Mitsubishi TV Salt and Pepper on screen

[amdx]

I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

Mikek

 

[John-Del]

On Tuesday, March 10, 2015 at 3:08:27 PM UTC-4, amdx wrote:

I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

Mikek

Simple: bad dmd imager. Texas Instruments had a bad run that affected an entire run from Mitsu, Toshiba, and Samsung sometime around 2007 IIRC. Samsung is telling people tough shit, not sure about Toshiba, but Mitsu (with enough crying), will ship the dmd chip to a servicer who will install it and clean the optics, you pay the labor. This info was accurate as far as March 1st this year.

Other than the TI chip, this model Mitsu is trouble free other than needing a new lamp every 6K hours or so.

 

[amdx]

On 3/10/2015 2:42 PM, John-Del wrote:

On Tuesday, March 10, 2015 at 3:08:27 PM UTC-4, amdx wrote:
I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

Mikek

Simple: bad dmd imager. Texas Instruments had a bad run that affected an entire run from Mitsu, Toshiba, and Samsung sometime around 2007 IIRC. Samsung is telling people tough shit, not sure about Toshiba, but Mitsu (with enough crying), will ship the dmd chip to a servicer who will install it and clean the optics, you pay the labor. This info was accurate as far as March 1st this year.

Other than the TI chip, this model Mitsu is trouble free other than needing a new lamp every 6K hours or so.

Very good, I had an auto seat recovered at an upholstery shop, It was
the TV in their office. I ask about it, he said when he bought it
($100), it only had maybe ten spots scattered around the screen,
and it just kept getting worse.
It's been 20 years since I was involved in the repair business,
I basically missed the flat screen change over. So I had to google
dmd imager.
http://en.wikipedia.org/wiki/Digital_micromirror_device
I printed your info and the wiki info and gave it to the upholstery
shop owner.
Nice guy, I dropped my seat cover off at about noon, he had it done
at 4:00 and I had it back on the seat and the seat back in the van by
5:00. If I had known it was that easy, I wouldn't have been driving
the van with a big hole in the drivers seat for three years.
Thanks, Mikek

 

[John-Del]

DLPs are probably the worst TVs to use in a commercial application as they usually run all day. OEM lamps are good for 6000 hours on average, web sourced knock offs about 1000 hours.

Once the DMD starts to die, the rash expands fairly rapidly. I changed one last month where the entire picture was covered with sparkles. Between the cost of the DMD image chip and the lamp usage, I would not recommend a repair on this TV that runs this many hours.

I have several customers with "institutional" use TVs (doctors, mechanics etc.) and I've located CRT TVs for them to use in their waiting areas. A good CRT TV will run almost indefinitely and care little how many hours they run. A gave a friend of mine (muffler shop) an old 80s RCA CTC130 25" for his waiting room and it's been running every day for almost 15 years straight. Kids have thrown toys at the picture tube face, scratched the tube and damaged the front control buttons, but it works by remote so no big deal. I saw it last month and the CRT is starting to show some beam scatter in the corners, so the tube is finally getting soft, but it's certainly usable.



On Tuesday, March 10, 2015 at 11:06:49 PM UTC-4, amdx wrote:

On 3/10/2015 2:42 PM, John-Del wrote:
On Tuesday, March 10, 2015 at 3:08:27 PM UTC-4, amdx wrote:
I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

Mikek

Simple: bad dmd imager. Texas Instruments had a bad run that affected an entire run from Mitsu, Toshiba, and Samsung sometime around 2007 IIRC. Samsung is telling people tough shit, not sure about Toshiba, but Mitsu (with enough crying), will ship the dmd chip to a servicer who will install it and clean the optics, you pay the labor. This info was accurate as far as March 1st this year.

Other than the TI chip, this model Mitsu is trouble free other than needing a new lamp every 6K hours or so.


