EEVblog #1154 - Surprising 4K Dumpster TV Fault - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: December 09, 2018, 01:40:06 am
content: A surprising fault in the 4K LG Dumpster TV.Using the block diagram and schematic to track down the likely culprit and reflowing the BGA's in an attempt to fix the fault.

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: December 09, 2018, 03:55:12 am
content: Great video, you should do more like this one.You should have just gave the television to Sagan so he could watch his dad's videos on Youtube or do school work using the browserTrying to Fix the television in my opinion is pretty much is a waste of time, if you are not going to swap out a replacement boardIt would have been nice if you put a link to the PDF file that contained the LG repair manual down in the description

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 09, 2018, 04:11:01 am
content: I'm surprised they went through the complication of having separate paths for the overlay and video. (Might have something to do with the 3D capability.) If I were designing a smart TV, I would just put in some sort of high performance processor with a good integrated GPU like a Ryzen APU, then use some dumb logic to connect that to the panel if a direct connection is not possible. Maybe also have a mux for a super low latency game mode and/or a discrete GPU in a high end model.

author: wilfred
author_rank: Super Contributor
timestamp: December 09, 2018, 04:18:53 am
content: Yeah, have another go. I'd like to see you try to reball that chip. At the very least it would show some of the pitfalls involved. I'm sure viewers would learn something even from a complete balls-up. (yes, shameful pun)

author: avetech
author_rank: Newbie
timestamp: December 09, 2018, 04:43:24 am
content: Just another case of built in obsolescence...End of an era repairing consumer electronics when cost of parts & labour are taken into consideration.

author: EEVblog
author_rank: Unknown
timestamp: December 09, 2018, 06:33:30 am
content: Quote from: johnlsenchak on December 09, 2018, 03:55:12 amVideo doesn't work, even from Youtube, I demonstrate this in the video.QuoteI can get a replacement board for $200

author: EEVblog
author_rank: Unknown
timestamp: December 09, 2018, 06:35:03 am
content: Quote from: wilfred on December 09, 2018, 04:18:53 amAnd a whole tone of hate mail if it doesn't work (more likley than not I figure)It's not like I have multiple chips and boards to practice with.For all I know the chip could be faulty.

author: tautech
author_rank: Super Contributor
timestamp: December 09, 2018, 07:00:17 am
content: Quote from: EEVblog on December 09, 2018, 06:33:30 amThat's not too bad.Quote from: EEVblog on December 09, 2018, 06:35:03 amStill, it would be a very interesting exercise to try and reball it, I'm sure we'll all learn something from your success or failure.A call for some advice before attempting it is gunna get you pointed in the right direction.

author: TheSteve
author_rank: Unknown
timestamp: December 09, 2018, 07:08:18 am
content: Service manual - nice!Reflow seemed reasonable - touching the chip always seems like a bad idea to me with so many fine pitch balls.What was "Surprising" about the fault though?

author: Rasz
author_rank: Super Contributor
timestamp: December 09, 2018, 08:10:27 am
content: Not the encoder. Encoder is there to facilitate recording from HDMI/Analog inputs to USB/cloud/buffering rewind feature/whatever smart TVs do. Maybe you meant Decoder, this one is used when playing streams/files/OTA TV. Also not the culprit - HDMI signal isnotencoded.The broken path is on the bottom, might be DE/BE blocks(probably not), might XD engine chip. Easiest way to check would be switching TV into "Game mode" - this disables all video processing and should just pass thru HDMI signal to the panel, except this is 120Hz panel so there is still forced frame doubling, and the fact you broke it completely in the mean timeGetting different result after second "just rehot cpu bro" was most likely due to the board cooling under XD Engine in the mean time, and nothing to do with second chip. Why no cold spray before grabbing hotair?even squeezing chips to the pcb with your finger and looking for difference on the screen would show soldering defects.btw you earnedhttps://www.designbyhumans.com/shop/mug/just-rehot-cpu-bro/947188/As other people already mentioned on YT it does look like typical ram problems, most likely XD engine ram used during video enhancement phase, OSD bypasses those and thats why it looked fine. OSD is also frame doubled to native 120Hz meaning turning TV into game mode would probably fix it, now we will never knowQuote from: johnlsenchak on December 09, 2018, 03:55:12 amhow do you know video was great if you didnt watch it? unless you want Sagan to look at pink horizontal lines all dayQuote from: NiHaoMike on December 09, 2018, 04:11:01 amhttps://en.wikipedia.org/wiki/XD_engineit does Video "enhancements", 60-to-120Hz fluidification, motion interpolation, de-blur, de-judder, color correction, dynamic color, dynamic contrast, smoothing, sharpening, removing details because case studies showed people will perceive distorted signal with higher brightest as better etc. You dont want those on your OSD, thats why there are two paths, OSD one bypasses all of this garbage.

