LCD TV screen faulty

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G

GT

This is a post about a faulty 32" Crown TV. A little google hunting and I
think it is model CTT3207W. The TV is never actually used to watch 'tv', but
as a monitor on a PC via the s-video port and a monitor for a playstation
via a scart socket.

The TV has started to display psychodelic colours and the picture
occasionally jumps to the right for a few minutes (leaving 6" black bap on
the left).

The TV works perfectly for the first 10-15 minutes so I presume the problem
is in a part that takes about that time to warm up. It used to display
strange colours and picture shifts for about half-an-hour before returning
to normal, but now the colours appear after 10-15 minutes and stay.

Does this sound like the LCD panel itself is faulty, or the circuit board in
the TV?

Are TV circuit boards easily replaced, or are they specific and tied to the
LCD panel?

Any tips or advice before I reach for my screwdriver and ebay?

Ta,
GT
 
GT said:
This is a post about a faulty 32" Crown TV. A little google hunting and I
think it is model CTT3207W. The TV is never actually used to watch 'tv',
but as a monitor on a PC via the s-video port and a monitor for a
playstation via a scart socket.

The TV has started to display psychodelic colours and the picture
occasionally jumps to the right for a few minutes (leaving 6" black bap on
the left).

The TV works perfectly for the first 10-15 minutes so I presume the
problem is in a part that takes about that time to warm up. It used to
display strange colours and picture shifts for about half-an-hour before
returning to normal, but now the colours appear after 10-15 minutes and
stay.

Does this sound like the LCD panel itself is faulty, or the circuit board
in the TV?

Are TV circuit boards easily replaced, or are they specific and tied to
the LCD panel?

Any tips or advice before I reach for my screwdriver and ebay?
Click to expand...

Looking on ebay, there seems to be control boards and inverter boards for
that model. Anyone know if a faulty control board or inverter board could be
the cause of the problems I described?
 
GT said:
Looking on ebay, there seems to be control boards and inverter boards for
that model. Anyone know if a faulty control board or inverter board could be
the cause of the problems I described?
Click to expand...

Inverter only affects the backlight, and whether you can see a
picture or not.

LCD panel problems, cause vertical lines of bright pixels. That
happens, when a row or column is defective, that kind of thing.
There are large driver ICs, that drive the matrix, and a failure
in one of those chips, could affect a column of bright pixels. Stuck
individual pixels is another kind of fault, which is a panel related
issue.

Your LSD color scheme, sounds like a controller issue. But exactly
what, I can't begin to guess. Bad RAM on a graphics card could
do it, so at the very least, connect a regular monitor to the
computer and verify the video card is still good.

And vice-versa. Connect the 32" Crown to another computer, and
verify the Crown is still faulty.

Maybe some chip on the controller of the Crown, has RAM inside
it, and that's where the weird colors are coming from. A bad
RAM chip on the controller.

Do a few more tests to be sure.

And if it works as a TV set, the signal might not be
taking the same path through the hardware. So it could be
restricted to one of the conversion or scaling functions
on the controller board.

Paul
 
Paul said:
Inverter only affects the backlight, and whether you can see a
picture or not.
Click to expand...

So its not that then - backlight is fine. Picture is present (and correct
for 10 mins!)
LCD panel problems, cause vertical lines of bright pixels. That
happens, when a row or column is defective, that kind of thing.
There are large driver ICs, that drive the matrix, and a failure
in one of those chips, could affect a column of bright pixels. Stuck
individual pixels is another kind of fault, which is a panel related
issue.
Click to expand...

I don't think its a panel problem - there are no dead pixels or
vertical/horizontal lines - Once the TV is warmed up, this problem affects
the entire picture.
Your LSD color scheme, sounds like a controller issue. But exactly
what, I can't begin to guess. Bad RAM on a graphics card could
do it, so at the very least, connect a regular monitor to the
computer and verify the video card is still good.

And vice-versa. Connect the 32" Crown to another computer, and
verify the Crown is still faulty.
Click to expand...

It does actually look like a faulty graphics card memory type problem - I've
had that problem on a desktop build project recently, but the PC is fine and
healthy. I have tested the TV with 3 different inputs - playstation via
scart socket, pc via s-video (tried 2 pcs) and freeview via scart. Problem
is exactly the same with all inputs.
Maybe some chip on the controller of the Crown, has RAM inside
it, and that's where the weird colors are coming from. A bad
RAM chip on the controller.
Click to expand...

I found 2 used controller cards on ebay for £20-£40, so I'm tempted to
replace that. I'm going to wait a few days and see if anyone else has
anything to suggest. Thanks for your reply Paul.
 
GT said:
So its not that then - backlight is fine. Picture is present (and correct
for 10 mins!)


I don't think its a panel problem - there are no dead pixels or
vertical/horizontal lines - Once the TV is warmed up, this problem affects
the entire picture.


