Klon clone crackles with high output pickups

[yohais]

Hi guys,
I built a Klon Centaur clone.
With Fender single coils it sounds good.
Yet with Seymour Duncan passive humbuckers (medium output) it crackles when I hit the bass strings.
Any ideas regarding a probable mistake I made while assembling it?
Thx.

[kraal]

Hi and welcome to the forum.

In order to help you, we would need more information.
- What clone have you built (kit ? vero ?)
- Pictures (front, back)
- schematics
- measured voltages

Regards

[yohais]

Hi - Thanks for the prompt reply.
I bought a kit on Amazon:
https://www.amazon.com/Overdrive-1590BB-Aluminum-Enclosure-Klons/dp/B0113L1HGA/ref=sr_1_8?dchild=1&keywords=klon+centaur&qid=1600072714&sr=8-8
I have these photos of the pedal I built (I shot one of them just before I closed it).
I'll try to measure voltages later.

[antonis]

HI & Welcome, also..

Try to raise input series resistor value up to 100k, say..
(it's the very first PCB resistor right after IN pad..)

[yohais]

Here is the other side of the board.




I measured some voltages but didn't find something extraordinary...
What specific results are important for this circuit?

Anyway, I heated up a solder joint of one of the silicon diodes which didn't seem to be shiny enough for me.
I have the impression that it sounds much better now. No harsh crackle/distortion.

Does someone here have experience with this design / circuit and common faults?

[yohais]

Hi guys,
Well, I checked the voltages surrounded by circles in the schematic:



Everything was proper, so I guess that the pedal is fully functional.

[antonis]

Amendment: The pedal is potentially DC functional..!! 

To verify full DC functionality, measure also voltages on 5,6 & 7 of U1B and pins 1 & 2 of U2A..

After that, you are allowed to suppose about AC functionality, also..