by Jisu Kim
<First Impressions>
In the first random draw, I got a modem, but I switched to a Bluetooth speaker instead. Not exactly the one I’ve used before, but close enough. The control panel was all placed on the top, which made it feel pretty straightforward to handle. It powered on and the lights came on, but the Bluetooth connection was unstable.
Size : Its dimensions measured about 4 inches in height × 2½ inches in width × 1½ inches in depth (approximately 101 × 63 × 38 mm), and it weighed around 190 g.
Since it had the J@LB logo on the front and text printed on the bottom plate, I was able to get a rough idea of the device. I looked it up first before getting into the teardown. The product featured a transparent housing design, 5W output(Max), a 5V 500 mAh battery.
by the way, I found the J@LC label refers to JLCPCB, a major PCB manufacturer in China. They are widely known for quick and affordable production services, frequently used by DIY makers, engineers, and startups.⇢ https://jlcpcb.com
<Tools>
- Heat Gun
- Side Cutter
- Long Nose Pliers
- Cutter
- Hex Bit (Torx)
<Teardown Steps>
Step 1) I began with removing the tiny screws located at the top corners of the casing. The screws were extremely small, so I used the smallest hex-shaped driver I could find to remove them. Even then, the screws were a bit smaller than the driver tip, so I had to apply some extra force to get them loose.
Step 2) This exposed the button mechanisms behind the control panel. Each external button is backed by a tactile switch soldered directly onto the PCB(board), aligned to match the labeled functions—power, mode, volume +/-, and play/pause. The setup is straightforward: pressing the button pushes directly on the switch, closing the circuit on the board.
Step 3) After removing the transparent casing, I examined both the front and the back. The front held the control panel, while the back was structured to hold the battery.
Step 4-1) On closer inspection of the board, it sits directly behind the control panel. Each external button (Power, Next/Volume + , Mode/ LED, Previous/Volume-) corresponds to a tactile switch soldered onto the PCB, clearly labeled on the board itself.
The left side of the board also shows the integrated antenna pattern for Bluetooth connectivity, (ㄹlike this shape) while the central IC marked with the JL logo (which is very blurry) is the Jieli Bluetooth audio SoC that handles wireless communication and audio decoding.
Looking closer, I also noticed small labels like R##, C##, Q##, FB##, Y#, U#, MAKE # printed next to the components.
For reference, the labels like R, C, and U, which indicate resistors, capacitors, and integrated circuits.
R + number (e.g., R15, R2)
→ Resistor
→ Controls the flow of current. The number means “the 15th resistor,” for example.
C + number (e.g., C3, C14)
→ Capacitor
→ Stores and releases electrical charge, or stabilizes signals.
U + number (e.g., U2, U5)
→ IC (Integrated Circuit, chip)
→ A chip that performs a specific function.
→ For example, U5 is a small audio amplifier chip.
Q + number (e.g., Q1, Q24)
→ Transistor
→ Amplifies or switches electrical signals.
FB + number (e.g., FB2, FB3)
→ Ferrite Bead (noise filter)
→ Reduces electrical noise and interference in the signal.
Y + number (e.g., Y1)
→ Crystal Oscillator
→ Provides a precise frequency (clock) for the circuit.
MAKE1, MAKE4
→ Test points or manufacturing marks used by the board manufacturer for production and quality checks.
Step 4-2) back side of the board
On the back side of the board, I found the LED that produced the flashing lights when the speaker was first powered on. There was also a marking HS-YDG-A37_V1.0 20240129, which appears to indicate the manufacturer and production date, along with Chinese labels for battery +/– and antenna.
At the top edge, the board carried both a USB port and a TF (microSD) card slot. By inserting a TF card, the speaker can play MP3 files stored on the card without using Bluetooth—a feature commonly found in portable Bluetooth speakers.
Step 5) On the back side, I separated the cylindrical battery from the casing. It was connected to the board, and a blue shrink wrap covered the cell. The battery label showed the specs: BJY 14500 500mAh 3.7V 1.85Wh 202412
Underneath it was a very heavy circular magnet attached for structural stability. The board was also connected to a component labeled MX 4Ω3W.
the glue wouldn’t come off easily, so I had to use a heat gun. Many parts had to be separated with considerable force because of how firmly they were glued or fixed in place.
Step 6) The board, the battery, and the MX 4Ω3W were all connected in this way. The battery was fixed in place with metal tape and stickers to ensure a stable current connection with the board.
Finally, I examined the speaker driver. At first glance, it looks like a heavy round magnet, but in fact this part is the core of the speaker. The label MX 4Ω3W indicates that it is a 4-ohm, 3-watt driver, a specification commonly found in small portable speakers.
The driver is made up of three main parts: the permanent magnet on the back, the voice coil (a thin copper wire wound into a cylinder), and the diaphragm (the orange disc on the front). When current flows through the copper coil, it generates a magnetic field. This field interacts with the permanent magnet at the back, pushing and pulling the coil back and forth. Because the coil is attached to the diaphragm, the diaphragm vibrates with it, moving air and producing sound. [https://electronics.howstuffworks.com/speaker.htm]
So even though it looks like just a magnet from the outside, it actually contains the complete mechanism that transforms electrical signals into audible sound.
In summary
| Number | Name | material | role |
| 1 | case | transparent plastic | outer case / cover |
| 2 | control panel | plastic with rubber | external button interface |
| 3 | strap | rubber | for portability |
| 4 | back cover | plastic with metal | |
| 5 | screws (x8) | metal | tiny screws for top cover |
| 6 | LED cover (?) | plastic | |
| 7 | black sponge stickers | cushioned sticker..? | secure the heavy speaker driver |
| 8 | MX 4Ω 3W | magnet + coil | speaker driver |
| 9 | main board HS–YDG–A37 V1.0 (20240129); | metal (includes JL SoC, amplifier, LED, USB, TF slot) | control all connections such as Bluetooth,LED, sounds and ports. |
| 10 | inner center shell(or container?) | plastic | |
| 11 | detached glue | glue | |
| 12 | Metal tape | metal | to connect battery with the board |
| 13 | sticker | paper | keep the tape securely attached |
| 14 | BJY 14500 500mAh 3.7V (blue) + YT 14500 550mAh 3.7V green cover | battery | Power supply |
In arranging the parts, I tried to place everything back in its original position. While organizing, I realized I had skipped two process of photos : the black sponge stickers and the white plastic piece. The sponge stickers were attached to hold the heavy magnet unit firmly in place, and the white plastic served as a cover for the light that came from the LED on the back of the board.
In conclusion… Because the speaker was light and compact, its structure was not overly complicated, which made the teardown enjoyable. As someone who often listens to music, I hadn’t known that magnets play such a crucial role in speakers, so it was exciting to discover that. Even though it isn’t a high-power driver, I could see how the components were arranged efficiently to match its low-cost design. I tried to dismantle what looked like just a heavy magnet, but only managed to chip away at the edges, leaving me wishing I could have seen more of its inside.