It does actually look like a faulty graphics card memory type problem - I've
had that problem on a desktop build project recently, but the PC is fine and
healthy. I have tested the TV with 3 different inputs - playstation via
scart socket, pc via s-video (tried 2 pcs) and freeview via scart. Problem
is exactly the same with all inputs.


I found 2 used controller cards on ebay for £20-£40, so I'm tempted to
replace that. I'm going to wait a few days and see if anyone else has
anything to suggest. Thanks for your reply Paul.
Click to expand...

Do you have a link to a picture of the controller board ?

Paul
 
Paul said:
Do you have a link to a picture of the controller board ?
Click to expand...

I don't have an online photo account, but I've taken the TV apart and the
main control board is a 17MB08P-5, as found in ebay UK item number
200530745678. There is an online manual easily found by searching on that
model part number.

The board I've taken out looks visually perfect - all capacitors are
perfect, no leaks. no corrosion or brown areas.

On the rear of the board, there is an aftermarket addition (looks like) of a
short piece of wire connecting C820 up to R801. Don't know what that is for.
 
Somewhere said:
I don't have an online photo account, but I've taken the TV apart and
the main control board is a 17MB08P-5, as found in ebay UK item number
200530745678.
Click to expand...

LOL, you couldn't have just cut'n'pasted a URL? There are those of us who's
cookies / ebay's server try to default to local ebay when an ebay address is
typed in.
There is an online manual easily found by searching on
that model part number.

The board I've taken out looks visually perfect - all capacitors are
perfect, no leaks. no corrosion or brown areas.
Click to expand...

Visually perfect (aluminium electolytic) capacitors can still be out-of-spec
enough to cause major problems and often are.

Depending on the number of ali cans and your ability to source them at a
reasonable price it could be an option to try replacing them before shelling
out on a 'new' controller board.
On the rear of the board, there is an aftermarket addition (looks
like) of a short piece of wire connecting C820 up to R801. Don't know
what that is for.
Click to expand...

Often PCB design software will give you a couple of options; A larger and/or
more complex board where no wire jumpers are needed or a much simpler /
cheaper board that might need a wire jumper or two to take the place of PCB
traces that are problematic.

Also, sometimes later releases of electronics have such small 'mods' done as
a trace as designed might be found (over time used) to be unable to carry
sufficient current and cause problems. A wire jumper can fix that problem.

Good luck.
--
Shaun.

"He who fights with monsters might take care lest he thereby become a
monster. And if you gaze for long into an abyss, the abyss gazes also
into you." Friedrich Wilhelm Nietzsche
 
GT said:
I don't have an online photo account, but I've taken the TV apart and the
main control board is a 17MB08P-5, as found in ebay UK item number
200530745678. There is an online manual easily found by searching on that
model part number.

The board I've taken out looks visually perfect - all capacitors are
perfect, no leaks. no corrosion or brown areas.

On the rear of the board, there is an aftermarket addition (looks like) of a
short piece of wire connecting C820 up to R801. Don't know what that is for.
Click to expand...

I found a schematic, but it's for what might have been a previous
model of the controller board.

http://elektrotanya.com/vestel_17mb08-3_d_3972_sch.pdf/download.html

The square chip in the center of that controller, could be a Genesis GM6015.

http://www.digchip.com/datasheets/parts/datasheet/177/GM6015.php

And that turns out to be a "video processor" chip. It accepts a couple
digital streams from video decoder chips (they would convert composite or
S-video into a digital stream 4:2:2), has some connection to OSD,
and there is an 8MB SDRAM chip connected to it. (That could be for
frame buffering, or used for re-sampling to a different resolution.)

In this picture, the thing with the green label on it is the
video processor, and the chip just below it is the SDRAM. If something
were to "go south", that would be where I might start looking. That's
the most likely area for generating psychedelic colors. (Where the
colors go, only in the OSD area, within one of the Picture-in-Picture
windows etc., might give you more hints as to what is busted.)

http://www.chsinteractive.co.uk/images/products/1190171821-67163200.jpg

That type of SDRAM chip, is the kind of thing you might see in a
modem/router or plain router box. It's 32 bits wide, which is not
popular for building DIMMs for computers. So in terms of replacing
a chip like that, it might be a bit more difficult to find. The 8MB
capacity, is 2M x 32. (I think I have a chip like that, sitting
three feet from me, but it's a different brand :-) )

I haven't looked much further than that so far. I was surprised I could
find any schematic on the web, that wasn't a "pay as you go". That schematic
probably isn't the circuit for your controller, but it might be close
enough conceptually, to give you some guidance.

The chip with the pink label in the picture, could be an EEPROM for the
chip next to it. The SDA5550M is an 8051 processor core, and might be
the part that does the OSD (on-screen display). That probably isn't
messing up the colors. The output of the SDA5550M is sent over to
the square chip, to be mixed in with the other video sources.

