Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Max Max is offline
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Default Problem with audio on RCA Model G32705 Console TV

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

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Bob Bob is offline
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Default Problem with audio on RCA Model G32705 Console TV

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


"Max" wrote in message
ups.com...
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



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Default Problem with audio on RCA Model G32705 Console TV


Max wrote:
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


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.

www.techdata-kicksass.net

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Default Problem with audio on RCA Model G32705 Console TV


Tech Data wrote:

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.

www.techdata-kicksass.net



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.

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Default Problem with audio on RCA Model G32705 Console TV


Max wrote:
Tech Data wrote:

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.

www.techdata-kicksass.net



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.

www.techdata-kicksass.net



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Default Problem with audio on RCA Model G32705 Console TV


"Max" wrote in message
ups.com...

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.


Ssshhhh! It's all part of the "war on terror". But don't ask how or why.






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