SOLVED wiper noise. different suppliers. different pedals. what am i doing wrong?

likeyeah

likeyeah

Member
I'm at somewhat of a loss, and wondering what i'm missing.
I did a college search for the problem, but so far i'm still being new and stumbling around so hopefully someone can help me.
I've built 2 pedals so far, a stumble and a transcendence boost, and they both have the same quirk.

- all dirt is being generated by the amp itself, no distortion pedals on the pedalboard
- Both pedals sound as expected when engaged, (no distortion when played clean, etc)
- all pedals are on iso power, there's no hum or other issues.

both pedals exhibit wiper noise when i use the volume knobs at higher gains.
edit- it's a soft rubbing noise like a mic being dragged through fur or something.. no crackles or pops. just the sound of ...movement.


Things i've done:

original pots were amplified parts sourced, replaced with ones from i love my switches.
original electrolytic caps were 'capacitor' brand caps, replaced with nichicon and (iirc) rubycon.
original ceramic caps were 'capacitor' brand caps replaced with vishays
the only caps i didn't change were the film caps, those are kemets.

what am i missing? thanks for helping a noob.
 
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Solution
pbrommer
When you say wiper noise on the volume, you’re meaning the pedal volume/boost, correct?

I was thinking dc leaking to the wiper, but I’m wondering if you’re having issues I sometimes have: forgetting to turn the potentiometer all the way off or on to solder, which causes a burn/jump in the track.

If it’s just with your guitar potentiometer volume, then it might be something with something else. Hopefully that’s a start.
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When you say wiper noise on the volume, you’re meaning the pedal volume/boost, correct?

I was thinking dc leaking to the wiper, but I’m wondering if you’re having issues I sometimes have: forgetting to turn the potentiometer all the way off or on to solder, which causes a burn/jump in the track.

If it’s just with your guitar potentiometer volume, then it might be something with something else. Hopefully that’s a start.
 
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Solution
pbrommer said:
When you say wiper noise on the volume, you’re meaning the pedal volume/boost, correct?
Click to expand...
yes i'm talking about the pedals. its tuner --> stumble + what's in its loop --> transcendence --> amp.
i've tested each pedal by itself also.
pbrommer said:
I was thinking dc leaking to the wiper, but I’m wondering if you’re having issues I sometimes have: forgetting to turn the potentiometer all the way off or on to solder, which causes a burn/jump in the track.
Click to expand...
i remembered to do this with the replacement parts, was wondering the same, so i'd just gotten new ones from a different place... also noted the three second heat window on the data sheet the second time around.. so i just replaced all three out of hand.. no change.
the noise is smooth in the sweep.. so it doesn't sound like there's any hot spots for lack of a better way of conveying it.

how do i troubleshoot dc leakage in these circuits? thank you!
 
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I’d double check voltages, DC before and after the cap coming off the opamps.

Maybe check the opamps and see if they’re good? Only other weird thought is bad jacks or bad cable - or something intermittently weird
 
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pbrommer said:
I was thinking dc leaking to the wiper,
Click to expand...

pbrommer said:
Only other weird thought is bad jacks or bad cable - or something intermittently weird
Click to expand...

this got me thinking, so i scrubbed the pc board with iso again because i forgot to clean it up after swapping the caps and pots for the new ones.
it also dawned on me that when one clearcoats a finish.. wherever the clear paint hits, will be painted. even if it's just overspray. so i sanded the inside of the case around all the holes and also scraped the paint out of the screw holes in the bottom cover just to cover the bases..

the wiper noise is finally gone. Thanks for everyones input.. I'm going to try this on the other pedal too. it's probably the same issue.

edit- the tl;dr is don't rush.. the answer is both reply #1 and #4 in this thread because a) i forgot flux can make dc leakage and b) clear paint can make dodgy grounds to the case that look like bare metal.... but i picked reply #1 because there can be only one!
 
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pbrommer said:
I was thinking dc leaking to the wiper, but I’m wondering if you’re having issues I sometimes have: forgetting to turn the potentiometer all the way off or on to solder, which causes a burn/jump in the track.
Click to expand...
Huh... that's a thing? I have never, ever checked my pots before soldering - I will now! It's odd, I don't think I've ever seen this mentioned here... How often is this a problem I wonder?
 
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I've never had an issue with this happening and I never pay attention to where the pot is turned to. That being said I have read about this on other forums, it could happen when soldering the wiper connection which could heat up enough to burn the resistive trace. IMHO I think the may have been carried over from years ago when it may have been a problem with the older types of heavier duty pots. Current pots have such a lightly made wiper path it simply doesn't conduct enough heat to the contact to cause damage. Again, just my opinion...
 
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