Not sure this is the right place to post this but perhaps someone here will have an answer. I have two TVs on both cable and satellite. I have a local Public TV Channel that occasionally has no sound on one TV. Picture is OK but no sound. The sound on the other TV is just fine. I can use the VCR as a tuner and the sound is OK. Another problem I've noticed is when watching the NBC nightly news on a local NBC station via cable, the sound is not sycronized with the speakers mouth. It's OK on the other TV or if I use the VCR as a tuner. This only occurs when on cable and not the satellite. Both TVs are on the same cable feed. Anyone got any ideas what's going on?
The symptom of a cold solder joint. The sound circuitry is good. A good old slap on the TV cabinet should bring the sound back temporarily. The TV heats up and cools everytime you switch it on or off. That causes expansions and contractions and weak solder joints do lift from the PCB, or generate hairline cracks.
If you are handy with a solder iron and willing to poke around the innards open up the back cover, with the power disconnected of course. With the power on again, you should have video and perhaps audio. Use a wood dowel or some non conductive stick to wiggle the wire cabling. If you get lucky the audio cable (or component eg. volume control, speaker connection) cold solder should show up. Take a close look at the solder joints, especially where the plug pins are soldered onto the PCB.
Don't be too nervous about the high voltage. Normal precautions should suffice. If you do get zapped it is unpleasant but you don't see any TV techs with frazzled nerves or burnt hair walking around. In an earlier life servicing computer monitors and equipment I had been zapped only once.
This this how I fixed my TV's problem with intermittent video problems. The top few video scan lines would spread out every now and then particularly when the furnace fired up in winter. I opened up that hernia box quite a few times over the years to locate the fault without success. It was frustrating as I could not reproduce the problem at will, thus bringing that monster box to the repair shop would be pointless. Furthermore all the electronics was on one PCB and the wiring-packaging was too compact to allow meter probes to reach the test points. On the last try, I happened to brush against the cable and the video problem appeared. Jiggling that cable harness reproduced the problem consistently. The rest was easy.
Anything more than locating and resoldering the cold solder joint is probably a shop job. There are hardly any home repair replaceable electronics components nowadays. Ask for a repair estimate first. If your TV is more than five years old it has probably more than paid for itself and not worth repairing. Its cheaper and better to by a new TV.
The feeds are delayed by the process of sending it to the satellite and back, or in coding electronics. So, one is a few seconds (or a fraction) ahead.
There are many problems that could cause it.
It's mostly unpleasant. If you happen to be unlucky, it can be fatal.
We use Comcast cable for TV, Telephone and Internet service.
I have noticed that about once a week, particularly when watching TV "Premium Channels" or "On Demand" programs there is a high pitched "chittering" background noise on the audio, characteristicly like an "automatic level control" system (It increases in level when the program audio is quiet and noticably decreases when, for example, an actor starts speaking.) It's reminiscent of "alternator whine" on an AM car radio twenty years ago.
The noise sometimes persists for as long as 15 to 30 minutes, then it goes away. If I switch the cable box around to to a few other channels when the noise is present, there isn't that background noise on any of them.
Unless I'm really engaged in the program (Like sometimes it's SWMBO who'se watching it, but I'm reading the newspaper in the same room.) that damn noise starts boring through my brain and is hard to "tune out".
Last night we were watching a pay "On Demand" movie and that annoying audio noise was present for about half the movie. I found myself getting irritated at having to put up with it, particularly as we were "paying extra" for the program.
I've called Comcast's customer service about it, but they act like they don't understand me. (Big suprise.)
Anyone else experienced this particular problem, and got it fixed?
I have that on most channels, some are worse than others. My guess is that it is caused by the video signal being compressed for transmission and de-compressed. It takes time to do the compression/de-compression, and they don't bother to keep the sound and video in sync.
If the video and sound both go to the satellite and back, they should be delayed the same amount. I never noticed this (even with satellites) in the days before digitizing video - only after digitization, so I think it is because of that.
The TV that doesn't have sound on one particular station, make sure the audio isn't setup to play SAP. Sometimes TV stations put nothing or some alternate signal on the SAP, which would explain most of your problems, I think. I say that only 'cause you started to toss in too many "other TV"s and it's a bit confusing which ones you're talking about.
The television network has fragmented, and there are now many more ways of getting TV to the end user than there once were. Encoding or recoding the signal to do statistical multiplexing (if you can look ahead several seconds, you can fit n channels into a given bitrate at better quality than if you just encode them all with minimal delay.
This introduces a several second delay.
Sometimes this is counteracted by adding in delays to other signals, to make them happen more or less in time.
A hop to a GEO satellite and back takes only .2 seconds or so. Even 2 hops only adds .5 seconds.
I have two TVs. One works OK, the other one doesn't. They both are connected to the same cable feed. The audio isn't setup for SAP. This problem has only started a couple of weeks ago.
They do. Sound and vision is always in sync on every broadcast channel The problem is that how do you sync different channels.
If someone's listening to an FM broadcast of a sports event, and happens to turn on a satellite TV, there may be a delay of up to around 10 seconds.
Do you delay the FM signal by 10 seconds? And what if there is a digital cable station getting its feed digitally from that satellite, and reencoding. This may add another 5 seconds, so do you up the delay to 15 seconds?
I don't know. For me it seems to vary by channel and may be better or worse at different times. I had the problem with my old house in a different city, and different cable provider too. And I've seen the same problem in motels I've stayed in.
Swap the TV's and see if the problem stays with the TV or stays at that location. 99.9999999% odds are that it stays with the TV. Are you SURE it's not set to SAP? From the way you answer, it sounds like you might not even know what it is.
"...However, the nature of the sync problems TV is having is just the opposite: The video lags the audio. That's because of digital processing.
"There's a long and a short reason for this; you'll be happy to know that I'm only able to recite the short one: The process of digitally encoding and decoding video is more complicated than for audio, and so it takes longer. Running through a number of encoding and decoding processes where it always takes video longer to make the trip than audio, and the problem gets worse.
... Lip sync on the TV station was correct; on the cable channel it was badly out of sync.
...the problem won't get solved unless you insist that it is. Declare war on lip sync problems and get them fixed. "
but one of the devices has to be used before they get out of sync and another at the end to get them back in sync. So would CNN (say) have to use one before the audio and video get out of sync, and then the local cable company have to use one to get it back in sync?
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