How can I disable the capacitive touch sensor on an old Bluetooth earbud for a PAM8403 wireless speaker project?

[alex32]

I'm working on a project to convert an old Bluetooth earbud into a wireless speaker by connecting it to a PAM8403 Class‑D amplifier. The earbud’s capacitive touch sensor (ametal pad in the top right corner, which normally lets you pause/play or trigger Google Assistant) is causing problems—it activates unexpectedly when I connect the PAM8403. I don’t need the touch functionality for this project.

What I've tried so far:

• I attempted to load the sensor by placing 4 Ω resistors in parallel, but that approach didn’t prevent the false triggering.
• I suspect the issue arises because the amplifier’s switching or grounding effects are altering the sensor’s electrical environment.

My questions are:

1. Is there a recommended hardware modification (such as adding a pull‑down resistor, shielding, or cutting the sensor’s PCB trace) to effectively disable the capacitive touch sensor without affecting the rest of the audio circuitry?
2. Are there any best practices for isolating or filtering the sensor inputs when repurposing earbuds for a different function?

Any insights, schematics, or similar project experiences would be greatly appreciated!

[gilshultz]

@alex32

old Bluetooth earbud

What is it? Do you have a model number? Who made it? There are many variations of what you are describing.

[alex32]

The brand is Solix but it's just a generic cheap Chinese product

[alex32]

I don't think the model really matters here, I'm just trying to isolate the pin from interferences or completely remove it

[gilshultz]

Before cutting the trace try a pullup resistor and if that does not work try a Pulldown. Something in the 1K per operating volt would be a good starting point. The Idea is that the resistor will desensitize the capacitance capability by lowering its impedance.