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 Post subject: LCD Blemishes
PostPosted: Sat Aug 27, 2011 12:15 pm 
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Joined: Mon Aug 22, 2011 5:59 pm
Posts: 17
Location: Phillipsburg, NJ
By LCD blemishes, I mean dark/dim spots on the display, specifically NOT including:

* broken pixels,
* dirt/stains on the front (outer) surface,
* backlight malfunction, or
* mechanical "pinch effects" (LCD response to pressure) such as are often seen at one or more corners.

The kind I mean are irregularly shaped blotches, usually with varying shading (gradations of darkening within the blotch). As someone who has bought a lot of used/refurbished Thinkpads over the years, I have seen these a number of times. I just got a T43 with a nice UXGA, but with a quite dark blotch shaped not unlike a candle flame, several millimeters tall.

Sometimes these seem to be dirt/contamination between the various layers, and sometimes mechanical dents (broad but not vary dark blotches with smooth gradation of shading). But I suppose there are other causes as well.

I would be grateful if any LCD gurus on the forum can advise about:

* diagnosing the cause of blemishes
* if it is practical to fix them, how to do it

Thanks!


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 Post subject: Re: LCD Blemishes
PostPosted: Sat Aug 27, 2011 3:26 pm 
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Moderator Emeritus
Moderator Emeritus

Joined: Thu Apr 12, 2007 8:23 am
Posts: 13228
Location: Upstate New York
Without seeing a picture of the actual blemish, I'd guess it was dust based on your description. FWIW, I have never seen anyone here report success in attempting to 'fix' that. I recall one post where it was attempted and failed. Assuming it could be cleaned, the major factor in taking an LCD that far apart is introducing more dust.


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 Post subject: Re: LCD Blemishes
PostPosted: Sat Aug 27, 2011 11:44 pm 
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Senior ThinkPadder
Senior ThinkPadder

Joined: Sun Feb 25, 2007 11:28 am
Posts: 12026
Location: Albrightsville, Pennsylvania
If the "candlelight" effect is in the corners of the screen, that's a backlight past its prime, extremely common on ID Tech UXGA panels.

If not, I'm with Harry...attempting to remove dust specs will likely have a destroyed panel as the end result.

_________________
...Knowledge is a deadly friend when no one sets the rules...(King Crimson)

Cheers,

George (your friendly retired FlexView farmer)

Collecting SSDI: A31p, T42p, T43p

Abused daily: T43pSF, T60, R60F, R500F

For sale: T61, T61p


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 Post subject: Re: LCD Blemishes
PostPosted: Tue Aug 30, 2011 10:32 am 
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Joined: Tue Jun 14, 2011 9:03 am
Posts: 71
Location: Delhi, India
I've only seen this once, on a used LCD screen I bought from eBay. My guess is that someone pressed their thumb really hard against the screen, causing permanent damage


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