Is this a symptom of faulty backlight?

[rardhian]

Hi everyone,

I'm getting more curious about my T23. So, I managed to upload a few shots of it, displaying a gray background from several angles. The keyboard is located at the bottom (cannot be seen because of dark environment, and I forgot to turn the ThinkLight on :p).

http://students.if.itb.ac.id/~if23053/images/bl1.jpg
http://students.if.itb.ac.id/~if23053/images/bl2.jpg
http://students.if.itb.ac.id/~if23053/images/bl3.jpg
(sysop edit: please no embedded images )

1) Do you think it's faulty backlight (i.e. aging backlight bulb)?
2) Since the backlight is positioned at the hinge (please correct me if I'm wrong) then backlight fault WILL NEVER produce brighter light at the top. Is it true?
3) Having tried several white point temperature with Adobe Gamma Correction utility, I've managed to get white display, but still uneven (like on the pictures). At some view angle it will produce white at the top, but yellow(ish) at the bottom. Viewing it with lower angle will produce blue(ish) at the top, but white at the bottom. Does it also suggests (1)?
4) Where can I get the backlight bulb? And how much does it costs? (Found for $25 at eBay, new. Is it too expensive?)

[BillMorrow]

hard to say if it IS a backlight but it sure looks to be so..

and, no, IMO $25 for a replacement that is new is not too much..

[dvorak]

Unfortunately the display will not be equal regarding brightness on the top and bottom, I myself am rather annoyed by this, not to mention other LCD problems, and am interested in getting mine replaced with the newer Hydis' displays.

But if you're seeing yellow while the screen is white, that seems a bit suspicious, I agree, it's not even, but not THAT bad ;)

[Ted_E]

[quote="rardhian"]Hi everyone,

I'm getting more curious about my T23. So, I managed to upload a few shots of it, displaying a gray background from several angles.
...
1) Do you think it's faulty backlight (i.e. aging backlight bulb)?

Yes.

2) Since the backlight is positioned at the hinge (please correct me if I'm wrong) then backlight fault WILL NEVER produce brighter light at the top. Is it true?

No. My T23 screen is very evenly illuminated.

Ted

[dvorak]

Regarding the pictures, did you take them without flash?
Perhaps you could make a higher resolution one, straight, a bit hard to compare with the current pictures.

2) Since the backlight is positioned at the hinge (please correct me if I'm wrong) then backlight fault WILL NEVER produce brighter light at the top. Is it true?

No. My T23 screen is very evenly illuminated.

Ted

What resolution does your computer have?

I think this is more related to perception, all of the laptops I have seen have uneven displays - Older T40-s, T42s, other brands.

[Ted_E]

<< No. My T23 screen is very evenly illuminated.

< What resolution does your computer have?

1034x768 T23

< I think this is more related to perception, all of the laptops I have seen have uneven
< displays - Older T40-s, T42s, other brands.

Maybe I was just lucky. Both my 385XD and my T23 exhibit very uniform illumunation and I am very fussy about color matching and such things. I don't have a good light meter so I can't give any spot readings. I suppose I could take a digicam pic of the full screen white I described but I don't have anywhere to post it.

Ted

[dvorak]

Maybe I was just lucky. Both my 385XD and my T23 exhibit very uniform illumunation and I am very fussy about color matching and such things. I don't have a good light meter so I can't give any spot readings. I suppose I could take a digicam pic of the full screen white I described but I don't have anywhere to post it.

Ted

Thanks but I don't think a picture would help much in such a delicate comparision :P
Just FYI, imageshack.us, rapidshare.de, uploadit.org should help with hosting.

I'm still rather sceptical, it is harder to spot it with white color, but in my experience green and violet should display the inconsistency better.

[Ted_E]

Maybe I was just lucky. Both my 385XD and my T23 exhibit very uniform illumunation and I am very fussy about color matching and such things. I don't have a good light meter so I can't give any spot readings. I suppose I could take a digicam pic of the full screen white I described but I don't have anywhere to post it.

Ted

Thanks but I don't think a picture would help much in such a delicate comparision
Just FYI, imageshack.us, rapidshare.de, uploadit.org should help with hosting.

Thanks.

I'm still rather sceptical, it is harder to spot it with white color, but in my experience green and violet should display the inconsistency better.

