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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
Precision M4300 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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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
Precision M4300 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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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
Precision M4300 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

Still NOT a great day for a Guinness! (the Real Black Stuff).
Ireland is on FULL lockdown until Easter 2021!
Covid-19: Stay safe, so Mask it or Casket!

kfzhu1229
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Re: WTB: 15.4" CCFL backlight tubes

#5 Post by kfzhu1229 » Thu Jan 14, 2021 1:14 am

Well got another one of these Samsung WUXGA panels from another parts Dell that I got. This one is in pristine shape so I thought I should just use this instead... Aaand it seems like this CCFL tube starts to quickly degrade with a week or 2 of regular usage. So I ordered from that LCDparts store anyway. It was not cheap with the postage to Canada, but I made the most out of that postage thing with buying 4 tubes in total.
The installation well is actually more difficult than the IAUX14S panels from A3x. Was it just me or that this forum was down for an hour or two so that I can't open up guides for the IAUX14S CCFL replacements.
Fortunately I already have replaced backlight on this panel before and I have a bad one to practice for (heavily degraded pixels - not fixable).
On this panel there is a bigger bracket on top of the smaller bracket that contains the CCFL, and it has some annoying tabs to deal with that I always have to break my nail every single time.
Annoyingly this panel you HAVE to separate the layers because the white sheet and the light guide must push downward for the metal bracket to line up properly and I learnt that the hard way.
Fortunately this time around I know to do that first so the metal bracket came in without a single kink in it (a kink in that would make for uneven backlighting).
I have also tested this CCFL before hand with a wire harness stripped out of another panel onto this and fortunately the smooth brightness level changes are all working.
Took me 3 tries to fully assemble as one time the internal layers was not lined up correctly and another I see fingerprints on the light guide.
To my surprise though, this tube is really really cold in colour temperature. I'm perfectly fine with that.
The other thing is the LCDParts tube is also really bright - so much so that the inverter is not having it at maximum brightness with flickering. Fortunately all Dell screens come bundled with inverters and 14" and 15.4" widescreen inverters are interchangeable so I salvaged one off a 14" widescreen designed for 200nits of brightness and that did the trick.
Since I have to separate the layers, some spots got in and I believe more will come behind the screen too. Is it even possible to replace the backlight on the IAUX14S by hand without any minor imperfections like dust marks or backlight imperfections?
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 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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Re: WTB: 15.4" CCFL backlight tubes

#6 Post by kfzhu1229 » Wed Feb 03, 2021 11:36 pm

Okay well I think I got a lemon out of that order.
It's been like a month since I have installed that CCFL bulb, and it's dying. Initially I get a loud buzzing sound from the inverter so I ended up stuffing some cotton balls to mute it. And then the backlight started becoming really uneven at lower brightness levels, and now it does that at all brightness levels and gets too distracting. This is right after the 30 day return period... Luckily I bought two of them so I am using the other one now, but that means the poor screen has to go through another surgery...
The second one is so far so good I guess.
Also a couple of things that I am a bit unsure about in this one:
1. Is there polarity for the CCFL bulb itself? I see both sides have the same electrode and I have seen some people saying online that it's only the CCFL cable that has polarity due to its high voltage.
2. I noticed on most inverters (my T43p one too) has a potentiometer. I have searched online and yielded no results to what it actually does. What does it do?
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 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

#7 Post by TRS-80 » Thu Feb 04, 2021 9:54 am

Read through with interest, as old, fading backlight seems to be main limiting factor in keeping these old machines alive.

You prefer CCFL to LCD?
All good things are Wild and Free.

What is free software and why is it so important for society?

(2021) Actively on the lookout for for 15" T60 FlexView / Hydis LED displays and parts, for my own usage. Kindly PM me your demands if you are willing to part with anything. :D

kfzhu1229
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Location: Toronto, Canada

Re: WTB: 15.4" CCFL backlight tubes

#8 Post by kfzhu1229 » Thu Feb 04, 2021 2:32 pm

TRS-80 wrote:
Thu Feb 04, 2021 9:54 am
Read through with interest, as old, fading backlight seems to be main limiting factor in keeping these old machines alive.

You prefer CCFL to LCD?
No but I kinda don't have a choice here. I don't wanna do any LED modding to this stuff because it defeats the point of me using such a machine.
Well much of this has to blame with Samsung having crap quality display panels back then, even for this high end WUXGA one. The image quality while not bad, is worse than the LG panels back then, and I got 3 of these same Samsung panels with 1 with red backlight, and 2 with uneven backlights, and one of them also have the panel itself completely crapping out.
The LG WSXGA+ screen that I have on another one of these machines has none of these problems, even if I use it out in -10C environment.
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 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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