Muffled TV audio - Philips TDA9380 IC

[jamie powell]

Hi,
I have a Roadstar 10" CRT TV, PAL/SECAM model CTV1030.
The TV has muffled sound when watching broadcast TV signals (analogue) using
its antenna input, but when an AV source is connected to its SCART input,
the sound is fine.

The set's main IC chip is a Philips TDA9380PS/N2/3I. I'm not an electronics
expert, but I found a datasheet for this range of chips online
( http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/9/TDA938X.shtml )
which, afaict, says that FM audio demodulation and de-emphasis takes place
within the chip itself.

I connected the chip's audio output pin directly to an external
amplifier-speaker, and the muffled effect was still present, possibly
suggesting that something within the chip itself is causing the issue, and
not some form of external low-pass audio filtering on the chassis.

Could anyone with experience with this IC chip suggest what the cause of the
problem might be?

Thanks,
Jamie.

 

[Meat Plow]

On Wed, 15 Jul 2009 20:10:24 +0100, "jamie powell"
<jamie_p84@excite.com>wrote:

Hi,
I have a Roadstar 10" CRT TV, PAL/SECAM model CTV1030.
The TV has muffled sound when watching broadcast TV signals (analogue) using
its antenna input, but when an AV source is connected to its SCART input,
the sound is fine.

The set's main IC chip is a Philips TDA9380PS/N2/3I. I'm not an electronics
expert, but I found a datasheet for this range of chips online
( http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/9/TDA938X.shtml )
which, afaict, says that FM audio demodulation and de-emphasis takes place
within the chip itself.

I connected the chip's audio output pin directly to an external
amplifier-speaker, and the muffled effect was still present, possibly
suggesting that something within the chip itself is causing the issue, and
not some form of external low-pass audio filtering on the chassis.

Could anyone with experience with this IC chip suggest what the cause of the
problem might be?

Unless the chip needs an external component or two for sound
processing then you've found the problem.

 

[jamie powell]

"Meat Plow" <meat@petitmorte.net> wrote in message
news:2vi4li.f1d.19.1@news.alt.net...

On Wed, 15 Jul 2009 20:10:24 +0100, "jamie powell"

Unless the chip needs an external component or two for sound
processing then you've found the problem.

You think it's a faulty chip?
I know of another person with the same model TV who has the same issue, so I
figured it was either some kind of chip configuration problem, or a design
fault on the TV's PCB.

It could be a design flaw with the chip, but given that it's made by
Philips, and was apparently used in a lot of "economy" model TVs of various
brands, I'd be surprised if such a major flaw had gotten past
testing/quality control and into mass production unnoticed.

 

[Meat Plow]

On Thu, 16 Jul 2009 00:26:36 +0100, "jamie powell"
<jamie_p84@excite.com>wrote:

"Meat Plow" <meat@petitmorte.net> wrote in message
news:2vi4li.f1d.19.1@news.alt.net...
On Wed, 15 Jul 2009 20:10:24 +0100, "jamie powell"

Unless the chip needs an external component or two for sound
processing then you've found the problem.

You think it's a faulty chip?
I know of another person with the same model TV who has the same issue, so I
figured it was either some kind of chip configuration problem, or a design
fault on the TV's PCB.

It could be a design flaw with the chip, but given that it's made by
Philips, and was apparently used in a lot of "economy" model TVs of various
brands, I'd be surprised if such a major flaw had gotten past
testing/quality control and into mass production unnoticed.

You didn't mention the other person with the same model/same problem.

If you're not happy with it sell it and purchase something else.

 

[Dave Plowman (News)]

In article <h3loja$eod$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

You think it's a faulty chip? I know of another person with the same
model TV who has the same issue, so I figured it was either some kind
of chip configuration problem, or a design fault on the TV's PCB.

It could be a design flaw with the chip, but given that it's made by
Philips, and was apparently used in a lot of "economy" model TVs of
various brands, I'd be surprised if such a major flaw had gotten past
testing/quality control and into mass production unnoticed.

