Introduction: Fixing Onyx Neo Earbuds (not Charging)
A while back I bought some Onyx Neo Earbuds. They give a pretty good sound and I do like them but recently they decided to stop charging.
Since they were quite inexpensive, at first I thought it was the battery that died due to some poor quality used.
After a couple of testing and poking around, I came to the conclusion that the issue is with the charger from the case itself. It just fails to charge both the battery or the earbuds.
While searching for information on the chip that stopped working, I came across this Russian Forum which discusses the exact same issues I was having and how to fix it. You'll find there some alternatives for repairing this issue.
The damaged chip is an LP7801 and it's not easy to find. I am currently waiting for one that I bought on eBay but I ended up not needing it as a good alternative for it exists by using a battery charger with 5v booster using 134NP chip.
The forum mention this example and its exactly what I am using here
I cannot be held responsible if you damage (even more the device) or get hurt performing any of these steps. Please be very careful when performing all steps always looking at voltages and polarities!
Have fun :)
Step 1: Disassemble the Case
Opening the case is quite simple actually
Start by removing the earbuds from the case.
The first attempt os separating the case from the middle plastic will require a bit of force because you may find a bit of double-sided tape holding the case to the charging plastic.
Step 2: Remove the Battery and Charging Circuit
After opening the case you will have access to the battery and charging circuit.
Carefully remove the battery by desoldering both wires and then remove both screws that hold the charging circuit
Step 3: Prepare the New Board
I failed to take pictures of the preparation of the new board.
In essence, you need to remove both USB ports that it has in order to save space.
Step 4: Prepare Charging Board and Cover to Support New Charging Unit
Before continuing you'll need to find a good spot to get power from the USB-C plug. I scraped a bit of mask from the board on the V+ pin and put a bit of solder there. Will be useful later on.
After taking a look at the original board (and keeping the basic part of the circuit that supports the pins to charge the earbuds and USB-C circuit) its time to mark for the cut. I made a mark and fitted the board again on the case to check that it was ok and that there was enough space for the new one.
Now with the help of a cutting knife or a Dremel cut the circuit board.
After that, with the help of a Soldering Iron or Dremel, cut part of the plastic to allow space for the new board as its a bit wider than the space available. You can slightly trim away the sides of the board if needed and the corners (like I did on mine)
Keep trying to remove a bit of plastic, and fit. Do it in small steps to avoid removing too much plastic and creating a hole to the earbuds side.
Step 5: Now Join Everything Together
Now put two wires in the micro USB side. I chose white for ground and red for positive side.
Turn the board around and put two more wires on the V- and V+ of the bigger USB. I chose white for ground and green for positive.
Now attach the old board that we saved with screws, slide the new board, and start wiring as you see in the picture.
We will use the ground pin where the battery was connected before, and the red wire on the bit of solder we scaped before (USB-C V+).
The other wires (white and green) you connect to the pins of the earphones. In my example the left pin is ground and the right is V+
You can now use a bit of hot glue to hold the new board in place and avoid it sliding.
Step 6: Time to Connect the Battery Again
Now take the battery and put a bit of double-sided tape to hold it to the circuit board.
You'll notice that I have put the battery 180º from its original position and also tuned it around to allow the curvature of the battery to match the curvature of the case.
Now with the battery in place, solder the pins to the corresponding places respecting polarity! They are identified with B+ (positive) and B- (ground)
Be very careful to not plug it the other way around and cause harm for you and for the circuit
Step 7: The Moment of Truth
Now with everything connected start by attaching the USB-C before putting everything in the case.
The light should flash indicating its charging.
If everything is ok, remove the cable and insert the circuit plastic in the case and make sure you ear the clicking sound of the case fitting in.
Plug the power cable again and take a look at the charging hole. It should show it blinking and confirming the charge.
Put the earbuds on the case and they should display the charging light (red ring of light).
Removing the cable should show them blinking and turning red again.
This confirms that everything is working as expected and now the new circuit should last forever :)
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