Bluetooth Speaker Repair Dead Board Repair X300

For whatever reason, we may have Bluetooth speakers that no longer work. Here we will focus on those where it is impossible to repair the internal circuitry. In this case, the speaker we have simply stopped working. It no longer charges, the charging port does not work, and even connecting it directly to the voltage rails and with another battery, it does not charge.

For our example, we will use the Logitech X300 speaker. Although this model is known to be difficult to disassemble, I invite you to try it without fear, no matter if it breaks or if the outer casing is a little damaged, otherwise, this speaker would be destined to the trash without further ado.

Please read the full Instructable, to select the right circuits for your protect

M38 board receptor for low voltage

Audio Amplifier

Dc-Dc for high voltage

Bluetooth for high voltage

Charging board

Battery

Solder tools

To keep this Instructable of use for any device, I will not go into details of how to disassemble the speaker.

The first step will be to disassemble our speaker, so it is advisable to look for a video or tutorial on how to disassemble the specific speaker.I recommend to simply search disassembly "speaker model" in Google or YouTube, and also, watching the video will help us to know how to work.

Once opened, the second step is to check what parts we can recover from the Speaker. Sometimes, you can reuse the battery or the charging connector (in some cases, these connectors are not on the motherboard, in case they are not recoverable or damaged, we can always replace them).

Now we need to select our receiver for the Bluetooth speaker. Some speakers are low voltage, so some Bluetooth receivers may work without an extra amplifier. However, others are higher voltage(than our battery), so we will need to include an amplifier that has a higher voltage. To know what we need, we can do it in two ways: first we will check if the battery of our speaker is 7.4V, if this is our case, we will need to use an amplifier with higher voltage; on the other hand, if we see that the battery of our speaker is 3.7V we will need to check if it does not have a Step-Up circuit included on the board. In the case of our speaker, that was the case. This circuit raises the voltage for the amplifier stage, so we will also need an extra amplifier. To detect these circuits, you can look for the original board to contain a section like the one in the following photo, where the most recognizable element is an inductor and MOSFET arrangement. If in doubt, you can always do the physical test of the speaker, or get the supply's for the high voltage speaker)

Now it is time to choose the circuits. We need:

- A Bluetooth receiver for audio (in case your speaker is Mono, you can also use a recycled Bluetooth headphone receiver).

- A Bluetooth receiver for audio whit amplifier (in case your speaker is low voltage)

- An audio amplifier ( if your speaker needs more than 3.7V).

- A DC-DC Step-Up adapter, this will allow us to give the required voltage to our speaker to make it sound ( if your speaker needs more than 3.7V).

- A battery charging circuit.

- A battery (this can be recycled, I am recycling an old cell phone battery).

- A plug for the charger (I'm using a USB-C adapter, if your speaker have one and is not damaged you can use it).

- A switch, as we will need a way to turn off the speaker.

Following these drawings, we are going to assemble our circuit. There are two different drawings, one for low voltage and one for high voltage, if you have doubts, remember that the high voltage one will work for any type.

Before soldering, it will be important to present our circuits in the housing so that it is well fixed, we can remove pieces of plastic that are left over or that do not serve us. Remember that this speaker will be revived, so let's work without fear. We must not forget to also present the battery so that this one remains in its place correctly assembled.

Once we have presented the circuits, we will proceed to solder, always trying to keep the amplifier and the Bluetooth receiver as close as possible to reduce the possibility of noise. In this case, I used "L" headers connectors to be able to solder it and keep it fixed. If it becomes necessary or you need something more flexible, you can always use cables. Before fixing it completely in the box, we have to test everything, so we will solder the speakers and turn it on for testing.

As a tip, I recommend to test first with a voltage source, that matches our requirements, to verify that everything works before implementing the battery section, it is a little more work but it helps to eliminate errors.

You can see in the pictures that I used this methodology for testing.

If we are using a DC-DC converter, it is time to calibrate it before connecting it to our circuit, so with a multimeter and a 3.3V supply we will bring the voltage up to 8V.It is always advisable to double check so I, even after soldering it and turning it on for testing, verify that the voltage is at a proper level.

If you don't know what voltage your speaker is, as soon as you hear it start to sound you can stop.

Now we will proceed to fix the circuit inside the speaker, for this I recommend some double-sided tape. Once we fix all the circuit, we proceed to close the speaker, and test it.

Some tips for this:

- Do not hesitate to drill the housing so that both the charger and the damper are in an accessible place, in this case we drilled a little to fit our damper.

- To fix things, we can use a glue based on cyanoacrylate and baking soda. This mixture will allow us to hold things fairly firmly.

Future work:

Another case for which we can apply this method is on a speaker whose circuit was damaged after falling into the water. This speaker is an SRS-X11 that was dropped in water for an extended period of time. The speaker still works, but the circuit and battery are dead, so, with this method, we can save this speaker as well, as this speaker is mono we are going to use the recycled Bluetooth.

If it is necessary to remove the circuitry remember to recycle it and the batteries, you never know when you might need them.