X6X-series LED backlight conversion kit howtos

X60/X61 series specific matters only.
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rthur
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Re: X6X-series LED backlight conversion kit howtos

#181 Post by rthur » Fri Jan 22, 2016 9:47 pm

I've (finally) acquired a new SXGA screen to start working on this after cracking the previous panel I had.

I already have a modified XGA frame in which the SXGA LCD layer fits nicely, so I'll be using that - this way I can actually mount the panel to the hinges properly.

What's the current best regarding which layers to use to avoid the LED pattern on the bottom of the screen?
I have a spare XGA screen I'm willing to sacrifice, and I'm not too concerned about losing a bit of brightness.

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Re: X6X-series LED backlight conversion kit howtos

#182 Post by xiphmont » Sat Jan 23, 2016 4:37 pm

rthur wrote:I've (finally) acquired a new SXGA screen to start working on this after cracking the previous panel I had.

I already have a modified XGA frame in which the SXGA LCD layer fits nicely, so I'll be using that - this way I can actually mount the panel to the hinges properly.

What's the current best regarding which layers to use to avoid the LED pattern on the bottom of the screen?
I have a spare XGA screen I'm willing to sacrifice, and I'm not too concerned about losing a bit of brightness.
If you hold on for a few days, I may have an Ultimate Solution...
[trying out new wide-angle LEDs on close packed strips...]

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Re: X6X-series LED backlight conversion kit howtos

#183 Post by rthur » Sat Jan 23, 2016 4:48 pm

xiphmont wrote:
rthur wrote:I've (finally) acquired a new SXGA screen to start working on this after cracking the previous panel I had.

I already have a modified XGA frame in which the SXGA LCD layer fits nicely, so I'll be using that - this way I can actually mount the panel to the hinges properly.

What's the current best regarding which layers to use to avoid the LED pattern on the bottom of the screen?
I have a spare XGA screen I'm willing to sacrifice, and I'm not too concerned about losing a bit of brightness.
If you hold on for a few days, I may have an Ultimate Solution...
[trying out new wide-angle LEDs on close packed strips...]
Awesome, will do!

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Re: X6X-series LED backlight conversion kit howtos

#184 Post by wileE » Mon Feb 01, 2016 1:57 pm

xiphmont wrote: If you hold on for a few days, I may have an Ultimate Solution...
[trying out new wide-angle LEDs on close packed strips...]
Any news? The world is waiting. You cannot say Ultimate Solution, and then go quiet.

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Re: X6X-series LED backlight conversion kit howtos

#185 Post by xiphmont » Mon Feb 01, 2016 4:49 pm

wileE wrote:
xiphmont wrote: If you hold on for a few days, I may have an Ultimate Solution...
[trying out new wide-angle LEDs on close packed strips...]
Any news? The world is waiting. You cannot say Ultimate Solution, and then go quiet.
Ooo, I suppose you're right :-)

I'm still working on making my custom strips and I'd not said more because I hadn't gotten back to it in the intervening time. Supposing calculations are correct (and they never are exactly) the strips and new LEDs should give better color than the original CCFL (wider gamut, though still not quite 100% sRGB coverage) at 600 nits or better. And I'm hoping there will be no bottom edge pattern, without the need to mess with films.

The downside is the LEDs are expensive. Cost of materials alone is $28/strip given my lack of quantity buying power. And they're tricky to make in that I'm still making the assembly guide, not sure yet if it will work.

[they mysterious delay is that the kids bring home two fresh viruses from school every week, all winter...]

When I posted the 'ultimate solution' message I was hoping to have a working test strip that afternoon. Oops.

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Re: X6X-series LED backlight conversion kit howtos

#186 Post by wileE » Mon Feb 01, 2016 6:03 pm

xiphmont wrote: When I posted the 'ultimate solution' message I was hoping to have a working test strip that afternoon. Oops.
The real life stuff getting in the way of tinkering with electronics?

Did you make your own printed circuit board strip for the new LED strips?

