1. The speaker wiring is broken or the frequency division is abnormal. After the speaker wiring breaks, the speaker unit does not have a motivation voltage, which will cause silent failure. The frequency division is generally not easy to disconnect, but it may occur failure such as the lead welding of the lead and short circuit of frequency capacitor.

2. The sound coil is broken. You can use a multimeter RX1 gear to measure the speaker to lead the welding sheet. If the resistance value is ∞, you can use the paint of the two ends of the sound of the audio to scrape the copper wire. If the measurement has been connected and there is a "Kazaka" sound, it indicates that the sound ring is broken, and the welded can be used on the wire head, and another piece of lacquer cable that is similar to the sound coil can be welded.

3. The speaker lead is broken. Because the speakers are vibrating frequently, the woven wires are easy to break, and sometimes the wires have been broken, but the cotton core is still connected. This woven wire is not easy to buy, and it can be replaced with a slightly longer soft guide line.

4. The sound coil is burned. Use a multimeter RX1 gear to measure the speaker lead. If the resistance value is close to 0Ω, and there is no "Khaka" sound, it indicates that the sound coil is burned. Before replacing the audio coil, you should first remove the miscellaneous objects in the magnetic gap, then carefully put the new audio coil into the magnetic gap, correct the sound coil, and use the strong glue to fix the upper and lower positions. Later, fill the gap between the sound coil and the paper tray with the gap of about half of the half. It is best to seal the dust cover, put the speaker paper tray up, and use it for a day to use it normally.