Could be designed like that for a nice 'mellow' sound. And reducing
intercarrier etc buzz from a cheap design.

--
*I get enough exercise just pushing my luck.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[jamie powell]

"Meat Plow" <meat@petitmorte.net> wrote in message
news:2vjvcf.3j6.19.1@news.alt.net...

On Thu, 16 Jul 2009 00:26:36 +0100, "jamie powell"

You didn't mention the other person with the same model/same problem.

If you're not happy with it sell it and purchase something else.

With all due respect, this is an electronics repair group.
If you can't offer relevant and helpful advice to people with queries on
electronics repair, then don't post.

 

[jamie powell]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507bc9e462dave@davenoise.co.uk...

Could be designed like that for a nice 'mellow' sound. And reducing
intercarrier etc buzz from a cheap design.

Most unlikely, and it doesn't make anything sound "mellow" - one can barely
hear what people are saying. And low-pass audio filtering wouldn't reduce
intercarrier buzz in any event.

 

[Meat Plow]

On Thu, 16 Jul 2009 20:02:57 +0100, "jamie powell"
<jamie_p84@excite.com>wrote:

"Meat Plow" <meat@petitmorte.net> wrote in message
news:2vjvcf.3j6.19.1@news.alt.net...
On Thu, 16 Jul 2009 00:26:36 +0100, "jamie powell"

You didn't mention the other person with the same model/same problem.

If you're not happy with it sell it and purchase something else.

With all due respect, this is an electronics repair group.
If you can't offer relevant and helpful advice to people with queries on
electronics repair, then don't post.

With all do respect, go fuck yourself.

 

[Dave Plowman (News)]

In article <h3ntsg$nl5$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507bc9e462dave@davenoise.co.uk...

Could be designed like that for a nice 'mellow' sound. And reducing
intercarrier etc buzz from a cheap design.

Most unlikely, and it doesn't make anything sound "mellow" - one can
barely hear what people are saying.

Turn it up then.

And low-pass audio filtering
wouldn't reduce intercarrier buzz in any event.

Bollocks.

--
*I have a degree in liberal arts -- do you want fries with that

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[jamie powell]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507bf876b6dave@davenoise.co.uk...

In article <h3ntsg$nl5$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507bc9e462dave@davenoise.co.uk...

Could be designed like that for a nice 'mellow' sound. And reducing
intercarrier etc buzz from a cheap design.

Most unlikely, and it doesn't make anything sound "mellow" - one can
barely hear what people are saying.

Turn it up then.

Doesn't help - makes it worse actually.

And low-pass audio filtering
wouldn't reduce intercarrier buzz in any event.

Bollocks.

Duh... buzz is low frequency innit. idiot.

 

[none]

jamie powell wrote:

Hi,
I have a Roadstar 10" CRT TV, PAL/SECAM model CTV1030.
The TV has muffled sound when watching broadcast TV signals (analogue) using
its antenna input, but when an AV source is connected to its SCART input,
the sound is fine.

The set's main IC chip is a Philips TDA9380PS/N2/3I. I'm not an electronics
expert, but I found a datasheet for this range of chips online
( http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/9/TDA938X.shtml )
which, afaict, says that FM audio demodulation and de-emphasis takes place
within the chip itself.

I connected the chip's audio output pin directly to an external
amplifier-speaker, and the muffled effect was still present, possibly
suggesting that something within the chip itself is causing the issue, and
not some form of external low-pass audio filtering on the chassis.

Could anyone with experience with this IC chip suggest what the cause of the
problem might be?

Thanks,
Jamie.


Unless you have an oscilloscope, a handful of electrolytic capacitors, a

soldering iron, and spare time, you might as well give it up as a bad job.
The audio part of that IC may possibly have one or more electrolytic
caps associated with it, which may or may not have failed. It's what I'd
try first, anyway, before declaring the TV "Dumpster-chow".