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Re: X6X-series LED backlight conversion kit howtos

#187 Post by flyingfishfinger » Tue Feb 02, 2016 4:11 am

The downside is the LEDs are expensive.
Which LEDs did you end up using? And I'm sorry about the Nichias...that was a bit of an expensive experiment too, no?

R

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Re: X6X-series LED backlight conversion kit howtos

#188 Post by xiphmont » Tue Feb 02, 2016 5:28 am

flyingfishfinger wrote:
The downside is the LEDs are expensive.
Which LEDs did you end up using? And I'm sorry about the Nichias...that was a bit of an expensive experiment too, no?

R
I'm still working with the Nichias. Nothing's gone wrong, it's more that nothing has gone at all yet.

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Re: X6X-series LED backlight conversion kit howtos

#189 Post by flyingfishfinger » Tue Feb 02, 2016 3:26 pm

Ah. Last I checked I thought the remote phosphor idea wasn't working too well. Or maybe I'm misremembering. Either way, good luck and keep us updated!

R

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Re: X6X-series LED backlight conversion kit howtos

#190 Post by xiphmont » Tue Feb 02, 2016 6:09 pm

flyingfishfinger wrote:Ah. Last I checked I thought the remote phosphor idea wasn't working too well. Or maybe I'm misremembering. Either way, good luck and keep us updated!
True that, the remote phosphors didn't work well enough.
There were two sets of samples I'd gotten from Nichia, the royal blues (to test with remote phosphor) and some brand new component phosphor LEDs specifically for backlight applications that they just released middle of last year. They sell them by specific color, voltage and luminance sub-bins (even to hobbyists! Score!) They're remarkably spiffy in numerous ways. Those are the ones I'm trying to make into custom strips.

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Re: X6X-series LED backlight conversion kit howtos

#191 Post by wileE » Fri Feb 05, 2016 11:01 am

@xiphmont
I have a little problem with the early 2015 TLD2 board.

On (so far tested) two X61 boards it will not dimm. LEDs run at full brightness. It works fine on two other boards I tested.
And other LED kits (also a TLD2 late 2015) will work on the boards that do not dimm with that one TLD2.

Swapped all other parts that could possibly be involved several times, checked my wiring on the board :), tested on battery and AC., tested in BIOS, Windows and Linux.

Do you have any explanation for what could cause that behavior?

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Re: X6X-series LED backlight conversion kit howtos

#192 Post by xiphmont » Sat Feb 06, 2016 1:38 am

wileE wrote: Do you have any explanation for what could cause that behavior?
Well, most likely is probably "It's busted". This is one of the ones with R3 removed?

Another possibility: make sure the + pad for the LED output is not shorted to the output capacitor right above.

Also, just hit a nice milestone: With a little practice, a stereo microscope and a pneumatic dropper to get better consistency on the solder paste, I just made my first flawless prototype with the new LEDs. I'm going to see if I can peel off a few more. then start testing in an actual HV121P01-100.

[edit: 3/3 flawless assembly tonight. In-screen testing tomorrow!]

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Re: X6X-series LED backlight conversion kit howtos

#193 Post by pkiff » Sat Feb 06, 2016 10:19 am

xiphmont wrote:Also, just hit a nice milestone: With a little practice, a stereo microscope and a pneumatic dropper to get better consistency on the solder paste, I just made my first flawless prototype with the new LEDs. I'm going to see if I can peel off a few more. then start testing in an actual HV121P01-100.
[edit: 3/3 flawless assembly tonight. In-screen testing tomorrow!]
Sounds promising! Keep up the good work. Continuing to follow with bated breath.
W520 (dual-boot Windows 10/Ubuntu 15) · X61 Tablet SXGA+ · T60p UXGA · Legacy: X60T, 600X, 770Z
Thinkpad Media Centre: X61T running XBMC with Broadcom Crystal HD BCM970015, Creative X-Fi Surround 5.1 plugged into Cambridge Audio Sonata AR30 receiver

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Re: X6X-series LED backlight conversion kit howtos

#194 Post by wileE » Sun Feb 07, 2016 10:02 am

xiphmont wrote: Well, most likely is probably "It's busted". This is one of the ones with R3 removed?

