Carmine suddenly very loud

[Bret608]

I boxed this last week and tested it out; sounded great (see build report over in that area of the forum). Tonight is the second time I played it and for some reason it's extremely loud, at least intermittently. With the volume and gain all the way down, there is still sound, like a clean-ish boost. Turn the gain up and its pretty bruising! I also noticed some ground-y sounds when turning the pots. I'm suspecting a dodgy joint on one of the diodes. Any other trees to bark up would be most welcome!

 

[jwin615]

Clippers would be my guess as well.
If you used a Elcap for C5, it could be leaking DC on the tone and output pot. That would potentially add dc offset to the clippers as well

 

[Bret608]

Yep, that one is an electro. Is there anywhere I could look for stray voltage that shouldn't be there? Otherwise, time for a reflow party, I guess!

 

[jwin615]

Leg 1 of the tone pot
Can swap C5 for a film if you see DC on the tone pot. Doesn't have to be 1u, if you're low on stock.

 

[Bret608]

Thank you, I will check that out. I don't think I have a film cap in the ballpark at the moment but would drop one in my next order or grab one at work. A couple of other things to note, which I'm now remembering from when I tested the board outside of the box (and which, at the time, I chalked up to my testing box getting dodgy): 1) I wasn't getting sound at first; it was like things had to charge up or something; 2) I was getting crackle and even some pops/ground-type noise when I moved the pots?

 

[jwin615]

DC on the pots would cause crackle and DC on the output would cause hum

 

[Bret608]

Okay, so I check leg 1 on the tone pot with my DMM. I'm getting 0 up to 0.7mv at most. Let me know if that sheds any light. It does seem like an electro in the signal path may have been a less than optimal choice if film was an option, unless I'm missing something.

 

[falco_femoralis]

post pics

 

[Bret608]

Let's start with this and I'll get the bottom of the board if we get to that point (since I'd have to yank it from the box, lol...):

 

[Chuck D. Bones]

Visual inspection???

 

[Bret608]

The picture may not be a huge value-add, true; I've already checked resistor values, orientation of anything with polarity, that the diodes still have the same fv they did before soldering, etc. Thank you to anyone willing to take a look, though!

 

[Chuck D. Bones]

Have you done a thorough visual inspection under magnification? Every solder joint. Look for cracked traces, debris and solder bridges.

 

[jwin615]

I would go ahead and reflow.
You have very little solder coming through the through holes. Should see if flow at least to the point of flush with the other side of the PCB.