 

[Dave Plowman (News)]

In article <h3obia$6r6$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

Most unlikely, and it doesn't make anything sound "mellow" - one can
barely hear what people are saying.

Turn it up then.

Doesn't help - makes it worse actually.

What would you estimate the usable frequency response as heard at the
speaker at?

And low-pass audio filtering
wouldn't reduce intercarrier buzz in any event.

Bollocks.

Duh... buzz is low frequency innit. idiot.

No - that's hum. Buzz is wideband. Have you never heard intercarrier buzz?

--
*When you've seen one shopping centre you've seen a mall*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[jamie powell]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507c2cb691dave@davenoise.co.uk...

In article <h3obia$6r6$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:
Most unlikely, and it doesn't make anything sound "mellow" - one can
barely hear what people are saying.

Turn it up then.

Doesn't help - makes it worse actually.

What would you estimate the usable frequency response as heard at the
speaker at?

I tested the line output on a spectrum analyser. It rolls of after about
7khz, but the higher frequency content is still there, just much quiter than
it should be.

And low-pass audio filtering
wouldn't reduce intercarrier buzz in any event.

Bollocks.

Duh... buzz is low frequency innit. idiot.

No - that's hum. Buzz is wideband. Have you never heard intercarrier buzz?

Of course I have. The vast majority of it is below 7khz, and there isn't any
on this set anyway.
You obviously don't know how to answer my question so kindly stfu.

I mourn the day when usenet was abandoned by academics and taken over by
conceited amateurs.

 

[Dave Plowman (News)]

In article <h3pm3n$deg$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507c2cb691dave@davenoise.co.uk...
In article <h3obia$6r6$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:
Most unlikely, and it doesn't make anything sound "mellow" - one
can barely hear what people are saying.

Turn it up then.

Doesn't help - makes it worse actually.

What would you estimate the usable frequency response as heard at the
speaker at?

I tested the line output on a spectrum analyser. It rolls of after about
7khz, but the higher frequency content is still there, just much quiter
than it should be.

You don't need anything like 7kHz for clear speech. If you did, telephones
would be no use. AM radio in the UK is 4.5 kHz band limited.

And low-pass audio filtering
wouldn't reduce intercarrier buzz in any event.

Bollocks.

Duh... buzz is low frequency innit. idiot.

No - that's hum. Buzz is wideband. Have you never heard intercarrier
buzz?

Of course I have. The vast majority of it is below 7khz, and there isn't
any on this set anyway. You obviously don't know how to answer my
question so kindly stfu.

I mourn the day when usenet was abandoned by academics and taken over by
conceited amateurs.

Why are you posting then? A pro would have no problem in sorting out the
cause, you conceited little shit.

--
*Snowmen fall from Heaven unassembled*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[jamie powell]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507c451d3adave@davenoise.co.uk...

You don't need anything like 7kHz for clear speech. If you did, telephones
would be no use. AM radio in the UK is 4.5 kHz band limited.

Both of those have a lower bass response to match. This set has a very
uneven sound by comparison.

I mourn the day when usenet was abandoned by academics and taken over by
conceited amateurs.

Why are you posting then? A pro would have no problem in sorting out the
cause, you conceited little shit.

I'm posting to ask for advice.
I'm not pretending to be competent in this area and wasting other people's
time as a result, unlike some people.

 

[Dave Plowman (News)]

In article <h3q8lo$3ib$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

You don't need anything like 7kHz for clear speech. If you did,
telephones would be no use. AM radio in the UK is 4.5 kHz band limited.

Both of those have a lower bass response to match. This set has a very
uneven sound by comparison.

Telephone spec is 300 - 3000 Hz.

But make up your mind. You were complaining about 'muffled' sound. Do you
understand the common meaning of this, sound wise?

I mourn the day when usenet was abandoned by academics and taken over
by conceited amateurs.

Why are you posting then? A pro would have no problem in sorting out
the cause, you conceited little shit.

