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mlv
 
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Default Sony KV-M1420U Television - No Colour

Our Sony 14" KV-M1420U television has suddenly lost its colour.

The picture is still perfect, but in monochrome. Sometimes the colour will
return if the television is switched to 'off' or 'standby' and then switched
back on. When the colours fails, it changes instantly from colour to black
& white, as if a switch had been operated. There is no gradual fade.

The various on-screen control icons and the channel numbers still retain
their colour (light green), even when the picture is in black & white.

As it's a Sony, I suspect dry joints. I also hope that the specific nature
of the fault will point to a particular board or component that I can repair
myself.

Can anyone give me a simple guide as to what might be the faulty unit and
where it is located?

TIA
--
Mike
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Dave Stanton
 
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Default Sony KV-M1420U Television - No Colour



As it's a Sony, I suspect dry joints. I also hope that the specific
nature of the fault will point to a particular board or component that I
can repair myself.

Can anyone give me a simple guide as to what might be the faulty unit and
where it is located?

TIA


From the way you speak, of dry joints and Sony, are you in the trade ?

Dave

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And you were born knowing all about ms windows....??

  #3   Report Post  
The Natural Philosopher
 
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Default Sony KV-M1420U Television - No Colour

Dave Stanton wrote:

As it's a Sony, I suspect dry joints. I also hope that the specific
nature of the fault will point to a particular board or component that I
can repair myself.

Can anyone give me a simple guide as to what might be the faulty unit and
where it is located?

TIA


From the way you speak, of dry joints and Sony, are you in the trade ?



Mm. ALL color lost, not just one gun eh...

Sounds like maybe whatever picks out the color subcarrier is packing up.

Is teher a crystal in there somewhere? That runs teh PAL side of things?
They occasionally give up and stop osscilatng.

I had a non sony set obnce that required a thump to get the odd color
back. I opened it up and dicoivered zillions of eyelets instead of
through plated holes. I resolderd every one.

Set worked another 5 years faultlessly, till it got struck by lightning...


Dave




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mlv
 
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Default Sony KV-M1420U Television - No Colour

Dave Stanton wrote:

From the way you speak, of dry joints and
Sony, are you in the trade ?


No, but I have yet to own a Sony television (or radio, for that matter) that
doesn't suffer from a dry joint problem once it's a few years old.

When my 21" Sony TV started playing up a while back, the technician that
repaired it said he found 47 dry joints. My previous Sony TV suffered dry
joint problems on two separate occasions.

Dry joints do seem to be synonymous with Sony.

The 14" TV isn't worth as much as a Service Centre would charge for the
repair, so if I can identify the likely fault, I'll have a go at repairing
it myself.
--
Mike
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mlv
 
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Default Sony KV-M1420U Television - No Colour

"The Natural Philosopher" wrote:

Mm. ALL color lost, not just one gun eh...


Yep, all colour lost - a perfect black & white picture.

Sounds like maybe whatever picks out the color subcarrier is packing up.

Is there a crystal in there somewhere? That runs the
PAL side of things?
They occasionally give up and stop oscillating.


Could be - I'm hoping someone will tell me.

I had a non Sony set once that required a thump to get
the odd color back. I opened it up and discovered zillions
of eyelets instead of through plated holes. I resoldered every one.


The tradition thump does not bring the colour back on my 14" Sony.
--
Mike
-Please remove 'safetycatch' before firing off your reply-




  #6   Report Post  
OldScrawn
 
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Default Sony KV-M1420U Television - No Colour

The tradition thump does not bring the colour back on my 14" Sony.

it did on mine!
  #7   Report Post  
Bob Minchin
 
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Default Sony KV-M1420U Television - No Colour


mlv wrote in message ...
Our Sony 14" KV-M1420U television has suddenly lost its colour.

The picture is still perfect, but in monochrome. Sometimes the colour will
return if the television is switched to 'off' or 'standby' and then

switched
back on. When the colours fails, it changes instantly from colour to black
& white, as if a switch had been operated. There is no gradual fade.

The various on-screen control icons and the channel numbers still retain
their colour (light green), even when the picture is in black & white.

As it's a Sony, I suspect dry joints. I also hope that the specific nature
of the fault will point to a particular board or component that I can

repair
myself.

Can anyone give me a simple guide as to what might be the faulty unit and
where it is located?

TIA
--
Mike
-Please remove 'safetycatch' before firing off your reply-




Mike,

are you sure about that model number?
I have a sony 14" manual here and all the variants are
KV-14M or T1letter according to country of use

The UK model with UHF tuner is KV-14T1U (M indicates a vhf/uhf tuner)

If your set is similar to mine then look out for a 40 pin chip MC44007P
which is the Chroma processor which has a crystal running at 4x the colour
subcarrier eg 17.734 MHz. One end of the crystal connects to pin 33.

HTH

Bob


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mlv
 
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Default Sony KV-M1420U Television - No Colour

Bob Minchin wrote:

Mike,

are you sure about that model number?
I have a Sony 14" manual here and all the variants are
KV-14M or T1letter according to country of use

The UK model with UHF tuner is KV-14T1U (M indicates a vhf/uhf tuner)

If your set is similar to mine then look out for a 40 pin chip MC44007P
which is the Chroma processor which has a crystal running at 4x the colour
subcarrier eg 17.734 MHz. One end of the crystal connects to pin 33.


Hi Bob

Yes, the model number is KV-M1420U (S/N: 6043B75). The manual listed three
model numbers, so I took the details off the TV rating plate. I've had the
TV a while, maybe 12-14 years!

