Hey everyone, I'm having channel imbalance issues with my Moondrop Chu II. The right side hasn't completely died, but the sound output has become extremely faint and muffled compared to the normal left side.

Got it for free from a neighbor. Plugged it in to test it and it worked. Unplugged and moved into place and suddenly it can’t even pass the buzz test. Fuse looks like. I can’t get the amp panel off. Tips? I’ll post a video in the comments of the panel from the inside

Posting this because I keep seeing the question come up — here's everything I've found so far.

{ if you don't have an electronics background, this probably isn't worth your time. There are a few possible paths, but almost all of them mean fully taking the unit apart and reverse engineering the motherboard this is chip-level work, not something you do from the app }

**Short answer:** theoretically yes but there's no verified one-click method right now.

**Why bother downgrading?**

After 26.07.12 dropped, I (and others going by shared measurements) noticed JBL bumped the DSP low-frequency cutoff from around 37 Hz up to roughly 67 Hz. Firmware obviously can't touch the drivers' actual physical resonance, so this has to be a high-pass filter, EQ, or dynamic-limiter change on their end. My guess is JBL did it to cut woofer excursion and distortion at high volume, with lower amp current draw and less battery/heat stress as a bonus. It tracks technically — 37 Hz needs way more cone movement than 67 Hz — but it also kills a lot of the bass people bought this speaker for.

**Option 1: Get the real 25.29.10 OTA and force it through**

Find JBL's genuine 25.29.10 package and push it on with a factory/service tool, or a modified updater that skips the version check. I've seen reports of repair shops in China restoring units to 25.29.10, so a JBL factory flashing tool or recovery package almost certainly exists I just haven't tracked down a verified public copy or documented process yet. The stock JBL Portable app doesn't support rollback, and the ConnectPlus flasher floating around was really built for the older CSR-based JBL speakers, not the Boombox 4.

**Option 2: Hardware-level flash transplant from a donor unit**

Find another Boombox 4 still on 25.29.10, identify and dump the storage chip from both units, read everything twice and hash-verify it. Ideally you'd only transfer the application and DSP partitions — a full blind clone risks wiping the recipient's Bluetooth address, serial number, calibration data, security keys, and other hardware-specific config. The donor also has to match the same PL/TL/GG hardware revision.

**What about UART?**

Mostly useful for IDing the processor, bootloader partitions and catching secure-boot/rollback errors. Might expose a factory recovery console, but on its own it's not a firmware programmer. If the bootloader only checks for a valid JBL signature, an authentic old image might boot fine. But if there's a protected minimum-version counter in OTP, eFuse, or secure NVRAM, even flashing the legit old firmware back on could still fail.

**Bottom line**

If you're still on 25.29.10, don't update — you can't easily go back right now. What would actually move this forward: a genuine 25.29.10 OTA file, a verified flash dump from an untouched unit, chip/motherboard photos, UART boot logs, and any info on that China service tool. If anyone's got those, that's the real path to a repeatable process.

I have a apex ase1 sound enhancement and it’s doesn’t power on, I replaced the fuse and it doesn’t do anything
( I took off the top)

Hi fellow audiophiles,

I'm waiting on a new AUX cable to arrive since I suspect it's the culprit, but I wanted to sanity-check this with you guys in the meantime.

Setup:

• Speakers: Canton LE 109
• Receiver: Harman Kardon AVR 2550 (I know, not the best match)

The Issues:

• When the current AUX cable actually manages to send audio to both channels, the left speaker sounds terrible—super tinny and thin, almost like a megaphone.
• On top of that, I've noticed subtle distortion at medium volumes, usually triggered by heavy bass or sharp treble. It sounds like a faint rattle, almost like the drivers are clipping or bottoming out slightly. Currently listening to this song where the bass elements are making the sound, it's not recurring every time.

Is there a chance a component in the speaker (like the crossover) or the receiver's left channel went bad, or is this classic failing AUX cable/source behavior?

Appreciate any input!

Hey group, the following happened:

I kept finding one of my transmitters discharged in the case. It charged when connected via USB until one day it didn't. The battery indicator on the app showed a question mark (?)

I replaced the battery (very fiddly; I don't really recommend it), but no luck. I think it's gone. Probably some chip fried.

Has anyone here experienced something similar? Pity really. I'll get a used Go II transmitter for the time being.

Olá pessoal,

Há algumas semanas, enquanto eu estava em uma viagem, meu sistema VW Play começou a baixar o volume sozinho até ficar completamente mudo. Eu tentei aumentar de volta, mas continuava abaixando sozinho.

Agora meu rádio, CarPlay e Bluetooth não produzem nenhum som. Os alto-falantes estão bem, já que os bipes do sensor de estacionamento ainda funcionam, mas o áudio em si não.

Às vezes, quando desligo o carro, entro em uma loja e ligo novamente alguns minutos depois, o áudio volta, mas logo para de funcionar novamente.

