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EEVblog 1605 - Chasing Fart Noises - JBL Charge 3 "Repair"

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EEVblog:
Dave is chasing fart noises in this JBL Charge 3 waterproof speaker.
A teardown, and powerup on the bench to find the mysterious fart noises.
Will it get repaired, or will the fault do a Harold Holt?

00:00 - JBL Charge 3 Waterproof Speaker Fault
02:17 - Teardown
07:13 - Drivers
08:16 - Passive Radiators
09:58 - The Case Moulding
10:46 - Main PCB
11:36 - Under the microscope
15:30 - What's this Power Rail doing?
18:07 - Power Rail Capture
20:16 - Are we chasing a red herring down a rabbit hole?
20:56 - Trying to capture the fault: Oscilloscope vs Microphone
22:22 - The Fault has done a Harold Holt

JanWiesemann:
I’ve been having the same issue with my speaker as you where having. I didn’t think it was a electrical problem. Since I wasn’t in the mood for a repair I’ve already placed my speaker on the trash pile. Your video inspired me again and I look a look at it. One of the first things I’ve noticed while taking it apart was a speaker. The back magnet was loose and partially separated from the metal cage. I’ve removed the old glue and replace it with new epoxy. My speaker is now fully functioning again.

Psi:

--- Quote from: JanWiesemann on March 14, 2024, 10:58:03 am ---My speaker is not fully functioning again.

--- End quote ---

Did you mean to say "now" rather than "not"?

HwAoRrDk:
I wonder if that anomaly with the output voltage on the boost converter is because the feedback is being actively driven by something else which is not initialised straight away at power-on (and also shut off before power-down). Inspecting the circuitry  connected to the FB pin would reveal what's going on. Because I can't imagine a passive resistor divider producing that result.

Maybe that is why there is a MOSFET switching power from the boost converter to the amp - they knew the flaw with the output voltage surge and didn't want the amp to see power until it has passed. :)

Kleinstein:
The higher votlage could be a thing for a normal and high power mode. As far as I understood Dave the amplfier itself would support a higher voltage and it likely would need more than 5 V to get the full rated power.

A loose Magent, as shown by JanWiesemann, could be the issue, at least with a point to check, while the unit is apart.

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