Get that software I mentioned and try it. Note that by playing with the sliders I mentioned you can get any color the system is capable of. I tried various shades of violet and green. I saw some variation in intensity but by moving my position I could see that it was, mostly if not all, due to varying viewing angle. I don't notice it to any extent when looking at a photo or screen full of stuff but it is more noticeable with a solid color.

Ted

[rardhian]

No, no flashlight was used when taking those pictures.

I'm using `Dead Pixel Buddy', you can get it at http://www.laptopshowcase.co.uk. It is just several KBs and very useful for checking dead pixels.

Back to the topic, it is very hard to see the inconsistency with pure 'red', 'blue', or 'green'. It is also hardly noticable with pure 'white', but as with the color, you can really say that it's yellowish.

Somehow, it is VERY EASY to distinguish the highly uneven brightness (and a slight color difference produced at the top and the bottom of the screen) with some grey color (e.g. R:200, G:200, B:200).

[dvorak]

I think we mean the same thing, the screen itself may be quite consistent, but I've nevern seen it be consistent when viewing from one angle.
And that qualifies as enourmously bad vertical viewing angle, can't even get color consistency when watching straight at it - top does look a bit darker, move your head a bit up, top goes normal, all below a bit brighter.

And Ted_E, I don't see any software suggestions :)

[rardhian]

dvorak, on your Thinkpad, did the inconsistency ONLY affects the brightness of the screen area? Because on mine, it also affects the color, i.e. brighter part will be displayed yellowish, darker part will be displayed bluish.

It is possible to fix it by curving the display backwards. Assuming we're viewing the display on a fixed distance, the curve radius can be calculated. For now, I have to view the display from about 4-5 meters of distance to get uniform color across entire screen .

(Or maybe mine was incorrectly curved???)

[dvorak]

dvorak, on your Thinkpad, did the inconsistency ONLY affects the brightness of the screen area? Because on mine, it also affects the color, i.e. brighter part will be displayed yellowish, darker part will be displayed bluish.

Well, hard to explain, difference in brightness does produce different colors for my eyes.

For example, screen full of RGB(128;128;255) looks on the top like the Login background of Windows, and the top is a bit darker than the background on this post.
When I move a few meters back, it gets more uniform. A clear issue of bad vertical viewing angles.

Aggravtes me and definitely requires another trip to IBM's.

[AbsoluteRaleigh]

1) Do you think it's faulty backlight (i.e. aging backlight bulb)?

Yes.

Bulbs only last so long. That one is 3yrs old. It has life left to it and I wouldn't call it faulty but it isn't getting any younger.

[rardhian]

Thanks for replying guys, but I have my T23 replaced yesterday. The newer one is less yellowish. Having them compared side by side, it displayed bright white!! The person from the store didn't think that any of them is yellowish, though :p. But that's ok for them to replace mine. This one has very much better overall condition, anyway. It almost looked like new!

Assuming peoples are lazy to update the BIOS, I think it's younger than the previous one (the BIOS was dated 2002, where mine yesterday dated 2001). They're all dated 2004 now, after BIOS upgrade.

1) Can I findout the product or manufacture date for this Thinkpad (other than assuming BIOS date=product date)?

2) Is there any uptime counter? I.e. information about how long this T23 has been used. Because there is one my Siemens CX65 cellphones...

3) As for the uneven backlight, *all* of them (all 5 T23s) are uneven. Unfortunately I forgot to check other brands

4) Yesterday when I brought it home I've noticed 3 (white) dead pixels at the bottom of the screen. Wiped it several times and they're still there. But this morning, after I've cleaned the entire display, they all seem gone! Displaying red, green, blue backgrounds, they are really vanished! Are they really dead pixels?

5) But as using it more and more... I really think the display is still yellowish? Though maybe not as bad as the previous. Do you think backlight bulbs became yellowish gradually (and very slowly)?

6) Or was it really something wrong with my eyes? Can I see ghosts? Have you ever seen person with 4 legs? Are they ghosts?

IBM Indonesia said they sell the backlight bulb for around $65, but didn't have them on stock. Those person selling it for $25 on eBay refused shipping it to my country :p Hehe.. But perhaps I don't need them for now!