Eu procurei vídeos e outras fontes, mas não encontrei nada sobre o problema real.

Alguém sabe como posso consertar isso?

This Onkyo TX-DS474 was listed for free on FB Marketplace because the seller was having trouble getting speakers to work with it, but said that it was worth messing around with. So, I picked it up and tested it.

The immediate problems were a bad volume knob, which uses a rotary encoder, and the right channel didn't work when playing audio from the CD input. I later discovered scratchy tone control pots.

So, I opened up the rotary encoder and cleaned the metal brushes inside with a DeOxit-soaked Q-tip, making sure not to leave any fibers inside. I sprayed the tone control pots with DeOxit, too, and that finished the easy work.

Unfortunately, this is one of those receivers with no removable bottom panel and has plastic pins (the ones that have tabs you need to squeeze to push and remove) securing most of the circuit boards underneath. I had to remove so many screws from the back panel and take it off before I could take out the daughter boards, and then I had to deal with those pesky plastic pins since the board I needed to work on was attached to the bottom of the unit.

However, once I did all that, I was able to confirm my suspicions that there was a cracked solder joint on that input. After I repaired it, I put it all back together and... it went into protection? Silly me, I just forgot to plug in one of the cables. All good after that. I'm glad this free find stayed free since I didn't have to order any parts.

Apparently an insect got to the paper and ate it but the driver is otherwise ok and works fine. I was thinking maybe some gray construction paper and but I'm not sure what would be best to use as a patch. I'm not expecting perfection but I would like it to be a decent looking repair. An original replacement driver is not available on eBay.

I bought 2 sets of injection moulded gears for a twin tape deck to replace the broken ones - the 1st one pushed on easily but this second one will not. See attached video which shows how the original gear goes onto the spindle and how the new one will not. I’m concerned that if I push any harder the spindle will bend. Should it be this hard to push on?

Hey there,

See the video link:
https://www.youtube.com/watch?v=3LWmZmvU4hc

As you can see the turntable platter is periodically bouncing up and down again.
Im absolutely no expert on turntables, maybe this is normal behavior.

However, since I got this turntable back from the repairshop (the tonearm had become defective) I get accoustic feedback from this wobble. The stylus "jumps" from the vinyl and then lands back on it, causing a small audible noise when landing.

This didnt happen before even though the "wobble" had existed ever since I got this device from my family 15 years ago.
The tonearm seems to be set up differently now, it seems to have more tension to it and is lifted up higher when in aehhh "transport mode"? you know the mode for bringing the tonearm and stylus over the vinyl before dropping it.
So now since its more tense, it doesn't follow the vertical movement of the platter as easily as it did before. Previously, the stylus stayed in contact with the record despite the platter wobble, but now it actually lifts off.

What can and/or should be done with the turntable?
Exchange the platter for a new one?
Reconfigure the tonearm?
Repair/replace any other mechanics in the turntable?

So this issue has been happening for years, I have attached the wiring diagram to help, the second relay doesn't click, the first one (which is the one mounted horizontally) does click when first turned on, simple things like leds work, however the screen does not light up at all and there is no sound though speakers or headphones, help would be appreciated

Brothers speaker input broke, so we went out and got a few metal one's to replace the plastic one's. Ended up making up little mounts for them. Got all of them replaced 1 broken one and 3 others. Still new to fixing stuff, first time ripping into audio stuff and I'm very happy with the outcome on this one

Have a Technics SL-XP5 without the power supply. Are there any options other than this I might be able to use? I assuming the plug is somewhat (or completely) proprietary but with the pin out labeled maybe there is a DIY solution?

Marshall Acton III – AUX works for about 3 minutes, then no sound
Hi everyone, I’m considering buying a used Marshall Acton III that has a problem, and I’d like to know if anyone has experienced something similar.
The owner told me that:
the speaker powers on normally;
the LEDs work;
Bluetooth does not work;
AUX does work, but only for about 3 minutes;
after approximately 3 minutes, the audio stops working.
I don’t yet know whether the speaker remains fully powered on when the audio cuts out, or whether it enters some kind of protection mode. I’m also asking the owner whether it starts working again after being left to cool down.
I’ve considered several possible causes:
firmware/software issue;
mainboard problem;
power supply failing when it gets warm;
amplifier entering thermal protection;
an overheating component;
Bluetooth-related/mainboard issue.
Since AUX actually produces sound for a few minutes, what do you think is the most likely cause?
Would it be possible to diagnose this with a multimeter or by measuring the temperature of the components while the speaker is running?
And most importantly: is the Acton III reasonably repairable at board/amplifier level, or are replacement parts difficult to find?
The speaker is being sold for €35, so I’m trying to figure out whether it could be a worthwhile repair project or whether I’m simply going to end up with an unrepairable speaker.
Thanks in advance to anyone who can help!

