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RCA CTC 203 sound

V

Vince

Jan 1, 1970
0
Hi!
I am still trying to figure out why the sound gos out on these 203 chassis,
you pick the set up, take it to the shop plug it in to check it out and the
sound is ok, I've had a lot of these do the same thing, it has gotten to
where I just tell them to unplug the set and plug it back in again and 9
times out ao 10 the set is ok, so you are giving away info for nothing.
Need some idea about these.
Thanks
Vince
 
J

Jumpster Jiver

Jan 1, 1970
0
Vince said:
Hi!
I am still trying to figure out why the sound gos out on these 203 chassis,
you pick the set up, take it to the shop plug it in to check it out and the
sound is ok, I've had a lot of these do the same thing, it has gotten to
where I just tell them to unplug the set and plug it back in again and 9
times out ao 10 the set is ok, so you are giving away info for nothing.
Need some idea about these.
Thanks
Vince
Many threads about this recently. There is no real fix, but a
workarouns is a cap from a pin of the micro to somewhere else, maybe
round. Look it up.
The cap will also disable CC, so it's not a completely perfect fix.
 
A

Art

Jan 1, 1970
0
Again, Thomson mentions "They are working on it" since the early CTC19X
Series. Still no fix from them other than unplugging the set and plugging it
back in. Great Design!! As mentioned, check the other threads. Putting the
cap into the set fixes the sound dropout but disables the Closed Caption.
Not a manufacturer recommend fix!
 
L

Leonard Caillouet

Jan 1, 1970
0
If you don't have the same source, and tune to the same channels, you may
not be able to duplicate the problem. Even if you do you may not get the
same signal condition that triggers the problem.

Do some searching. There is much discussion on this matter and patches.
You might get on some of the many tech forums where techs share advice and
fixes. You can find lots of this info in the archives of this group with a
Google search. There is also an article in "The Speaker", a newsletter
published online by NESDA Ohio and can be accessed by simply signing up at
their site. There are many useful articles there.

Some places that you might look to for resources for service techs are
below. There are many more.

http://www.repairfaq.org/
http://www.nesda-ohio.com/
www.tech-assist.org
http://wa6ati.com/
http://wa6ati.com/
http://www.anatekcorp.com/
http://come.to/teklinks
 
G

Guest

Jan 1, 1970
0
Hi. For what it is worth, something I have learned about this problem, as I
have one to play with. I have found a workaround that works like a champ,
provided you have the A/V jacks on back and either a vcr, digital cable or
sat box. Take the output from your box of choice and connect to A/V jacks.
Then switch to A/V input with remote. The sound problem doesn't seem to
affect these jacks, and you get a sharper picture to boot.

I tried disconnecting the GEM module, which seemed to do the trick, but in
reality it didn't, as I had unplugged set to try the idea out.

I will see how the A/V bypass does, but no complaint so far. I know it isn't
a fix, but it was the only option available to me, see below.

I know it is some signal sent from the broadcaster, with 2 too many bits, or
some such, that overloads a buffer. I had considered doing the cap bypass
but couldn't, as the owner is 85 years old, has 2 hearing aids, and
deinitely uses closed caption.

Danny
 
T

tvguy

Jan 1, 1970
0
RCA CTC195, CTC197, CTC203 Audio-Dropout "Glitch"

THOMSON AUDIO DROP-OUT

There has been a situation when in some RCA/GE televisions
low-level,
scratchy-sounding noise comes out of the speakers instead of norma
audio, or when video is muted. These problems can occur when invali
XDS data is broadcast by television stations and received by certai
Thomson television receivers. XDS data is digital information place
within the video signal's vertical interval of an analog (NTSC
television transmission. This data is used by the microprocessor i
the television receiver. It may be transmitted from any analo
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 2
contains two captioning channels (CC1 and CC2) and tw
"text" channels (TEXT1 and TEXT2). All four of these dat
channels share that 600 cps data stream, and the information i
sorted out using packet headers. Field 2 contains a matching set o
data channels (CC3, CC4, TEXT3, and TEXT4), and can also contai
extended data services (XDS) packets.

The XDS (extended data services) provide information about the curren

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 weathe
service warning codes.

The "Thomson audio drop-out problem" occurs when
broadcaster sends invalid XDS data - that is, data that does no
contain truncation packets. There are certain XDS encoders on th
market that broadcasters may use that will do this. Thomso
television receivers using 16-bit microprocessors (i.e.
CTC197/PTK195 chassis) are programmed to decode XDS data by countin
data packets. When the microprocessor encounters corrupt data with n
truncation packets, the data overflows into memory registers where i
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/o

video).

When the unit is unplugged and replugged, it empties these register
of the corrupt data.

It is good to know that this problem was resolved in newer chassi
designs that use 32-bit microprocessors (i.e. MM101/102 an
DTV306/307).

But the vulnerable Thomson televisions will do this as they ar
receiving
invalid data from a station to which the MAIN TUNER is tuned. This i
why it is so important to find out what channel, and mor
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 i
valid (includes the necessary truncation packets), so that thei
signal is always 100% valid, and does not mess up these Thomso
receivers. Some retailers have someone assigned to contact suspecte
broadcasters. Once the customer identifies the program (o
commercial) was being watched (including the time of day) when th
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 custome
recorded from a previously-aired television program.

So the fix is to place a 1mfd capacitor to ground on U13101(15). Thi
swamps the closed caption data to the micro and stops the reception o
the defective data packet. In the event that later on the resolve th
defective data problem the capacitor can be removed. the close
caption feature will not work with this cap. installed
 

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