Thursday, 3-October-2024
MP5 player - powering issue
EN
This time, the case is about Chinese MP5 player. That one have TFT screen that can be pulled only by hand. Some simple MP3 , video function.. Nothing so much about it, except it ran fine for one test and then refuse to “rise” up…
After the top was removed here is what stare in my face:
Well not so much parts in it, inst it?
On the right you can see the whole “brain” that control, play and show interface on that device. The parts as I recognize them (not saying i`m right in my thoughts..) are that ones:
1 - processor
2 - EEPROM (with the firmware)
3 - some radio - Bluetooth and perhaps MP3 decoder..
4 - 2.5v regulator
5 - preamplifier or sound decoder (maybe..)
6 - 3.3v reglator
7 - DC-DC 12 to 5 volt step down IC
After connected 12V to ACC and B+ pins and GND to GND , I managed to measure +1.5V over DC-IN pin on the 3.3 and 2.5v regulators.
Next I trace the 5V that ware steady and present to that 220uF capacitor seen the image above. From there following the red line via P-fet it should be going to the rest of the circuit. Unfortunately for me I had only 1.45-1.5v.. The Gate pin had 0.22V and that was it. The blue line show the Gate control line.
So just for test I remove that transistor:
and make a bridge with tweezers so the 5V can flow as expected. That made the player to lid up, which was great.
Nothing else was dead.
At first I though to fit some big ass P-fet there like this one:
but it seemed that I had in my parts storage A19T what is quite close to A79T.
After I solder it on place:
Over the Gate pin I got 5V when player was off instead 0.25, and finally it start working again as it should:
That was here the happy ending. But anyway I would not at all buy something like that, and quite frankly would recommend you do not too..
- bad radio receiving
- some small noise when MP3 was played
- screen must be open by hand
- very thin tracks to the USB`s power pins
- not so reliable components..
By the way, here is the wire size that it was supply with:
That should handle phone charge with about 1-2A , USB stick, player power and 4×15W speakers.. Yeah right..
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