Another possibility: make sure the + pad for the LED output is not shorted to the output capacitor right above.
Yes it the one with R3 removed. It is just strange that it works on some boards and not on others.
The soldering on the + pad and the C6 do not touch, but there is 0 resistance between those pads anyway. Is that as it should be?

xiphmont wrote: Also, just hit a nice milestone: With a little practice, a stereo microscope and a pneumatic dropper to get better consistency on the solder paste, I just made my first flawless prototype with the new LEDs. I'm going to see if I can peel off a few more. then start testing in an actual HV121P01-100.

[edit: 3/3 flawless assembly tonight. In-screen testing tomorrow!]
Looking forward to hearing about the results. And pictures!

Microscope and pneumatic dropper?
You should have called it: ULTIMATE SOLUTION*

*only for advanced engineers with very steady hands

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New backlight strip proto update

#195 Post by xiphmont » Wed Feb 10, 2016 10:10 am

A quick update from lots of testing with my various strip prototypes using the new Nichia LEDs, all of it torward having the best possible
option for the SXGA+ screens...

The good news is pretty good.

Color saturation exceeds the original backlight on all primaries! No more washed out red/green. White is spot on the daylight locus and
slightly cold (~6900K) for the SXGA+ screens. It's better to be too cold than too warm, as most of the fitting adjustments, spacing and
shimming tend to warm the light a few hundred K. So the end resulthere should be perfect.

Light output at 335mA (same as the other strips) is an absolutely absurd 488 nits measured. The best part is that these LEDs have a
really low Vf for whites, so the actual electrical power was only about 2.5W. That means at a real 3W of output, the original output
target, that's almost 600 nits. Even at 3W, the LEDs are only pulling 12mA each and they're actually rated for 150mA. Thermal
dissipation is the real limit, but I've been testing them at a little under 5W which seems to be going fine... and that delivers close to 1000 nits.

That's for-real, installed in an actual screen. So, holy wow.

I'll probably have to sacrifice a little bit of that brightness to space the strip back a little from the waveguide in order to eliminate
the last of the discrete LED pattern along the bottom of the screen. The strips aren't too bad to begin with-- the close packing (81 LEDs
in a strip with no spacing at all between them) and the output pattern of these LEDs alone eliminates about 90% of the pattern problem. I can
eliminate the rest if I just find the right way to fit it, because I've done it by accident a few times ;-)

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Re: X6X-series LED backlight conversion kit howtos

#196 Post by wileE » Wed Feb 10, 2016 12:16 pm

That sounds very good. Are you nearing the end of your search for the best possible SXGA+ backlight? Or are RGB LEDs next? :D

You seem to be using one the NSSW157 ?? LEDs. Which type?

And I cannot figure out how you get a working strip with 81 LEDs. Are you still using groups of 3? A picture of the soldering setup would be welcome.

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Re: X6X-series LED backlight conversion kit howtos

#197 Post by flyingfishfinger » Wed Feb 10, 2016 3:07 pm

+1. Pics pics pics! Your work is impressive. My projects ran head-on into Chinese new year, so I'm watching other people's with great interest :)

R

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Re: X6X-series LED backlight conversion kit howtos

#198 Post by xiphmont » Sat Feb 13, 2016 3:41 pm

That sounds very good. Are you nearing the end of your search for the best possible SXGA+ backlight? Or are RGB LEDs next? :D
I think we're close to the end... and these are RGB LEDs in a sense. They're blue LEDs pumping component green and red phosphors. They're not the typical blue led / yellow phosphor combination. There's almost no yellow output at all.
You seem to be using one the NSSW157 ?? LEDs. Which type?
Yup! NSSW157FT-HG color bin Btc72, output bin P10d22. Spec sheet here: NSSW157F-HG-E.pdf
And I cannot figure out how you get a working strip with 81 LEDs. Are you still using groups of 3? A picture of the soldering setup would be welcome.
27 groups of 3 == 81 LEDs, fits into 250mm exactly :-)

Pics. Oh, hm, OK... Let me work on that a bit.
/me looks at his federal disaster area of a desk...

