What should I do if IPTV has picture but no sound? The TV is fine, but 80% of the time it is stuck at the audio settings level. It took me three repairs before I found the pattern.

Last National Day, my mother-in-law called me, her voice was more urgent than usual.: 「The TV was playing, but no sound came out, and the words were moving. 」After being on the phone for a long time and having no idea, I drove over and took a look - the picture was fine, but the news network host opened her mouth but there was no sound. She watched the mute TV alone all afternoon. This happened to me twice more later.: One time it was the 4K zone in my own home, and the other time it was my mother’s new TV. After three times together, I figured out the problem of "there is picture but no sound".: If the picture can come out, it means that the entire video link is open. The only problem is the sound, which has nothing to do with the signal, broadband, or light attenuation. . This article ranks the troubleshooting order from zero cost to hands-on level. If you follow this step, you won't have to wait for a master 90% of the time.

Arrange three own goals first, and you can eliminate most of them within five minutes.

Don't laugh, my mother-in-law's final answer that time was the first of many mistakes.: The TV remote control looked similar to the set-top box remote control. She took the TV remote control and pressed mute. The mute icon did not appear on the TV (some old TVs did not display the mute prompt). It was as simple as that. So before you change any settings, do three things first:

First, Press the mute button on the TV remote , and then look at the corner of the TV screen to see if there is a crossed-out small speaker icon. Smoothly press the TV volume to above 20 - some TVs look exactly like mute when the volume is set to zero.

second, Press the volume button on the set-top box remote control . Many people don’t know that the box itself has a volume, and that this volume is multiplied by the volume of the TV.: The volume of the box is 0, but the TV is still silent when turned on to 100. Boxes like the ZTE B860A have volume buttons on the side of the remote control. Press the plus sign a few times to try.

third, Check if there is a Bluetooth headset logo on the front panel of the box or the TV. . Nowadays, new TVs and boxes support Bluetooth headset connection. Someone at home used the TV to connect the Bluetooth headset to the TV the night before but did not disconnect it after watching it. All the sound was fed to the headset, and the TV speakers were mute. Go into the TV's settings, sound, and audio output, and see if the output device is "Bluetooth" or an external device. If so, change it back to "Local Speaker." This article is listed very high in Huawei's official support document. This is what I encountered at my mother's house - she used the TV to connect to the Bluetooth speaker once and completely forgot about it the next day.

The second high-risk pit: The audio output mode of the set-top box is incorrectly selected.

After the Oolong queue is finished and there is still no sound, it is time to enter the box settings. The entrances have different names for each brand. ZTE and Huawei boxes are usually in "Settings, Sound" or "Settings, Audio". For older machines, you need to go to "System Settings" and scroll to the second level. There is usually a drop-down box for "Audio Output" or "Digital Audio Output", and the options are probably the following.: PCM (or stereo), source code output (or RAW, transparent transmission), automatic .

Wrong selection of this column is the most technical root cause of "picture but no sound". Source code output means that the box does not decode and throws the original audio stream to the TV as it is, allowing the TV to decode it. . The problem is: The original audio stream may be Dolby AC3 or DTS, but your TV may not recognize it. The TV cannot understand this format, and the picture will be played back (the video stream is open), but the sound will be discarded directly - the performance is mute. This is what I bumped into at my own house.: The 4K zone has no sound when it starts broadcasting, but the normal high-definition channel has full sound. Because the audio of the 4K channel uses a heavier encoding, the ordinary station can still be recognized by the TV with the old encoding.

This rule deserves a separate note: Ordinary channels with sound, 4K or ultra-high definition channels have no sound, 90% of the time it is due to audio format decoding. . The support document on Huawei's official website clearly states that ultra-high-definition channels use multiple audio formats according to radio and television industry standards. In the set-top box settings, switch the audio format to non-Dolby or non-DTS (generally called stereo or PCM), and the sound will return. specific path: Find "Audio Settings" in the box settings and select PCM or Stereo as the format. After saving, change the channel and then change it back to trigger a re-decoding.