I'm posting to ask for advice. I'm not pretending to be competent in
this area and wasting other people's time as a result, unlike some
people.

Then you could keep your posts to the point.

--
*Nostalgia isn't what is used to be.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[jamie powell]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507c5c91eddave@davenoise.co.uk...

In article <h3q8lo$3ib$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:
You don't need anything like 7kHz for clear speech. If you did,
telephones would be no use. AM radio in the UK is 4.5 kHz band limited.

Both of those have a lower bass response to match. This set has a very
uneven sound by comparison.

Telephone spec is 300 - 3000 Hz.

But make up your mind. You were complaining about 'muffled' sound. Do you
understand the common meaning of this, sound wise?

I mourn the day when usenet was abandoned by academics and taken over
by conceited amateurs.

Why are you posting then? A pro would have no problem in sorting out
the cause, you conceited little shit.

I'm posting to ask for advice. I'm not pretending to be competent in
this area and wasting other people's time as a result, unlike some
people.

Then you could keep your posts to the point.

You can't help with my question and are completely without clue, although
loathe to admit it.
All you've done is waste my time and, less importantly, yours.

 

[Dave Plowman (News)]

In article <h3qaiv$5ob$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:

Then you could keep your posts to the point.

You can't help with my question and are completely without clue,
although loathe to admit it. All you've done is waste my time and, less
importantly, yours.

How to guarantee you won't get help.

--
*No husband has ever been shot while doing the dishes *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Michael A. Terrell]

jamie powell wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507c5c91eddave@davenoise.co.uk...
In article <h3q8lo$3ib$1@aioe.org>,
jamie powell <jamie_p84@excite.com> wrote:
You don't need anything like 7kHz for clear speech. If you did,
telephones would be no use. AM radio in the UK is 4.5 kHz band limited.

Both of those have a lower bass response to match. This set has a very
uneven sound by comparison.

Telephone spec is 300 - 3000 Hz.

But make up your mind. You were complaining about 'muffled' sound. Do you
understand the common meaning of this, sound wise?

I mourn the day when usenet was abandoned by academics and taken over
by conceited amateurs.

Why are you posting then? A pro would have no problem in sorting out
the cause, you conceited little shit.

I'm posting to ask for advice. I'm not pretending to be competent in
this area and wasting other people's time as a result, unlike some
people.

Then you could keep your posts to the point.

You can't help with my question and are completely without clue, although
loathe to admit it.
All you've done is waste my time and, less importantly, yours.

Have you tried another speaker? Don't bother to reply.


--
You can't have a sense of humor, if you have no sense!

 

[Meat Plow]

On Fri, 17 Jul 2009 17:25:22 +0100, "jamie powell"
<jamie_p84@excite.com>wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:507c451d3adave@davenoise.co.uk...

You don't need anything like 7kHz for clear speech. If you did, telephones
would be no use. AM radio in the UK is 4.5 kHz band limited.

Both of those have a lower bass response to match. This set has a very
uneven sound by comparison.


I mourn the day when usenet was abandoned by academics and taken over by
conceited amateurs.

Why are you posting then? A pro would have no problem in sorting out the
cause, you conceited little shit.

I'm posting to ask for advice.

I gave you advice. Then you in a very condescending tenor insult my
intelligence by advising me this was a /repair/ newsgroup.

I'm not pretending to be competent in this area and wasting other people's
time as a result, unlike some people.

Let's see you just posted this turd;

I mourn the day when usenet was abandoned by academics and taken over by
conceited amateurs.

Seems you absolutely are pretending to be competent in this area by
judging others as /amateurs/.

Tell you what, I more than likely, was doing warranty repairs for
major manufactures while you were still in diapers so if you intended
to group me in with the conceited amateurs then you have a lot not
only to learn about electronics but also who knows what.

If you are looking for someone to guide you step by step on what to
check and possibly replace, at the very least provide a schematic of
the set.