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Re: X6X-series LED backlight conversion kit howtos

#199 Post by wileE » Sun Feb 14, 2016 9:19 am

xiphmont wrote: 27 groups of 3 == 81 LEDs, fits into 250mm exactly
Still wondering what PCB you are using. Did you have some made for the 81 LEDs?

The price of those LEDs for small numbers is not so great. I was thinking of maybe trying to put them on the strips from creatall (with the horrible, unusable yellow-green LEDs). Better colors would be very welcome.
Although that would not solve the pattern problem I have in one of my SXGA+. But building a strip with 81 LEDs is simply impossible for me, and most likely for everyone else still using the X61.

Are you gong to do measurements like on this page: https://people.xiph.org/~xiphmont/think ... amut.shtml?

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Re: X6X-series LED backlight conversion kit howtos

#200 Post by xiphmont » Tue Feb 16, 2016 12:01 pm

wileE wrote: Still wondering what PCB you are using. Did you have some made for the 81 LEDs?
Sorry for the incompleteness of the last post, I realize I only answered one question... I'm currently traveling (family visit to granny's in Toronto) and I was busy getting ready. Some pics when I get back.

I made new PCBs, yes. 3pcb was not only willing to make PCBs only 1.8mm wide as a standard request, they even did a pretty good job. At least, the the strips they made me were nicer than many of the Chinese strips I've bought with kits. They were ~ .80 apeice at quantity 100, and I made them trim-to-length like the other manufacturers, so I can also make strips for larger screens if I want.

The LEDs have captive/hidden pads on the bottom, and I've packed so that they're mostly touching, so the entire soldering job is a hidden assembly. I place the paste, then the LEDs on the paste using tweezers under a microscope, then preheat and reflow on a cheap but really quite decent Chinese hotplate. I milled a custom placement placement/soldering jig for the place/solder steps and have it all very nicely dialed in now. It takes me about half an hour to make one strip by hand start-to-finish, which is actually a good bit faster than I was managing before. The process thus far has been entirely reliable now that I've practiced a bit.
wileE wrote: The price of those LEDs for small numbers is not so great. I was thinking of maybe trying to put them on the strips from creatall (with the horrible, unusable yellow-green LEDs). Better colors would be very welcome.
Although that would not solve the pattern problem I have in one of my SXGA+. But building a strip with 81 LEDs is simply impossible for me, and most likely for everyone else still using the X61.
These Nichia LEDs are a good 10x more expensive than just about anything else I've seen. I bought a reel of 5000, which is more than I have a personal need for, so I had planned to make up a bunch of strips and sell them at cost. But first I need to figure out the last of the placement riddle.

Conceptually, it's not hard-- the easiest approach needs an air gap of about .5-1mm between the strip and the waveguide to make the pattern disappear. A clear spacer strip doesn't work the same, it preserves the reflections. So I've been playing with accordion folds, punching, or heat molding a strip that will enforce the air gap without taking up the entire space itself.

It also occurred to me that I could probably laser-cut a clear spacer strip in a pattern to counteract the unwanted pattern with a new pattern that could cancel it out.
Are you gong to do measurements like on this page: https://people.xiph.org/~xiphmont/think ... amut.shtml?
Yes. I already made measurements actually, but the final placement and fitting will affect the results, so those were just to get a starting point.

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Re: X6X-series LED backlight conversion kit howtos

#201 Post by wileE » Wed Feb 17, 2016 3:44 pm

Thank you for the explanation. I do admire your determination to build the best possible backlight.

And if you do make some strips to be sold, I am of course interested in one or two.
xiphmont wrote:But first I need to figure out the last of the placement riddle.

Conceptually, it's not hard-- the easiest approach needs an air gap of about .5-1mm between the strip and the waveguide to make the pattern disappear. A clear spacer strip doesn't work the same, it preserves the reflections. So I've been playing with accordion folds, punching, or heat molding a strip that will enforce the air gap without taking up the entire space itself.

