Common troubleshooting methods for multimedia speakers

This article introduces some common troubleshooting methods of multimedia speakers:

When there is no sound from the speaker or only one speaker, you should first check whether the power supply and connecting wire are connected properly. Sometimes too much dust will often lead to poor contact. If you are not sure whether it is the sound card problem, you can change the sound source (such as connecting a walkman) to determine whether it is the problem of the speaker itself. When it is determined that the speaker itself is the problem, check whether the speaker voice coil is burnt, whether the speaker voice coil lead is open, whether the feeder is open, and whether it is properly connected to the amplifier. When the sound from the speaker is relatively empty and the sound field is slack, pay attention to whether the left and right channels of the speaker are connected reversely. You can consider transposing the two sets of audio cables. If the sound of the speakers is low, you should focus on checking whether the quality of the speakers is inferior and whether the phase of the bass speaker is reversed. When the speaker has obvious distortion, you can check whether the adjustment degree of bass, 3D, etc. is too large. In addition, the speaker voice coil is skewed, the speaker core is deviated or there is debris in the magnetic gap, the speaker cone is deformed, and the amplifier feeds too much power to cause distortion.

When there is noise in the speakers, the source of the noise should generally be determined first.

1. First, test whether the speaker itself has noise on the recorder or radio. If there is, the speaker itself can be replaced or repaired. The problems of the speaker itself are mainly caused by the cracked speaker cone, the crack of the speaker joint, the loose back panel of the speaker, the speaker frame is not fastened tightly, and the speaker surface net is too loose.

2. Change the sound card to another slot and try to stay away from other cards, such as graphics cards, modem cards, network cards, etc., especially the graphics card, which has the strongest interference and may interfere with any card including the sound card.

3. Unplug the audio cable on the sound card to test. If there is no more noise, it means that the noise is caused by the audio cable. You can change the audio cable or replace the sound card.

Here are a few examples of repairs.

Example 1: Shockwave speaker repair
Trouble phenomenon: A pair of shock wave antimagnetic speakers with a rated power of 30w, and the speakers suddenly have no sound during use.
Fault analysis and treatment: First, check the appearance of the speaker, and no abnormality was found. When the power is turned on, a buzzing noise can be heard, which indicates that the speaker of the speaker is not burned out. I touched the back cover of the speaker and found that the back cover was getting hot gradually. Because the back cover of the speaker is also used as the heat sink of the power amplifier integrated block, it is preliminarily determined that the power amplifier integrated block of the speaker is damaged. Cut off the power, open the back cover of the speaker, observe the power amplifier circuit of the speaker, and find no signs of abnormality in the circuit, capacitors, resistors and other components. Turning on the power again, it is found that in addition to the power amplifier integrated block being extremely hot, the bridge is also extremely hot, and it is preliminarily judged that the power amplifier integrated block may be damaged.

Replace the electric bridge, and remove the solder on the four pins of the electric bridge with a soldering iron and a tin sucker. After the replacement, the power is turned on and the fault is still found; then the power amplifier integrated block is replaced. The TDA1521 power amplifier integrated block has nine pins and is densely arranged, so its disassembly is more complicated. First, remove the screws on the integrated block of the power amplifier, and then slowly remove the solder on each pin on the integrated block; when installing, pay attention to not too much tin on each pin, otherwise it will easily cause phase The adjacent pins are short-circuited. When attaching the screws of the integrated block, pay special attention to tightening, so that the integrated block is tightly combined with the back cover of the speaker to achieve a good heat dissipation effect. After replacing the integrated block, the fault is eliminated.

Example 2: Noise cancellation by microphone
Symptom: When a compatible machine is connected to the microphone, various noises appear, including the noise of the CPU fan, hard disk, and CD-ROM reading.
Fault analysis and processing: First, let's analyze the reasons that cause the noise of multimedia computers to be roughly as follows.
1. If you do hear the noise caused by the hard disk, optical drive and CPU fan, it may be that the performance of the filter circuit of the motherboard and power supply is poor and cannot filter the interference signals generated by the hard disk, optical drive and CPU fan. Shortening the IDE cable and the CPU fan power cable can reduce the impact of the corresponding equipment. You can also try a different power supply.
2. The connection between the microphone and the sound card does not use a shielded wire or the shielded wire is poorly grounded. The external high-frequency interference signal from the microphone input will cause noise. In this case, the noise should disappear after unplugging the microphone. If it is caused by connecting the microphone, use a shielded cable if you don’t use a shielded cable: If a shielded cable is used, use a multimeter to check whether the metal shielding layer of the shielded cable is connected to the chassis to eliminate the influence of poor grounding . In addition, the signal line from the sound card to the active speaker should also be shielded and grounded.
3. Use the "drawing" command of "Accessories" to open a high-color graphic, cut a piece, and drag it quickly with the mouse. If you can hear the "swipe" sound when dragging, it is due to the motherboard, Due to the influence of high-frequency radiation generated by the display card, insert the sound card in the expansion slot far away from the display card, and shield the sound card with an aluminum shielding cover and ground it (pull the box) to reduce the influence of high-frequency radiation.
4. Check the connection between speakers and sound card. ALS007 sound card has two audio output sockets, namely Line Out and SPK Line Out sockets to output unamplified audio signals (high impedance) for connecting active speakers or amplifiers; SPK sockets Output audio signal (low impedance) amplified by the built-in amplifier of the sound card for connecting passive speakers or speakers. If the input line of the active speaker is plugged into the SPK socket by mistake, the distortion of the audio signal (including the noise signal) caused by the double amplification will cause noise due to the impedance mismatch.
If you are still unsatisfied after taking the above measures, you can consider changing to a sound card. If it is indeed the fault caused by the sound card, you should check the electrolytic capacitors C4 and C20 next to the ALS007 chip on the sound card. If the capacity of these two capacitors decreases, it cannot be filtered. In addition to low-frequency noise, a small capacitor of 30-300pF in parallel at both ends can filter out high-frequency noise.

Example 3: USB speakers cannot play audio CDs.
Trouble phenomenon: A newly-purchased USB speaker, the others are normal, but the audio CD cannot be played.
Fault analysis and processing: This is because the CD-ROM players in many computers do not support the direct use of speakers to play the digital audio in the CD. Therefore, before using USB speakers, be sure to see the compatibility of the CD-ROM drive.
After installing the USB speaker as required, you can enter the "Control Panel", then enter the "Multimedia Properties" window, and select the newly installed USB speaker as the preferred audio playback device. In addition, you should select "This CD- ROM device can play digital CD audio" option. If the option does not appear or is grayed out, it means that the CD-ROM drive does not support digital audio.

Example 4: There is noise every time the speaker is turned on.
Trouble phenomenon: After a computer has been used for a period of time, the speaker will be noisy every time the host is turned on.
Fault analysis and processing: First replace the speaker. If the fault persists, it means that the fault is not in the speaker itself. After replacing the SRS, the noise is eliminated and everything returns to normal.
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