I repaired this portable speaker but the Bluetooth is still not working

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
1654482767701.png1654482801183.png

Hi, I have this portable speaker that was broken. It would turn on but would not play any music, so after a few tests I diagnosed the speaker driver was shorted. After a lot of examination I noticed a little amplifier chip was faulty:

1654481028748.png

I bought a replacement and when I had to desolder it, I thought I would be able to remove it manually pin by pin with a tiny solder tip. After a little time messing with it I saw it was way more difficult than it seemed, there was always a trace of solder joining the component to the PCB, and due to "excessive" heat and force I kind of messed up that job. I've seen they do this with a heat gun, but I don't have one, so in a little bit of despair I forgot about the tiny tip and precise job, took my biggest tip and simply tried to remove it pushing from one side (I've seen they do it when removing little R or C), hoping the heat would quickly arrive to the other side so I could remove the whole component. That's what happened, but I ended up breaking 3 tracks, 2 just right at the legs (easy fix) and one completely (all the way to the hole).

Also, I didn't know, may be that's why the precise job did not work, it was soldered under the chip too. So... first question would be...

1. Without a heat gun, how would you remove that component?

Anyways, I successfully replaced it, and finally the speaker driver was not shorted, so I tried to play some music using the microSD card and it worked fine!

I am so happy I
fixed it and I understand to such degree what was going on (meaning I could see the driver was shorted and that was not right). Next question would be...

2. Okay, that's a burnt/faulty component, replace it and fixed, but... why is it burnt in the first place? In other words, what if some other faulty component was causing it to overheat and the new replacement is about to have the same destiny?

Imagine the component you are replacing is $50, and you really don't want to see it "pop" as you turn on the device. Imagine that component was NOT the problem but a collateral / direct damage of the actual problem? In a PCB full of components, how do you distinguish one situation from another?

Now, the thing is everything is working fine, except the bluetooth. The radio / media player / microphone recorder / bluetooth / portable speaker has one MODE key that you press and switch between media (USB or microSD card), radio, bluetooth... Whenever I switch to the bluetooth, the display shows a blinking bluetooth icon but when I search with my smartphone for BT devices, I can't find the portable speaker. I don't have the manual but I believe if the icon BT is blinking, that's pairing mode. I've tried any logical set of buttons, actions, combinations and none do anything different, so I assume it's in pairing mode.

I mean, the problem could be I don't know how to put the portable speaker in pairing mode, but if we assume it is and it's not working, something is wrong with the bluetooth. I don't know if it's the antenna or the BT chip. I've looked all over the different PCBs and haven't found any BT chip, so to start with I don't even know where is the BT chip.

3. The real question of the thread is: can you help me find where is the bluetooth and tell me what can I check to know if the BT should work?

Here are pictures of all the PCBs (also feel free to criticize my repair and suggest a better way):

5.jpg6.jpg7.jpg9.jpg11.jpg13.jpg
 
Last edited:

tepalia02

Joined May 13, 2022
37
Hi there, did the speaker used to work earlier? I mean did you use to control it via bluetooth of your phone etc. successfully? The blue board 268.85Mhz looks more like an RF module to me.

And by the way, can you share a close photo of the part I have marked?moduleallaboutcircuits.jpg
 

KeithWalker

Joined Jul 10, 2017
2,399
As you were asked in post #2; have you had it working in Bluetooth mode before?
When pairing a Bluetooth device to your phone it is usual to start the search on the phone and then activate Bluetooth on the slave device.
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
As you were asked in post #2; have you had it working in Bluetooth mode before?
When pairing a Bluetooth device to your phone it is usual to start the search on the phone and then activate Bluetooth on the slave device.
No, never tried bluetooth with this device, but I've tested all the ways possible and this device never appears in my smartphone. It is that either I am doing something wrong (don't know how to put the speaker in pairing mode) or that the BT antenna is not working.
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
Hi there, did the speaker used to work earlier? I mean did you use to control it via bluetooth of your phone etc. successfully? The blue board 268.85Mhz looks more like an RF module to me.

And by the way, can you share a close photo of the part I have marked?View attachment 268891
Here, I think it's just an ECHO effect chip:
1654615565787.png

I still don't know where the Bluetooth chip is... to check if something is wrong next to it.
 

KeithWalker

Joined Jul 10, 2017
2,399
Are you sure that this is a Bluetooth speaker? It looks more like a multi-media player. We don't know the make and model number so we have no way of knowing what it is,
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
Could the blinking Bluetooth be indicating that it is searching for a Bluetooth microphone?
That would be really weird... I don't have the mic so I can't check, but I'm 99.99% sure it's a normal bluetooth for smartphones. Where's even the BT chip? Does not anyone know?
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
If you give us the make and model number, we can probably verify what it is.
It's a Chinese generic product from 2014 or something, it doesn't have a useful model or name or number, I can't even find the manual. You should stop focusing on the "what if" and try to tell me where's the BT chip or figure why the Bluetooth device does not show up.
 

Ya’akov

Joined Jan 27, 2019
5,995
Is there a part number on the chip in the red box? The part in the yellow box seems to be a Japan Radio Corporation receiver chip, which makes sense for the wireless microphone.

1654681635762.png
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
Is there a part number on the chip in the red box? The part in the yellow box seems to be a Japan Radio Corporation receiver chip, which makes sense for the wireless microphone.

Yes:
1654686871092.png

Also, all the info I got about this device from the internet (first pictures) was because I searched for "multimedia portable speaker bluetooth wireless microphone radio" in Google images until I found my model visually. Here's another picture I found. Apparently, the model is DDL/Deddy B-98, but that must be pretty useless... no way to found a PDF manual at least to check how to put BT in pairing mode, which might be the only problem I got.

1654687656559.png
 
Last edited:

Ya’akov

Joined Jan 27, 2019
5,995
Nope, that’s a KT012 from KTMicro. It is obsolete but it has been superseded by other KT0xx chips, they are all transcievers specifically for application to wireless microphones. So that’s your wireless mic chip.

Does the yellow box chip have a readable part number, it is unlikely to be BT but we can check.
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
I already did a "take a pic of all the chips and search all of them" and could not find the BT chip, but also some of them were unknown. I might just post all of them to make this faster. I'm uploading all the chips...

All this time I was thinking it was an antenna problem, but I read yesterday that BT barely needs a dedicated antenna... the thing that bugs me a lot is that the white cable is soldered to the typical radio antena, and to that antenna a black cable is soldered too, but the other end is loose, so I think that is useless, and that black cable must be somewhere else and may be got disconnected from the PCB.
 
Last edited:
Top