyes]

Yes they are omitted and the tails pad is jumpered.
I bought it populated so who knows. Probably not a good idea.
I'll go through the power leading to chip one.
Also get screaming oscillation from some pins on IC1 and 4. (I think..not at workbench)
Document later..

[madbean]

Maybe a pic of the topside of the PCB. Let's have a look at the parts.

[jighead81]

Here's the board I sold to dan and this is what it looked like when it left here, but with different IC's.  I swapped a lot in and out trying to get rid of the hiss.  Same board I posted about in the tech help thread trying to get rid of the hiss and white noise.  It worked fine when it left here (except for the noise). Hope this helps? I don't have any other pics of it

[blearyeyes]

I'm sorry this is not a picture of what was sent to me. The pots and switch were un-soldered and came out before shipping and I replaced them. there was also caps that were socketed C9-10-13-19

Real ugly picture of board:
https://www.dropbox.com/sc/6a1a9jkdwks5uqj/AABnFJFB-RpO0IeVcbQEvjzsa

Sorry I'm having trouble posting pics...

I replaced the socketed caps with original values.
the device makes distorted output around 9v and anything below and above there is silence.

I was told the device was running fine at 18 volts..  if run at 18 volts would any components be prone to failure like the voltage regulator for 5v..?

Daniel S.

[MAO]

FWIW increasing C13 to 47n had the biggest affect on reducing hiss in my build. I had noticed this cap value was much higher than the Dirtbaby's in a few other designs, such as Deep Blue Delay, Multiplex and Neptune Delay.

Keep in mind, this cap changes may take away from the original intent of the Dirtbaby
Sounding like the DMM, I don't know but my main goal was to reduce the hiss and C13 seems to be the answer.

Also, I had already changed C9 & C10 to 2n2 and C8 to 4n7. Those changes didn't seem to make that much of a difference with the noise, or maybe better said I still wasn't happy with the noise level until I increased C13.

At some point I'm going to put C8,C9 and C10 back to stock values and see if increasing C13 alone is enough to tame the hiss.

[jighead81]

yeah I didn't send it out with the board mounted pots and 3PDT, I thought those would be easy enough for someone to replace and save room on shipping, since there were 3 other boards being sent with this one. 

Brian said he wanted to see the board and check out the parts, I thought this would help but it's the only pic I have.  Better than nothing.

Dan, have you checked continuity between the "de-soldered" areas to the next component?  That would tell us alot right there. If you think there's a pad lifted or something, might be a good place to start.

And this board was sold to you cheaper than buying a brand new board, so if you'd like to send that one back to me so I can get it working again, I'll pay shipping both ways.  All the boards I sold you came out to less than the price of a new board.  Or I'll give you a refund for the board.  I sold it so cheap so someone could mess with the PT2399, because I was having such a hard time with the hiss, just like I stated in my listing. 

[madbean]

At this point, considering how much trouble this particular build has caused two people, why not just send it to me to look at. Not something I generally do but my curiosity is piqued on this build and why it seems to be so problematic.

[jighead81]

That sounds awesome Bean, I'd like to know too.  Maybe I had a funky value in there to start with? Maybe that's where the hiss was coming from and that's what could be giving Dan problems?  I honestly have no idea.  Dan, let me know the shipping to bean and I'll pp ya.  Sorry guys, I guess I should've just went with my original plan and tossed it 😞

[madbean]

Nah, never give up. It's just a problem to be solved one way or another (well, okay sometimes that includes tossing it and starting over but we aren't there yet).

[blearyeyes]

it's all cool. I certainly could have messed something up. 
Checking the continuity is a good Idea.
Hey Brian PM me your address and I'll send it out with much appreciation.
Just don't tell anybody so it doesn't turn into a regular thing...

[jighead81]

Man I just looked at your pic, all that brown/orange stuff around the new solder joints (bad around depth pot pads and c/v switch) is dried up burnt flux.  Sometimes cleaning that up can help out big time.  There could be a solder ball or some tiny strand of wire hidden in there just right, that could've flowed around other components.  Just a dab of alcohol on a soft brush will usually do it.  Don't use your toothbrush, lol.  Also J2 looks suspect, may need to be reflowed.  Just a couple things I noticed right off hand, and trying to save the bean a little time.    This thing has just got me super baffled

[blearyeyes]

I found the issue. A lifted pad on the wiper of the level pot on the solder side. 
The board doesn't look as bad as the picture. The color is shifted to the yellow for some reason which makes the rosin stand out. I do have to clean it off though. Thanks for the help. It took 5 minutes to get it up and running after the thought of continuity checking the pots so thanks bro!

Now I have to upgrade my simple tester speaker so I can hear the noise you were talking about.  Well at my age I have built in noise filters in my ears as the top end slowly fades away! HA! Not to mention the cymbal crashes from my brothers Zildians over the years!

The PT2399s are notorious for noise but I have a ton of them to test with and hopefully I can find one that is quite enough.

Cheers!

Thanks again for the great deal and the help!

And thanks Brian for the generous offer!

Daniel S.