Very good, I had an auto seat recovered at an upholstery shop, It was
the TV in their office. I ask about it, he said when he bought it
($100), it only had maybe ten spots scattered around the screen,
and it just kept getting worse.
It's been 20 years since I was involved in the repair business,
I basically missed the flat screen change over. So I had to google
dmd imager.
http://en.wikipedia.org/wiki/Digital_micromirror_device
I printed your info and the wiki info and gave it to the upholstery
shop owner.
Nice guy, I dropped my seat cover off at about noon, he had it done
at 4:00 and I had it back on the seat and the seat back in the van by
5:00. If I had known it was that easy, I wouldn't have been driving
the van with a big hole in the drivers seat for three years.
Thanks, Mikek

 

On Tuesday, March 10, 2015 at 3:08:27 PM UTC-4, amdx wrote:

I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

When you say "salt and pepper", do you mean white noise that a screen shows when it has no specific signal? Like this?

https://www.youtube.com/watch?v=El8mLrBSPlA

 

[amdx]

On 3/11/2015 3:18 PM, mogulah@hotmail.com wrote:

On Tuesday, March 10, 2015 at 3:08:27 PM UTC-4, amdx wrote:
I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

When you say "salt and pepper", do you mean white noise that a screen shows when it has no specific signal? Like this?

https://www.youtube.com/watch?v=El8mLrBSPlA

Nope.

"The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that."

Mikek

 

[Matthew Fries]

On Wed, 11 Mar 2015 20:48:52 -0500, amdx <nojunk@knology.net> wrote:

On 3/11/2015 3:18 PM, mogulah@hotmail.com wrote:
On Tuesday, March 10, 2015 at 3:08:27 PM UTC-4, amdx wrote:
I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

When you say "salt and pepper", do you mean white noise that a screen shows when it has no specific signal? Like this?

https://www.youtube.com/watch?v=El8mLrBSPlA


Nope.

"The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that."

Mikek

The "salt and pepper" that you are describing is a random smattering
of stuck pixels on your DLP chip. Some of them are stuck on (white)
and some are stuck off (black). I had this exact same failure on my
Samsung DLP television. It started with just a few stuck pixels, but
over time grew to much more.

My samsung DLP has an LED backlight, so I deemed it worthy to replace
the DLP chip. I bought it from shopjimmy via Amazon. The price was
about $200. It was pretty easy to replace - There are a lot of
instructions available on the web for various models. After replacing
the chip, the image on screen is just a teeny bit crooked, but I can
live with it. It was too much trouble to try to open the set and
manually re-adjust the alignment. There doesn't seem to be ANY kind of
electronic adjustment to correct this.

 

[DaveC]

"The entire screen had randomly scattered but stationary black and white
dots. Maybe about the size of the comma on your keyboard or just a little
larger. On one scene with a grey screen, and the Black and white spots, it
looked like one of the garage floors painted grey with the specks thrown on
it. Almost exactly like that."

Mikek

Like this? ::

https://www.youtube.com/watch?v=bGg_P1PqCYo

ShopJimmy has DLPs available for most back-projection TVs.

Good luck.

 

[DaveC]

I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

Mikek

FYI, the white dots are pixel mirrors that are stuck "on" (reflecting light
to the screen) and the black ones are stuck "off" (not reflecting light to
the screen).

 

[N_Cook]

On 14/03/2015 03:37, DaveC wrote:

I saw a Large Mitsubishi TV, not quite flat panel just a little
round out on rear at bottom center. I think an age clue.
The entire screen had randomly scattered but stationary black and
white dots. Maybe about the size of the comma on your keyboard or just a
little larger. On one scene with a grey screen, and the Black and white
spots, it looked like one of the garage floors painted grey with the
specks thrown on it. Almost exactly like that.

Any idea what could could this strange defect?

Mikek

FYI, the white dots are pixel mirrors that are stuck "on" (reflecting light
to the screen) and the black ones are stuck "off" (not reflecting light to
the screen).

So is it something physical making the mirrors stick or failed electronics?
With the 10 or so DLP projectors I've played with , all dumpster-fodder,
always ps failure or absent, presumably failed lamps, not a single stuck
pixel have I seen.

 

[John-Del]

On Saturday, March 14, 2015 at 1:35:09 PM UTC-4, N_Cook wrote:

So is it something physical making the mirrors stick or failed electronics?
With the 10 or so DLP projectors I've played with , all dumpster-fodder,
always ps failure or absent, presumably failed lamps, not a single stuck
pixel have I seen.

