- Joined Nov 9, 2015
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:
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):