Usually after watching the TV for a while, all of a sudden the TV will give out a large audio whine, and then nothing out of the speakers but noise, kind of like the cable has gone out. The noise is variable with the volume control which leads me to believe it isn't the audio amp itself. After unplugging the TV for a while it works as normal. TV was purchased in fall of 2000.
Any suggestions?
Max
Buy a can of freeze mist. That plus a hair dryer to track down the offending part. I would suspect an audio IC from your description. Bob
It's data corruption that is sent via some broadcasters and basically, causes the micro to start to shutdown but, usually stops at shutting audio down. That's why you can unplug, let the micro reset, then plug it back in and it works. Your choices are to deal with it like it is since I'm sure it doesn't happen often or, find a tech that'll install a work around that will fix it but, disable your closed caption feature.
So let me see if I get this right, broadcasters are sending signals to my television to disrupt programming I am paying for?? I don't follow.
Well, since I opened the door, here's a much better explanation and it doesn't put you any further ahead but, at least you'll understand what's happening:
THOMSON AUDIO DROP-OUT
There has been a situation when in some RCA/GE televisions a low-level, scratchy-sounding noise comes out of the speakers instead of normal audio, or when video is muted. These problems can occur when invalid XDS data is broadcast by television stations and received by certain Thomson television receivers. XDS data is digital information placed within the video signal's vertical interval of an analog (NTSC) television transmission. This data is used by the microprocessor in the television receiver. It may be transmitted from any analog television channel. _________
Explanation of XDS data: In each frame of video, line 21 contains a single stream of data, containing different types of data packets. Field 1 of line 21 contains two captioning channels (CC1 and CC2) and two "text" channels (TEXT1 and TEXT2). All four of these data channels share that 600 cps data stream, and the information is sorted out using packet headers. Field 2 contains a matching set of data channels (CC3, CC4, TEXT3, and TEXT4), and can also contain extended data services (XDS) packets.
The XDS (extended data services) provide information about the current program, TV station, and network. Unlike the caption and text data, they are packets rather than continuous streams of data.
XDS packets include:
Name, length, and start time of current show Type of show, based on a set of category codes Program content advisory (see "V-chip data" below) Network name Station name and number Time of day National weather service warning codes ________
The "Thomson audio drop-out problem" occurs when a broadcaster sends invalid XDS data - that is, data that does not contain truncation packets. There are certain XDS encoders on the market that broadcasters may use that will do this. Thomson television receivers using 16-bit microprocessors (i.e. CTC197/PTK195 chassis) are programmed to decode XDS data by counting data packets. When the microprocessor encounters corrupt data with no truncation packets, the data overflows into memory registers where it does not belong, the first of which relate to the audio processing. When the microprocessor encounters this corrupt data in the audio (or even video) registers, it interprets it as the start of a shut-down, and mutes the audio (and/or video).
When the unit is unplugged and replugged, it empties these registers of the corrupt data.
It is good to know that this problem was resolved in newer chassis designs that use 32-bit microprocessors (i.e. MM101/102 and DTV306/307).
But the vulnerable Thomson televisions will do this as they are receiving invalid data from a station to which the MAIN TUNER is tuned. This is why it is so important to find out what channel, and more specifically, what program the viewer was watching at the time of the anomaly.
The real solution: Broadcasters can upgrade their equipment so that the data they send is valid (includes the necessary truncation packets), so that their signal is always 100% valid, and does not mess up these Thomson receivers. Some retailers have someone assigned to contact suspected broadcasters. Once the customer identifies the program (or commercial) was being watched (including the time of day) when the incident occurred, they should report it to the home service specialist.
A final note: XDS data may be inserted live, or played back on video tape by a broadcaster. It can also show up on a VHS tape that the customer recorded from a previously-aired television program.
Ssshhhh! It's all part of the "war on terror". But don't ask how or why.
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