The stuck pixel phenomenon only affected a specific run from TI, somewhere in the 2007 range IIRC. I have an 06 Mitsubishi 1080P native resolution projector and this earlier model never has this problem. Later Mitsus don't either.

As for the failure mode, I'm going to presume it's mechanical. I replaced one a few weeks ago and it was loaded with bad pixels that the DMD chip had a sandblasted appearance instead of what normally looks like a perfectly reflective 16X9 mirror. I've got some scrapped going back two years and the stuck pixels are still visible by eye under magnification.

I've played around with these using heat and mechanical vibration and there has never been any effect on them. They have a torsion hinge in them and I'm guessing that they might be some sort of flexible elastomer that's failing with heat and repeated cycles.

 

[Jon Elson]

John-Del wrote:

On Saturday, March 14, 2015 at 1:35:09 PM UTC-4, N_Cook wrote:

So is it something physical making the mirrors stick or failed
electronics? With the 10 or so DLP projectors I've played with , all
dumpster-fodder, always ps failure or absent, presumably failed lamps,
not a single stuck pixel have I seen.

The stuck pixel phenomenon only affected a specific run from TI, somewhere
in the 2007 range IIRC. I have an 06 Mitsubishi 1080P native resolution
projector and this earlier model never has this problem. Later Mitsus
don't either.

As for the failure mode, I'm going to presume it's mechanical. I replaced
one a few weeks ago and it was loaded with bad pixels that the DMD chip
had a sandblasted appearance instead of what normally looks like a
perfectly reflective 16X9 mirror. I've got some scrapped going back two
years and the stuck pixels are still visible by eye under magnification.

I've played around with these using heat and mechanical vibration and
there has never been any effect on them. They have a torsion hinge in
them and I'm guessing that they might be some sort of flexible elastomer
that's failing with heat and repeated cycles.

The torsion hinge is pure aluminum, and probably thinner than the mirrors.
they build this all on a metal layer up above the chip circuitry, and
then etch out the platform under the mirrors, freeing them. They rock
back and forth under electrostatic force from pads on the chip surface
under the corners of the mirror.

The whole general scheme is in some docs published by TI a long time ago.
VERY fascinating stuff to read, some of the earliest MEMS work.
They apparently have some kind of lube layer that is supposed to keep
the mirrors from sticking, and it breaks down under UV bombardment.

The mirrors are typically 11 um across, so you would have to hit the thing
with a bullet to produce much acceleration to the mirrors. No way can
you shock the mirrors free once they have stuck.

Jon

 

[John-Del]

On Saturday, March 14, 2015 at 10:15:02 PM UTC-4, Jon Elson wrote:

The torsion hinge is pure aluminum, and probably thinner than the mirrors.
they build this all on a metal layer up above the chip circuitry, and
then etch out the platform under the mirrors, freeing them.
Jon

Thanks Jon. Makes more sense when you think about it. At the dimensions that we are talking about, etching out makes more sense than attempting to assemble with a dissimilar material for the torsion hinge. It's amazing these things actually work.

 

[amdx]

On 3/15/2015 7:11 AM, John-Del wrote:

On Saturday, March 14, 2015 at 10:15:02 PM UTC-4, Jon Elson wrote:


The torsion hinge is pure aluminum, and probably thinner than the mirrors.
they build this all on a metal layer up above the chip circuitry, and
then etch out the platform under the mirrors, freeing them.
Jon

Thanks Jon. Makes more sense when you think about it. At the dimensions that we are talking about,

etching out makes more sense than attempting to assemble with a
dissimilar material for the torsion hinge. It's amazing these things
actually work.
>

Thanks for all the info guys, I'll print it and give it to him, then
he can decide if the tv is worth another $200, and if he can even do it.

 

[amdx]

On 3/13/2015 1:32 PM, DaveC wrote:

"The entire screen had randomly scattered but stationary black and white
dots. Maybe about the size of the comma on your keyboard or just a little
larger. On one scene with a grey screen, and the Black and white spots, it
looked like one of the garage floors painted grey with the specks thrown on
it. Almost exactly like that."

Mikek

Like this? ::

https://www.youtube.com/watch?v=bGg_P1PqCYo

ShopJimmy has DLPs available for most back-projection TVs.

Good luck.

Yes, but much, much, worse, the whole screen area is covered.
Mikek