This MC44007P chip, is it plug in or soldered? Are you suggesting the chip
might need replacing, or that I should check for dry joints at its pins? Or
is a faulty crystal more likely? Assuming I have the back off the TV and am
looking inside, where is the PCB carrying this chip most likely to be
located?

The fault has gone away for the past three days and the television is
working normally with good colour at the moment. I'm sure the fault will
return.

Thanks for your help.
--
Mike
-Please remove 'safetycatch' before firing off your reply-


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Bob Minchin
 
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Default Sony KV-M1420U Television - No Colour


mlv wrote in message ...
Bob Minchin wrote:

Mike,

are you sure about that model number?
I have a Sony 14" manual here and all the variants are
KV-14M or T1letter according to country of use

The UK model with UHF tuner is KV-14T1U (M indicates a vhf/uhf tuner)

If your set is similar to mine then look out for a 40 pin chip MC44007P
which is the Chroma processor which has a crystal running at 4x the

colour
subcarrier eg 17.734 MHz. One end of the crystal connects to pin 33.


Hi Bob

Yes, the model number is KV-M1420U (S/N: 6043B75). The manual listed three
model numbers, so I took the details off the TV rating plate. I've had the
TV a while, maybe 12-14 years!

This MC44007P chip, is it plug in or soldered? Are you suggesting the chip
might need replacing, or that I should check for dry joints at its pins?

Or
is a faulty crystal more likely? Assuming I have the back off the TV and

am
looking inside, where is the PCB carrying this chip most likely to be
located?

The fault has gone away for the past three days and the television is
working normally with good colour at the moment. I'm sure the fault will
return.

Thanks for your help.
--
Mike
-Please remove 'safetycatch' before firing off your reply-



Hi Mike,

It does sound like you have a model not covered by my service manual. From
memory mine Tv is about 6 years old.
I mentioned the the part number of the chroma processor simply to help you
find the crystal. Once located you could check to see if it is oscillating.
I don't know if you have the right sort of test equipment for this anyway or
indeed would recognise a crystal.

As you say it is now working I would suspect dry joints. I doubt if the ICs
are socketed but if they are, dirt or corrosion on the pins can be an issue.
If you are comfortable with using a fine soldering iron, then reheating
joints in the region of the colour crystal could do the trick.


Try http://www.maplin.co.uk/ and search for Crystal to see pictures of a
crystal - usually silvery metal cans , sometimes with plastic sleeves.

frequency will be a multiple of 4.433MHz either 1x 2x 3x or 4x


HTH

Bob


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Mathew J. Newton
 
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Default Sony KV-M1420U Television - No Colour

"mlv" wrote in message
...
Our Sony 14" KV-M1420U television has suddenly lost its colour.

snip

I've got a KV-M1421U (teletext version of yours?) with *exactly* the same
problem. I haven't got round to attempting any fix yet but I did some web
hunting and it would appear, as others have said, that dry solder joints are
common culprits for this problem.

Looking at the Usenet posting at http://tinyurl.com/2sr8b echos the
suggestions of others in this thread of resoldering the crystal. I will give
this a shot next week and let you know how I get on.

Incidentally, I can confirm that my teletext remains in full colour, as per
the description in the above URL so hopefully we could be onto winners here!

Cheers,

Mat




  #11   Report Post  
Nigel
 
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Default Sony KV-M1420U Television - No Colour

"mlv" wrote in
:

Our Sony 14" KV-M1420U television has suddenly lost its colour.

The picture is still perfect, but in monochrome. Sometimes the colour
will return if the television is switched to 'off' or 'standby' and
then switched back on. When the colours fails, it changes instantly
from colour to black & white, as if a switch had been operated. There
is no gradual fade.


This is usually caused by trimmer CT332. You can either clean and adjust
it, or replace it with a 15pF capacitor.
  #12   Report Post  
Keiron Carroll
 
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Default Sony KV-M1420U Television - No Colour

In message , Nigel
writes
"mlv" wrote in
:

Our Sony 14" KV-M1420U television has suddenly lost its colour.

The picture is still perfect, but in monochrome. Sometimes the colour
will return if the television is switched to 'off' or 'standby' and
then switched back on. When the colours fails, it changes instantly
from colour to black & white, as if a switch had been operated. There
is no gradual fade.


This is usually caused by trimmer CT332. You can either clean and adjust
it, or replace it with a 15pF capacitor.


Nigels' right here. It's a common fault. You'll see a small 'pot' next
to the crystal. Note what position it's in now. With a trimmer tool, or
very small screwdriver just give it a tweak and your colour will come
back They go int
'dead spot' . You can put it back to it's original position and your
probably going to be o.k. Ideally a new oscillator trimmer should be
fitted but you'll probably be o.k. Although the crystal osc itself can
cause this problem and is common on other makes, on these Sony's it
always seems to be this little bugger.

Hope this helps,

Keiron
--




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mlv
 
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Default Sony KV-M1420U Television - No Colour

Keiron Carroll

Nigels' right here. It's a common fault. You'll see a small 'pot' next
to the crystal. Note what position it's in now. With a trimmer tool, or
very small screwdriver just give it a tweak and your colour will come
back They go int


????

'dead spot' . You can put it back to it's original position and your
probably going to be o.k. Ideally a new oscillator trimmer should be
fitted but you'll probably be o.k. Although the crystal osc itself can
cause this problem and is common on other makes, on these Sony's it
always seems to be this little bugger.


Thanks for the information guys. Next time the colour goes (it's been fine
for the last week or so) I'll give CT332 a tweak.
--
Mike
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