This is a brochure for the SDA5550M. The SDA5550M is ROM-less
internally, and is 100 pins in size. It connects to an external ROM,
which I assume is that ugly big DIP package with the pink label
next to it. That's where the program to draw the OSD is stored.

http://www.datasheetcatalog.org/datasheet/infineon/1-sda555x.pdf

You could spend the whole day, picking that thing apart :-)

Have fun,
Paul
 
Paul said:
I found a schematic, but it's for what might have been a previous
model of the controller board.

http://elektrotanya.com/vestel_17mb08-3_d_3972_sch.pdf/download.html

The square chip in the center of that controller, could be a Genesis
GM6015.

http://www.digchip.com/datasheets/parts/datasheet/177/GM6015.php

And that turns out to be a "video processor" chip. It accepts a couple
digital streams from video decoder chips (they would convert composite or
S-video into a digital stream 4:2:2), has some connection to OSD,
and there is an 8MB SDRAM chip connected to it. (That could be for
frame buffering, or used for re-sampling to a different resolution.)

In this picture, the thing with the green label on it is the
video processor, and the chip just below it is the SDRAM. If something
were to "go south", that would be where I might start looking. That's
the most likely area for generating psychedelic colors. (Where the
colors go, only in the OSD area, within one of the Picture-in-Picture
windows etc., might give you more hints as to what is busted.)

http://www.chsinteractive.co.uk/images/products/1190171821-67163200.jpg

That type of SDRAM chip, is the kind of thing you might see in a
modem/router or plain router box. It's 32 bits wide, which is not
popular for building DIMMs for computers. So in terms of replacing
a chip like that, it might be a bit more difficult to find. The 8MB
capacity, is 2M x 32. (I think I have a chip like that, sitting
three feet from me, but it's a different brand :-) )

I haven't looked much further than that so far. I was surprised I could
find any schematic on the web, that wasn't a "pay as you go". That
schematic
probably isn't the circuit for your controller, but it might be close
enough conceptually, to give you some guidance.

The chip with the pink label in the picture, could be an EEPROM for the
chip next to it. The SDA5550M is an 8051 processor core, and might be
the part that does the OSD (on-screen display). That probably isn't
messing up the colors. The output of the SDA5550M is sent over to
the square chip, to be mixed in with the other video sources.

This is a brochure for the SDA5550M. The SDA5550M is ROM-less
internally, and is 100 pins in size. It connects to an external ROM,
which I assume is that ugly big DIP package with the pink label
next to it. That's where the program to draw the OSD is stored.

http://www.datasheetcatalog.org/datasheet/infineon/1-sda555x.pdf

You could spend the whole day, picking that thing apart :-)

Have fun,
Paul
Click to expand...

For £25, I have just bought a replacement board from ebay! Will report back
in a few days when it has arrived...
 
Paul said:
I found a schematic, but it's for what might have been a previous
model of the controller board.

http://elektrotanya.com/vestel_17mb08-3_d_3972_sch.pdf/download.html

The square chip in the center of that controller, could be a Genesis
GM6015.

http://www.digchip.com/datasheets/parts/datasheet/177/GM6015.php

And that turns out to be a "video processor" chip. It accepts a couple
digital streams from video decoder chips (they would convert composite or
S-video into a digital stream 4:2:2), has some connection to OSD,
and there is an 8MB SDRAM chip connected to it. (That could be for
frame buffering, or used for re-sampling to a different resolution.)

In this picture, the thing with the green label on it is the
video processor, and the chip just below it is the SDRAM. If something
were to "go south", that would be where I might start looking. That's
the most likely area for generating psychedelic colors. (Where the
colors go, only in the OSD area, within one of the Picture-in-Picture
windows etc., might give you more hints as to what is busted.)

http://www.chsinteractive.co.uk/images/products/1190171821-67163200.jpg

That type of SDRAM chip, is the kind of thing you might see in a
modem/router or plain router box. It's 32 bits wide, which is not
popular for building DIMMs for computers. So in terms of replacing
a chip like that, it might be a bit more difficult to find. The 8MB
capacity, is 2M x 32. (I think I have a chip like that, sitting
three feet from me, but it's a different brand :-) )

I haven't looked much further than that so far. I was surprised I could
find any schematic on the web, that wasn't a "pay as you go". That
schematic
probably isn't the circuit for your controller, but it might be close
enough conceptually, to give you some guidance.

The chip with the pink label in the picture, could be an EEPROM for the
chip next to it. The SDA5550M is an 8051 processor core, and might be
the part that does the OSD (on-screen display). That probably isn't
messing up the colors. The output of the SDA5550M is sent over to
the square chip, to be mixed in with the other video sources.

This is a brochure for the SDA5550M. The SDA5550M is ROM-less
internally, and is 100 pins in size. It connects to an external ROM,
which I assume is that ugly big DIP package with the pink label
next to it. That's where the program to draw the OSD is stored.

http://www.datasheetcatalog.org/datasheet/infineon/1-sda555x.pdf

You could spend the whole day, picking that thing apart :-)

Have fun,
Paul
Click to expand...

New board arrived. Installed. All OK again - screen is perfect! Thanks for
the help.
 
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