JBL Charge 3 Repair – Part 2

I dropped my cellphone on snow-dusted pavement a few months ago. It quit working a few days later. I took it apart to see if melting snow got inside and caused corrosion somewhere, couldn't find anything anywhere. Unplugged all non-essential cables in case any of the cameras and sensors shorted out, still only got the logo to show up for a second before powering off. Ordered a replacement phone.

After I got done setting up my new phone, I decided to measure battery voltage on my old phone just in case I missed the most obvious thing, I noticed that I couldn't feel the buzzer going off at power-on as usual when I pushed the power button and thought it was dead. When I flipped it over, it turned out it had turned on and finished booting. I left it on overnight only to find out it died at some point before I looked at it again next morning. Still doing the flash logo and die routine. I decided to clip my DMM on to look at battery voltage, pressed the power button and the phone booted normally again.

It hasn't randomly turned off since.

The startup tone is a frequency sweep. It might just always come past the frequency where something was vibrating.

A lot of different suggestions. My personal experience with dynamic drivers making THIS exact symptom, Is when the physical mechanism of their operation is "damaged" either the coil has deformed and rubs, or its not completely attached to the cone correctly and slaps the cone when reciprocating. The impact with the other speaker may have altered some already there damage and gotten whatever mechanical noise was, to stop. if it comes back, try swapping the speakers around. or try a different speaker all together.

I wonder if it wasn't an actual mechanically oriented buzzing, where either some part of the case or physical internal structure was buzzing or bumping up against another part at lower frequencies. This would certainly explain why the symptom disappeared after it was disassembled. Then having sufficiently reoriented and reinstalled the various bits and pieces, now no longer wanting to buzz up against whatever, the fart has passed, so to speak.

Maybe the file that it playes at startup somehow got corrupted so it sounded like that.
Then during the repair you disconnected enough things to resett it back to it's original state.
Even when it's switch off, it's still got power to the standby circuit and stuff,
but when you took out the boards, you disconnected everything so it got reset.

I had a little pocket speaker years ago that developed a sound basically identical to this clipping noise at high volume, and only with high power output sounds like a bass note or drone.
I thought it was the driver and replaced it with another but it persisted. Even when connected to a power supply instead of battery. I didn't have any serious testing equipment so no scoping but it seemed to be an issue with the amplifier circuit.

Not that you need those anymore, but did you try contacting JBL to get schematics or service manual?
At least for their professional range they used to be very helpful with repairshops.

I also thought that it's the Battery because my JBL Charge 3 Battery needs replacing and after 5 Minutes on full volume it starts to Distort and then shuts off a Minute later.

Perhaps, it's a glitch with the software or poor connection.

Maybe it need the connectors to be wiggled about, just how sometimes with a pc unplugging all the drives etc makes it work again.

Dave are you getting the Razer Kiyo Pro Ultra webcamera + you can tear it down? It's rated for the THE BEST web camera on the market. Sony Starvis 2 sensor with AI and no more focus hunting. Looks phenomenal.

Probably that processor module desperately needed a proper cold boot… BTW thanks for the teardown, now I know how to replace a battery in mine…

Part Deux? Where's Part 1?

"the fart flask"

My bet is the Lead-Free solder on the speaker.
Lead-Free is wawaaay less "flexible" / ductile? than good old leaded. Especially on a driver that vibrates ALL its life, crack in the joint are bound to happen, even if they don't lead to a full disconnect. BUT the BASS sound at startup, has the PUNCH necessary to disjoint the terminal > FARTS.
Since all new-age electronics are made without lead, that's my guess. I've seen this happen in some other portable electronics, everything measures fine (stationary on the bench), but in hand (as it's made to be used) in a dynamic setting, it sorta works at 95% quality.

Could have also been a socketed wire, but you saw they were hot-snoted in… IDK 🤷‍♂

I have much smaller JBL, which (couple years ago) was a gift from a known electrical parts producer with their logo engraved (looks more like case with that logo was made by JBL but thats my guess). It have a incredible deep bass, loud and in same time very clean sound – not comparable to other JBL-s, which I had to listen. Maybe its a model thing or it was limited production for mentioned company.

All the hallmarks of a speaker touching the housing sounding distorted.

You're missing the simplest possible fault in this case: "Air sealing failure".
Most speakers function like partially airtight sealed chambers, so there's a lot of rubber and foam seals everywhere.
Especially if the thing is waterproof. And you can make a rubber balloon fart…
It would also explain why taking it apart and reassembling it, might have fixed the problem.

I remember the jbl extreme having circuitry dedicated for measuring the audio signal envelope and adjusting the supply rail voltage, presumably just enough so that it doesn’t clip while also improving battery life at very low volumes.

I wonder if the passive radiator was hitting that wire that is really close to it inside.
My vintage B&O speakers developed a buzzing noise a while back. I took the woofer out and found that the fluffy sound damping stuff inside had slipped down and was pushing the wire for the mid range driver into the path of the woofer.

Thanks for showing how to disassemble this unit, as I got that identical model.
Think mine is about 1 1/2 year old, so no problems yet.
I'm a technology follower, and always buy the older, then cheaper model. That was my best investment, as it's really versatile and has a good bass sound.
I also hate such undiscovered errors. I always want to know the root cause.
Anyhow, I also think it was a problem with the connectors, which was oxidized. Probably it had been one of the higher current connectors, i.e. the right speaker. If it would have been the battery connector, both speakers would have made this blurping sound.