It also occurred to me that I could probably laser-cut a clear spacer strip in a pattern to counteract the unwanted pattern with a new pattern that could cancel it out.
I do not think there is one method that will work on all SXGA+. I have found them to be very different with the same LED strip.
Some are a tight fit, others have more than a millimeter of spare room when the strip is inserted. On some the bottom pattern is easily avoided when the strip is placed in just the right angle, and with others there seems to be no way at all to get a decent result.

I think with your gapless strips a lot of SXGA+ should be fine without any effort.

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Re: X6X-series LED backlight conversion kit howtos

#202 Post by xiphmont » Wed Feb 17, 2016 4:39 pm

wileE wrote:Thank you for the explanation. I do admire your determination to build the best possible backlight.

And if you do make some strips to be sold, I am of course interested in one or two.
Even if the spacer ideas fail, this is still a pretty good solution. I just want to make it perfect :-) I will have strips to sell either way.
wileE wrote: I do not think there is one method that will work on all SXGA+. I have found them to be very different with the same LED strip.
Some are a tight fit, others have more than a millimeter of spare room when the strip is inserted. On some the bottom pattern is easily avoided when the strip is placed in just the right angle, and with others there seems to be no way at all to get a decent result.

I think with your gapless strips a lot of SXGA+ should be fine without any effort.
The depth to which the plexiglas waveguide extends into the backlight bracket makes quite a bit of difference. I've been experimenting here both on waveguides in-situ as well as naked outside the screen just sitting alone on my desk. The absence of a bracket eliminates much but not all of the ripple. So... the ripple is coming from a couple of different places and smalll changes in assembly can alter it quite a bit.

If you'd like a strip or two with which to experiment, I can certainly oblige. If you declare it good enough, perhaps I will just decide that you're right.

[I *was* looking forward to an excuse to try a laser cutter though]

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Re: X6X-series LED backlight conversion kit howtos

#203 Post by rthur » Wed Feb 17, 2016 9:54 pm

Awesome progress - looking forward to having one of these!

Are the LED strips rigid enough that fixing them on either end would be enough?
We could make some small rubber holders, similar to the the rubber boots that hold the CCFL in.

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Re: X6X-series LED backlight conversion kit howtos

#204 Post by wileE » Thu Feb 18, 2016 10:45 am

xiphmont wrote: [I *was* looking forward to an excuse to try a laser cutter though]
Please, do not let me discourage you.
A lot of people would be happy if you find a solution to the pattern problem. It is not just the X6x AFFS screens, the 15.4" WSXGA+ and WUXGA Samsung screens in the
T61 and T/W500 are just as bad. The QXGA and UXGA in the T60 and Frankenpads even much worse.
xiphmont wrote: If you'd like a strip or two with which to experiment, I can certainly oblige. If you declare it good enough, perhaps I will just decide that you're right.
No, I do not think you would. As long as there might be a solution, any idea would have to be tested.

Those new strips you made scare me a little, because all the old mods might look intolerable compared to them. It's hard to stop at good enough.

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Re: X6X-series LED backlight conversion kit howtos

#205 Post by xiphmont » Thu Feb 18, 2016 11:09 am

xiphmont wrote:The depth to which the plexiglas waveguide extends into the backlight bracket makes quite a bit of difference.
Actually, there's another thing I noticed--- some of the backlight brackets have a yellowish tint to the reflector film. I've only seen it on XGA screens, and I originally thought it was yellowing due to age. Given the materials though (metallized BoPET) I don't think it can be age, it must be intentional. I've never seen it on an SXGA screen. That would make a huge difference to the color and brightness as well if it ever showed up.
rthur wrote:Awesome progress - looking forward to having one of these!

Are the LED strips rigid enough that fixing them on either end would be enough?
We could make some small rubber holders, similar to the the rubber boots that hold the CCFL in.
They're semi-rigid and bendable like the other strips you've seen, so that's a possibility given a little effort to bend them perfectly flat for fitting. I also considered using little o-rings around the strips like are used on the CCFL tubes. I hadn't tried that because I was worried about the spacing being too large, but I probably should. It could work.