By the way, which one to choose between PCM and source code? The answer will be different depending on the equipment at home. If the TV is directly connected to the box and does not have an amplifier, PCM is the most stable choice. The box will be unpacked by itself before being sent out. It can accommodate any TV. ； If you have a power amplifier and soundbar at home that use HDMI pass-through, then it is the source code output, and the power amplifier must really support Dolby DTS. If you are not sure, just PCM first. If you can make sound, then study the difference in sound quality.

third: There is no sound on a single channel, it’s a matter of the audio track

There is also a particularly confusing: Only one or two channels are mute, but everything else is good. This is probably not a setup issue; audio track question. Some channels will have multiple audio tracks - one for Mandarin, one for Cantonese, one for stereo, and one for surround. If the one selected by the box by default happens to be something that your device cannot decode (for example, surround sound is selected by default), this channel alone will have no sound.

The search method is crude but effective: Stop on the mute channel and press the "Channel" button or "Track" button on the remote control (some remote controls don't have separate buttons, just press "Confirm/Information" to pop up the channel information page, where you can see the current audio track). Press the channel button to cycle through a circle of audio tracks, switch to the Mandarin stereo track, and the sound will probably come back. After my mother's TV was replaced with a new one, a local channel was muted for three days. I remotely commanded her to press the channel button four times to fix it, all with one phone call. You can also see the resolution and bit rate on the channel information page, and you can also check the picture quality line. Image quality adjustment article I have written it before, but I won’t expand on it here.

If it still doesn’t work, check the line.: HDMI audio and video are going together, but each has its own way of dying.

After all the settings have been arranged and there is still no sound, it is the turn of the physical layer. One HDMI cable carries video and audio at the same time, but they occupy different pins and bandwidth, so When the HDMI cable is half broken, the message "There is picture but no sound" will appear.」 ： The video signal has high fault tolerance and can still produce pictures even with a little bandwidth. ； The audio data flow is thin and is interrupted first. My cousin's house had a low-end HDMI cable used by a decorator. It had oxidized after two years of use. The picture flickered occasionally and the sound was completely silent. After replacing the cable, everything was fine.

The inspection action is very simple: Unplug the HDMI on the box and the TV and plug it in again. Listen for a click. ； If it still doesn't work, try using a confirmed HDMI cable for comparison. If you have an ARC port at home that connects to a power amplifier, be careful not to plug the box into the port marked ARC - ARC is used to send sound out of the TV (the sound from the TV app is sent back to the power amplifier). If the box is plugged in in the opposite direction, some TVs will cause various problems. This end of the box is plugged into an ordinary HDMI IN port.

By the way, audio's "little trickle stops first" temperament is completely different from a problem at the network layer. The live mosaic is like multicast packet loss, the picture is blurry and the sound is intermittent. I am Mosaic troubleshooting article I have settled the accounts. The picture you have now is clean and there is absolutely no sound. It has nothing to do with broadband or Optical Mode. Don’t restart Optical Mode. Restarting it will be in vain.

ending: A table matches the seats on the five floors

After three repairs, I solidified the sequence into a table, from never doing it to doing it.:

After finishing this list, there are still a few things not covered.: For example, if there is no sound after changing the TV, it is probably because the audio format support of the old and new TVs is different. Go back to the second level and set the PCM again, and you can basically receive it. ； For example, if there is no sound from the power amplifier package, check whether the input source of the power amplifier is selected correctly. That is the issue on the audio side. If there is still no sound after everything has been processed, then it is your turn to call number 10000 - you can say "the set-top box plays with pictures but no sound, and the mute audio output track has been checked." When the master hears this, he will know that you have finished the work on the user side and go directly to the device layer to check. Before reporting a fault, please run the remote diagnosis on Xiaoyi Guanjia by yourself. The story about Butler Xiaoyi I have written how to use it, so don’t let the master’s trip go in vain.

Finally, I would like to add my own lesson.: That time, I asked my mother-in-law to "restart and try again" on the phone. She unplugged the optical modem, re-registered and waited for three minutes. The other end of the phone was still not recovered, and both of us were sweating. Later I figured it out: If the picture is moving, it means that the video link is fully connected. The sound issue is probably due to the settings and cables. You can try restarting the box (clearing the decoding cache). Restarting the optical modem is really useless. . Separating the remote control of the TV box from the remote control of the TV and putting a color label on it is more effective than anything else - my mother-in-law's family now has a small red flower on the TV remote control, and the sound has never been missed since.