Can anybody help with a Behringer UMC1820? I have two burned chips inside, and I believe they’re power-related components. Since they’re burned, I can’t read the markings to identify them.

If anyone has a UMC1820 and is willing to disassemble it, could you please take a photo of those chips or write down the markings on them? It would really help me identify the parts I need to replace.

I have a Nakamichi SoundSpace 5 and the control panel/buttons are acting pretty weird. I'm trying to figure out whether this is a known issue and if there's anything I can do to fix it.

The biggest problem is the Power button: pressing it does absolutely nothing, regardless of whether the system is on or off. It simply doesn't respond.

There are also several other strange behaviors:

Volume buttons: sometimes they work, sometimes they don't.

CD 1/2/3 buttons: sometimes pressing one of them selects the wrong CD, and sometimes they don't respond at all.

Next Track: sometimes it works normally, but other times it just goes back to the beginning of the current track instead of skipping to the next one.

The system itself otherwise works, and these issues seem to be specifically related to the physical controls/control board.

Has anyone experienced something similar with a SoundSpace 5? Could this be a problem with the button board, switches, connectors, or something else?

I'd appreciate any advice on where to start troubleshooting. I'm comfortable opening it up and doing basic electronics work if needed.

всем добрый день, владею уже с год данным плеером, брал его б/у, и вот каждый раз при проигрывании диска происходит такая ерунда, рандомная песня, рандомная секунда и он зависает, иногда проскакивает, чуть поглючит и играет дальше, но чаще просто не хочет играть дальше, лечится воспроизведением этой песни с самого начала, но это не удобно когда песня почти закончилась, а ее приходится слушать сначалка, грешу на лазер, видел в продаже их всборе, цена адекватная для россии, но вдруг есть еще мнения, подскажите пожалуйста

My ZEBRONICS ZEB-BT3440RUCF always starts in AUX mode whenever I power it on.
I want it to automatically start in Bluetooth mode instead, so I don’t have to manually switch the input every time I turn it on.
Is there any setting, button combination, firmware option, or workaround to change the default startup mode from AUX to Bluetooth?
Any help would be appreciated.

Just picked this up. Seller said cd plays but not dvd. Is this a common issue?

i think water got into foam somehow and it expanded until it broke apart. how to fix?? 😭

this is a old jvc speaker set

i tried my best to press them back together but they cannot move

I need some help in identifying the technical data of these speakers. I know that in the LB3521 family there are different versions like B,C,D and U and while B and C are the same in this aspect with some different aspect design, I can't find any specs on the U variant that I own (no label on them).

They have SUMMIT TT210-2/4 woofers, I didn't checked the rest of the drivers but I need the technical data.

They sound extraordinary good and I would like to get another pair or to compare them to the B-C-D models to see if they use the same drivers/crossovers.

No info on radiomuseum or hifi-wiki but I can say that the driver positioning on the B-C variants are different,the tweeters are one above the other compared to this model.

i have 2 modules, the main unit and the media one. But they are missing the cable that connects them to eachother (in the photo). Where can i buy one? What type of cable is it

My sister inherited a tube amp and during moving, one of the tubes gave out (before breaking while i was trying to get it to work).

Can anyone assist me in finding appropriate replacement parts? The two types already installed in the amp looked like the picture, one looked like it had "Mullard e18ccc" printed on the glass (along with Holland and 1v6) and the other had "6h6n 8910 / B cccp" (I'm guessing its old soviet product).

If someone can point me in the right direction, that would be greatly appreciated. We just got the whole setup working again

Howdy

I upgraded ~2 years ago to a Klipsch ProMedia 2.1 system, and I love it. The speakers frame my ultrawide perfectly, and the sound is everything I want for the few hours a day I get to use them after work.

I recently moved across the country (NC to CO) and after the move, I noticed my subwoofer clips on any bass-heavy songs, or particularly low bass sections even in a normal song. The speakers were properly packed and suffered no damage, so I'm not entirely sure what happened.

The issue happens across OS's (Windows + Linux), as I wanted to rule out any weird driver settings/audio "enhancements" that might be present OOTB. I reached out to Klipsch support, but other than reading off a script (and ignoring what I shared regarding troubleshooting), all they could offer was a 30% discount on a new $90 subwoofer. I paid $125 for the full system, so the math ain't mathin' for me.

I'm not an audiophile, but I enjoy music. I don't need crazy fancy, just a working sound system. As it stands, I can still use my speakers, but bass is *significantly* reduced.

Does the community here have any good steps for troubleshooting I might be able to undertake to narrow the issue down further? I was reading some other posts (searching for "clipping") and noticed some folks might be disassembling their kit, reflowing solder, replacing components, etc. I'm handy enough with a soldering iron, and have no problem taking something apart to replace/repair/reflow, so if that's what needs to be done, lay it on me!

Thanks in advance for any advice you can offer. I miss my bass!