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WTB: 15.4" CCFL backlight tubes

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kfzhu1229
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WTB: 15.4" CCFL backlight tubes

#1 Post by kfzhu1229 » Thu Oct 08, 2020 3:53 pm

As title says. I end up having two 15.4" WUXGA and one WSXGA+ screens with varying degree of backlight condition (one uneven on startup and gets better after a few minutes, one very uneven and seems to stay like that, one is a little bit red on startup but recovers after a few minutes even at the lowest brightness) and would like to get them replaced.
All are single backlight variants from some Dell Latitude D830's and Precision M4300's.
Is there anything significantly different about these backlights in terms of specs out of all the 15.4" CCFL tubes? These screens seem to support a smooth gradient of backlight brightness though. Do all of these 15.4" CCFL tubes support this?
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Lat D830 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)

kfzhu1229
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Posts: 1776
Joined: Tue Sep 22, 2015 10:59 pm
Location: Toronto, Canada

Re: WTB: 15.4" CCFL backlight tubes

#2 Post by kfzhu1229 » Fri Oct 16, 2020 11:39 pm

Well I think I can answer my question of whether all the 15.4" CCFL tubes are the same. And the answer is unfortunately no.
It seems like there is a difference between the PWM pulses of backlights of some screens over the others.
So right now I have a WXGA screen from a Toshiba and WSXGA+, WUXGA screens from Dell and apparently they are compatible with each other (provided the motherboard supports the EDID and the resolution) and the backlight works flawlessly. These screens are also capable of a smooth gradient of brightness levels.
However, I have a WXGA screen from an HP and a WSXGA+ screen from a MSI laptop and those on a Dell gives me trouble with the brightness levels. The screens then have the highest level of brightness at level 4 and dimmest at level 5. Tried the same screen on Dell and Toshiba laptops both give me the same problem. The screen itself works fine though on these laptops. Don't think these screen backlights are capable of that smooth gradient of brightness levels. When I touch that slider with these screens the brightness just goes immediately from lowest to highest brightness.
I am curious though to see which side of compatibility does the 15.4" ThinkPad screens lie on.
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Lat D830 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)

kfzhu1229
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Posts: 1776
Joined: Tue Sep 22, 2015 10:59 pm
Location: Toronto, Canada

Re: WTB: 15.4" CCFL backlight tubes

#3 Post by kfzhu1229 » Sun Oct 18, 2020 9:07 pm

Well I think I have also learnt a lesson in backlight replacement.
So it turns out that one of the WUXGA panels I have (the one that has a good backlight) is faulty. So I decided to swap the backlights, but after assembly the right 1/5 of the screen just fades darker and it annoys me more than I thought.
So I decide to try to reseat the metal gasket around the bulb. It turns out on this Samsung panel, you HAVE to separate the layers (peel off all the layers except for the light guide and the white sheet), and then push the light guide and the white sheet out to the back side of the display, exposing the bottom portion, and then the metal gasket must CLAMP the light guide and white sheet together before I can push everything back in and assemble.
I tried to align that metal gasket with the white sheet and the light guide by sliding a small flat head screwdriver across the seam of the gasket and then it puts too much pressure and the bulb cracked! It was an absolute mess to deal with! I have separated the top crystal layer on the other side so that doesn't get any of the damages fortunately.
I eventually found an AUO panel with a "broken" backlight that turned out to just have the solder joint on the CCFL chopped off by a cockroach before the cockroach got electrocuted to its death :lol:
This time doing what I said and pushing out the guide and the sheet, exposing them from the bottom allows for much easier alignment with the metal gasket before I can push everything in.
Now after assembly, aside from a bit of unevenness along the bottom from me deforming the gasket for my first attempt, everything lights up quite evenly now.
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Lat D830 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)

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Re: WTB: 15.4" CCFL backlight tubes

#4 Post by RealBlackStuff » Mon Oct 19, 2020 12:28 am

NOT a great day for a Guinness! (the Real Black Stuff).
Ireland is on FULL lockdown till December 2020!
Covid-19: Mask it or Casket!
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