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Re: X6X-series LED backlight conversion kit howtos

#206 Post by wileE » Fri Feb 19, 2016 12:20 pm

xiphmont wrote: Actually, there's another thing I noticed--- some of the backlight brackets have a yellowish tint to the reflector film. I've only seen it on XGA screens, and I originally thought it was yellowing due to age. Given the materials though (metallized BoPET) I don't think it can be age, it must be intentional. I've never seen it on an SXGA screen. That would make a huge difference to the color and brightness as well if it ever showed up.
The XGA TN HT121X01-101 in the X61 has a bracket that has what I would call a golden tint.
I'm not sure about the XGA AFFS BoeHydis in the tablets, but it is possible they have that type of surface in the bracket too. I cannot say that I noticed any significant difference in the colors between the XGA and SXGA+.

The Samsung LTN121XJ-L07 XGA in the X61 has a matte white surface in the bracket.

As long as the spectrum of the backlight allows for a decent calibration of the screen, it does not really matter.

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Re: X6X-series LED backlight conversion kit howtos

#207 Post by xiphmont » Mon Feb 22, 2016 4:17 pm

As a quick update: I still owe you all pictures ;-)

I've settled on up-powering the TLD1 driver board for the new strips with a .332 ohm current sense and 47uH coil for higher current. That's giving an output of about 595mA for around 4.75W output at 4.9W total power consumption at full brightness (juuust slightly higher than the draw of the original inverter/CCFL). The fittings done using a 5mil accordion-fold boPET spacer are currently the best performing in terms of the intensity/pattern-elimination tradeoff:

the usual LARGE Gamut test pic: https://people.xiph.org/~xiphmont/think ... ordian.png
LARGE original CCFL measurement for comparison: https://people.xiph.org/~xiphmont/think ... 0-CCFL.png
best previous LED strip measurement (an uncommonly good strip from iCCFL): https://people.xiph.org/~xiphmont/think ... l-best.png
(the iCCFL strip is being run at 335mA there; at equivalent power to my prototype, it would put out about 500-520 nits, though only briefly since it would likely burn out. It also has an unusable level of LED reflections; the proto measurement above sacrifices about 80 nits to show no LED reflections at all)

All the fitting techniques are getting results within about 10% of each other on any given matrix. That's good news in that the strips are not as super-sensitive to placement as some int he past have been (or I've just gotten better at it). I'm currently fascinated with shimming using a 6-mil teflon copolymer tape that isn't getting better results, but dang it's fun.

Oh, and the little o-ring spacers were a total bust. They shred way too easily. I never managed to get a single one into place before it disintegrated. Oh well, had to try :-)

More pics in a bit. And I still need to try laser-cutting a spacer....

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Re: X6X-series LED backlight conversion kit howtos

#208 Post by wileE » Mon Feb 22, 2016 5:44 pm

xiphmont wrote: the usual LARGE Gamut test pic: https://people.xiph.org/~xiphmont/think ... ordian.png
That is amazing. Real red and green colors, color temperature looks near perfekt for AFFS screen. And the brightness is just crazy. Dream outdoor usable X61T.
I do desperately want that for my Tablet.

Do the LEDs stay cool enough at full brightness?

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Re: X6X-series LED backlight conversion kit howtos

#209 Post by xiphmont » Mon Feb 22, 2016 9:55 pm

wileE wrote: I do desperately want that for my Tablet.
I assumed once I got good results, a few would be reserved with your name on them (along with flyingfishfinger and rthur). The LED strips themselves are now in final form.
wileE wrote: Do the LEDs stay cool enough at full brightness?
I haven't seen any reason to worry about temps so far. I don't have a temp sensor in the screens, but from watching the junction voltage, they're not getting particularly hot.

Now I'm just trying to nail down ease of installation and fit consistency, making sure everything works properly when others try to do it...

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Re: X6X-series LED backlight conversion kit howtos

#210 Post by flyingfishfinger » Tue Feb 23, 2016 3:20 am

xiphmont wrote:...when others try to do it...
Well that's what you have us testers for, yes? :D

R

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