The case of the disappearing stuck pixels on my Z2 - HELP

[KraGorn]

Having just bought a Z200 I was checking over my Z2 before putting it up for sale. From viewing distance nothing was visible, but up close I saw 3 isolated stuck pixels, two blue one green, randomly spread over the image .. no big deal, don't know if they were there when I got it, I'd not seen them before this inspection.

However there was also a cluster of at least 2 and possibly 3 stuck blues towards the bottom edge. Like the others, they made no impact on the picture quality but I figured a cluster isn't good if I'm wanting to sell it and in any case I was told by the dealer I bought it from that a cluster of 3 is definitely outside Sanyo's 'spec'.

So, I packaged it up and sent it off to Owl, Sanyo's distributor.

Today, I spoke to one of their tech. guys who says he can find NO STUCK PIXELS at all ... zip, nada, nothing is wrong. He said he'd run a 'white raster' then black, plus other tests and seen nothing. They'd shown the projector to a Sanyo rep. who also saw nothing.


I have no reason to think they're lying as if it is faulty then at worst case I'll get a third-party to swear to it and take it to court. Likewise I've no reason to lie either, especially as it cost me £35 to send it back which if it's faultless would be just flushing money down the drain. It's definitely the same machine, at least it's the same serial number as that I sent back.

So, can anyone think of something in my system unconnected with the projector that could produce results which look like stuck pixels? Right now it's sitting in Owl's Returns Department apparently faultless and unless some more extended testing reveals anything I'll have no option but to accept it back .. which doesn't get me anywhere.

 

[Andy.T]

Weird.

I don't suppose any kids have been running about near your screen with small blue/green stickers? Sorry.

I guess all you can do, if they're adamant they've found nothing is await it's return and say that you'll expect them to pick up the shipping if you get it back and the problem's still there. I'm not familiar with the Z2 but would it be possible to see the problem, with no cables/source plugged in? (Does it come up with a coloured screen while it's awaiting a signal?) That'd obviously prove it's not any other of your equipment.

You could always take a picture of the problem and e-mail it to them (if it's still there) when it returns.

 

[gothmog]

Bizarre

My AE300 does have a blue pixel that lights up with a dark grey but is completely absent on a black screen, could this be something similar?

-- Jon

 

[KraGorn]

Well the tech. said he's tried several tests, without and without colours, so in theory he's covered that possibility.

I've been trying to remember just what I had connected when I was analysing the screen, but of course I had no reason to be interested in the signal source at the time so have no idea.

Sadly I don't have a digi-cam and my real camera wouldn't resolve the cluster, let alone the individual pixels.

If no-one comes up with any ideas then I guess I'll have to accept it back un-touched .. thanks for the suggestion about shipping Andy .. and assuming the fault still persists try doing a lot more experimentation .. and borrow a digi-cam.

 

[Goof]

As it happens, I've been involved with something similar - sold a Philips Pj to a member of these forums and checked it over before selling that there were no pixel problems (which there wasn't).

On arrival at the other bloke's he commented that there were a couple of stuck pixels - my response was obviously one of surprise! However, a day or two later he mailed back to let me know they had disappeared

No idea how it happened but I guess it can - it seemed the transportation had been the cause that brought them out in my case, maybe they got rid of yours (just don't allow them to post it back ).

 

[KraGorn]

Goof, thanks for recounting that experience, it's certainly extremely similar to mine.

Hmmm .. wonder what courier would transport it without throwing it into the back of the van.

 

[KraGorn]

Well the Z2 came back, complete with a letter signed by a Sanyo 'field engineer' declaring no problems pixels or dust blob ...

... no-one will be surprised to hear I plugged it in, switched it on, and immediately was able to see the blob and on getting within 2 feet of the 92" screen see the stuck pixels, just as I'd described them.

Note Owl and Sanyo's stance is that there is no fault at all, not that there are flaws which fall within their 'acceptable' (sic) limits.

So, after spending £35 sending to Owl I'm having to spend another £35 to send it to the dealer I got it from .. I'm damned if I'm going to let Sanyo call me a liar!

Frankly these 'faults' aren't a problem, the pixels can't be seen beyond a couple of feet and the dust blob, like all of them, only appears when no picture is showing, as soon as some image is projected all these 'faults' disappear .. but it's now a matter of principle.

 

[Paul D]

Hi
Are you sure these are actually stuck pixels?
I thought i had several stuck pixels with my first LCD(MT1).

Dead pixels, look like black spots on their relevent colour background.
Ie, a dead blue pixel would need a blue background to show up properly etc.(Red for Red, Green for Green)

"Stuck On" pixels can have varying degrees brightness.
A black background is used for any of the colours.
A full "Stuck On" pixel, is easy to spot from nearly any distance back.
You will see a vivd coloured dot that will look sharp when the image focus is correct. (Going softer when out of focus etc)
Sometimes these "Stuck On" pixels come and go, and how hot the PJ is can effect them.

