Philips 46PFL8008S/12 to 55PFL8008S/12 screen upgrade (#P36)

Back in #P15, two years ago, I replaced the damaged screen of a Philips 46PFL8008S/12 Ambilight TV with a working one from a braindead unit. Classic failure mode of this generation, ideal opportunity for a 2-to-1 repair.
This week I’m going to upgrade the screen from 46″ to 55″. Because I can. And because the wall mount supports the larger unit (which of course I didn’t check beforehand…). And, funnily enough, because I earned ten bucks that way. And because a larger TV is slightly more entertaining in the rare event of watching a movie. In that very order.

Ever since the Ambilight chaining experiment in the previous post I wondered if screens can be interchanged within the 8008S series. After all, it’s the very same TV with no additional features except for a larger Ambilight (more on that later), same resolution, probably the same mainboard. It’s just that back then 66€ for a defective 46″ unit were a good deal and working ones went for several hundreds, 55″ was at a substantial premium for both types. Nowadays even defective 55″ are basically worthless, even though working ones go for a few hundred bucks. It seems FHD TVs are pushed out of the market entirely and the new trend of the repair community is broken 4K TVs. But I still got a working 8008S unit and with a large hardware trade in relatively close vicinity queued up, I bought a sparsely described 55″ on eBay. Pickup only, no photos, just a two-line description of the usual failure mode. Ten bucks. Fits nicely on the back seats of my Model S with the base removed. Anything larger will need to go into the trunk with seats folded down, but will then slide around and be a pain to move alone. So I’d say that’s my current sweetspot for a device that barely gets three hours of usage per month on average.

(moth and debris on the sofa not included)

For a quick comparison, here’s the back lids:
46″: One Ambilight module each side, two large ones across

55″: One per side (slightly larger) and three smaller units across

The connector panel is located at roughly the same distance from the edge, so it is clear that there needs to be a different PCB arrangement. Strangely, the 46″ has a symmetric placement:

while the 55″ has a centered power supply and the interface board moved over. I guess weight distribution doesn’t really matter at that size anymore and longer cables are more expensive, but wouldn’t it be better for heat distribution if those were apart quite a bit more? Oh, I forgot, all of those Philips TVs die from overheating as Philips doesn’t give a shit about what happens after the 2-year warranty expires… :evil:

Anyway, speakers seem to be the same which could be better on a larger TV. No other differences observed.
I then swapped the boards and all wiring matched up, no monkey business with different keys or flat flex widths, all working great. Small trap for inexperienced board swappers: For some reason the metal cover behind the horizontal ports needs to be swapped as well. These are not the same part, they differ in total height and their integration into the case. Failure to swap will create a bulging lid on the one TV and a noticeable gap on the other. Yes, the black styrofoam piece seems to be factory-installed. Yes, of course I only noticed after the large one was already mounted at the wall again and I just reassembled the smaller TV. Which I sold a week later locally for 20€, so pickup/shipping options, photos and a clear item description clearly make a difference.

For a quick test I fixed the lid with only a couple of screws, turned everything around, plugged in the AC cable and looked for an extension cord…and guess what, of course it fired right up! :yahoo:

That’s the hardware log in the service menu, accessible with the usual 062596i (info) combination. Same TV really, so the mainboard doesn’t care which size of patterned glass is attached.

Now there’s only one thing to resolve, and that’s the different Ambilight matrix. The 46″ uses a 9-18-9 LED assembly of four identical strips of nine RGB LEDs, which is a very nice optimization for lower cost production. The 55″ on the other hand uses a 10-22-10 matrix. That’s the polar opposite, as first of all 22 isn’t a multiple of 10, so they have to use at least one additional PCB layout, and second 22 doesn’t divide by the 3 panels that they’re using. So they decided to go for a 7-8-7 arrangement instead, which is crazy. Okay, at least the 8-wide part might be identical to the 40″ version as that one (as far as I can tell from images) uses a 8-16-8 matrix. Still, it wouldn’t have hurt to use 11-22-11 instead and make it go down a little closer to the speakers, right? Alright, whatever, you always need room for improvement, and people might upgrade from 3-sided “Ambilight XL” to, I don’t know, Ambilight Mega Super now-also-on-the-bottom XXL.

In practise, the mismatch of LEDs yields three non-lit pixels on the side strips, with the right one having dark pixels on the bottom and the left one on top. Which probably says something about the internal workings of the Ambilight alignment, but hey, I want that crap gone without reverse-engineering the damn firmware.

How is this set in software? I honestly still do not know. There’s no specific service menu option to actually set the numbers of LEDs on each side, so the next best thing is to set the option codes of the other model so that the mainboard now identifies as 55″ mainboard. Changing identity willy-nilly is a current megatrend, so we’ll do just that. It’s pretty easy since (I’m still fucking impressed) Philips does not hide these codes but instead prints them on the ID tag on the back of the lid…

46″ option codes:
50466 04771 61103 01220
63412 64946 09355 00000

55″ option codes:
50466 04774 61103 00964
63413 64946 09483 00000

No obvious location for the small pixel change here and much more numbers changed than strictly needed, so I’ll leave it at that – currently not worth the effort. With the changed code and a reboot, it’s now a 55PFL8008S device:

Note once again that if you do this conversion yourself, the 55″ TV needs a 400×400 VESA mount instead of the previous 200×200. I used the same screws, so case thickness should be roughly equal. It’s just that your wall mount needs to support the larger distance and also the slightly higher weight (~15kg); if using the regular base the latter also applies to your table. As mentioned, the first 46″ only got donated because it broke a glass table and got heavily scratched on the way down, so there’s that.

Celebrate with a quick 3 hour stream of Big Clive Live and you’re done!

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