Partially "stuck On" pixels are rare, but again focus in and out relative to the image.

I have installed plenty of LCDs for friends/Family, and dust is the biggest cause for most of my "HELP! I've got stuck pixels!" callouts

This usually happens about a month into their ownership.
After the shock/delight of a large screen wears off, they start getting nearer to the screen to have a closer look.
This is when they see "phantom" stuck pixels.

Dust can cause specks of light(on a black background) to appear quiet bright. (they effect the way the poleriser plate works)
They can and do look very like stuck pixels, and come in all three colours.
Tell tale signs that they are in fact dust are as follows:-
Larger or smaller than the normal pixel size.
Fuzzy edges when the image is focused properly.(sharpening when the image is out of focus)
Some of these dust spots waver slightly due to the fan etc.
The exact same spots appear all over the screen, with some in clusters.

Apart from opening the case(or shipping it for service) and doing an "airblast" clean. You can try running the projector in full lamp mode, which normally makes the fan run faster. Or if you can control the fan, turn it up!
Make note of several "spots", and see if any disappear/move.

If you cannot see the spots from 1x1 screen widths, then:-
a - they aren't duff pixels
b - Even if they are, they aren't a problem!

If the above doesn't help, then maybe they are duff pixels and you have been very unlucky.
But remember, it is VERY rare(but not impossible) for pixels to fail in use. Normally duff pixels are there from new, and it is almost never heard of so many random pixels failing all at once.
They would normally be either all one colour, or in "lines" or "clusters" etc.

 

[KraGorn]

Well I don't know how else to describe what I see.

First, they're not visible beyond about 2-3 feet. However, up close I can see 1 green and 3 blue single pixels in the bottom right-hand quadrant, they're in the barely visible grid of pixels and are present when no connection is present to the projector or when an input signal is blank, eg. my 868 has no DVD in it. However, these aren't the main problem.

I also see a cluster of 2 or 3 in what looks like an 'L' shape, these are kind of hard to focus my eyes on from up close so I cant' be sure how many there are but they're definitely 2 pixels across and 1 or 2 down.

Sure, they're not visible beyond 2-3' but I want to sell it and if someone asks if there are any 'defective' pixels and I tell them there's a cluster the potential purchase is likely to run a mile since though *I* may say they're not affecting the PQ the description of this defect would make it sound a big deal.

That's why it's a big issue for me.

I appreciate the detailed description of pixel problems fulabeer, I'm a n00b when it comes to this sort of 'defect' so I may be using wrong terminology .. for instance I don't know what a 'lazy' pixel is .. but I'm trying to describe what I see, and that's some pixels that appear to be permanently lit.

 

[Paul D]

No probs, but try the focusing thing.
Focus either side of the normal "perfect" focus point for the image.
If the stuck pixels sharpen, instead of blurring when "off" perfect focus, then they are just dust.
It's commendable you are worried about selling a something you feel may be faulty(very rare these days!). But the guys at Owl know what they are doing, and i would be suprised if they were wrong.
Try to see somebody elses LCD (up close etc), and see if your spots look similiar.

 

[KraGorn]

Right, just did some testing .. what I'm calling 'stuck' pixels disappear when the focus is off even by only a relatively small amount. For instance, with just the menu if de-focus so that the text is just un-readable the stuck pixels have disappeared .. sharp focus and they come back.

However, whereas you say a stuck pixel would be viewable from any distance, these are invisible from further than about 2' on my 92" screen.

Edit:

Okay, I'm now more confused than ever.

First, the green stuck pixel has gone .. I didn't notice it before but it's not there any more. Second, the 'cluster' has changed shape, it's smaller, as if one of the suspected 3 stuck blues has also 'gone'.

I've checked the entire screen and no more have appeared since I first spotted these some weeks ago .. whatever these are I have a letter from a Sanyo tech. saying there's nothing wrong with the projector, so I don't think I'll spend any more money sending it away and sell it as-is.

 

[DVDcake]

I used to have a Panasonic PT-LC75 which when it was new appeared to have two or three individual stuck pixels of various colours (cannot remember which) but by the time I came to sell it two years later they had all disappeared. It had been used on low and high fan settings at various times so maybe it was due to dust which eventuallly got blown away.

 

[Bert Coules]

KraGorn,

Just to say that it was I who bought Goof's Philips projector and I can confirm the Mystery of the Vanishing Faulty Pixels. Very strange, but definitely true...

Bert
www.bertcoules.co.uk

 

[KraGorn]

I guess I'll never get to the bottom of it probably, if Owl and Sanyo say it's faultless then whatever I'm seeing isn't considered a fault. While on or two of the problem pixels may have 'gone away' on its' way down to Owl not all would, so some at least must have been present when they tested. Clearly what *I* consider a fault and what *they* consider a fault must be two different things.

When I sell it I'll just ensure potential purchasers are aware of them, and if they can't collect will give them a refund-period to avoid potential arguments, though I'd prefer them to see it so I can point out the problems and they can be sure they're not a 'problem'.