author: woox2k
author_rank: Regular Contributor
timestamp: December 09, 2018, 11:30:54 am
content: Since HDMI was working fine i would have left it as is and used it as a monitor. Who cares about the smart-tv stuff anyway that gets out of date tomorrow forcing you to "buy" a new tv, remember this wasn't newest tv either.

author: coldmama9
author_rank: Newbie
timestamp: December 09, 2018, 11:45:28 am
content: Tried looking for a new chip... not sure if legithttps://www.aliexpress.com/item/LG1614-A1-2pcs-lot/32832288225.htmlhttps://www.aliexpress.com/item/LG1614-LG1614-A1-BGA-NEW-1PCS/32816344253.html

author: EEVblog
author_rank: Unknown
timestamp: December 09, 2018, 11:56:05 am
content: Quote from: TheSteve on December 09, 2018, 07:08:18 amIf I said to you that a TV displayed everything fine, except for playing back video, including inside Netflix and Youtube, that wouldn't be a surprising fault to you?

author: EEVblog
author_rank: Unknown
timestamp: December 09, 2018, 11:56:59 am
content: Quote from: woox2k on December 09, 2018, 11:30:54 amHDMI was not working fine, see my first video.No video from any source, either input or streamed or recorded played back.

author: EEVblog
author_rank: Unknown
timestamp: December 09, 2018, 12:01:45 pm
content: Quote from: Rasz on December 09, 2018, 08:10:27 amNope, it was the second U14 chip. Fault was entirely consistent, you didn't see all the stuff off-camera.QuoteI forgot, have done that in other TV videos. Everyone was so keen to see the chips reflowed.QuoteGreat theory, but doesn't explain the big and permanent change when U14 was reflowed.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 09, 2018, 01:45:47 pm
content: Quote from: Rasz on December 09, 2018, 08:10:27 amThat's something a GPU can do, although I suppose a TFLOPS class GPU was way more expensive back then. Nowadays, a Ryzen APU is available up to 1.8TFLOPS.Now I wonder if there's some universal DP input board available that can output the exact signal the panel expects, in order to turn the TV into a 4K 120Hz gaming display.

author: woox2k
author_rank: Regular Contributor
timestamp: December 09, 2018, 03:16:37 pm
content: Quote from: EEVblog on December 09, 2018, 11:56:59 amRight, totally forgot all about that. Would have been great if you had thought about turning the "Game" mode on that bypasses the cpu entirely to narrow down the faulty area. Then again not all TV's even have that feature and it became clear only after looking at the block diagram...

author: Vcj
author_rank: Newbie
timestamp: December 09, 2018, 03:54:14 pm
content: Quote from: johnlsenchak on December 09, 2018, 03:55:12 amWhere are download this PDF? Very interesting book for me

author: Rasz
author_rank: Super Contributor
timestamp: December 09, 2018, 09:35:07 pm
content: Quote from: EEVblog on December 09, 2018, 12:01:45 pmthen it has to be U14 ram, I looked into my stash of service manuals (there was actually a magazine in Poland dedicated to people servicing electronics, ran all the way to 2016http://w.serwis-elektroniki.com.pl/spistr.html) and everywhere LG1614 is paired with URSA9 and both are equally called visual processors. Looks like what LG marketing calls "XD engine" consist of both of those chips.I cant blame you for fat fingering the chip, I probably screwed ~20 bga jobs, while learning on old graphic cards/laptops, before getting the hang of it.

author: BrianHG
author_rank: Super Contributor
timestamp: December 09, 2018, 11:55:30 pm
content: @dave, nothing wrong with everything you did, however, I was surprised that with the TV powered up, before bringing out the hot air, after identifying the possible bad chips, that you didn't try pressing down on each IC with your thumb as a trial just to see if there was a difference.I've found bad balls that way, sometime not on the main IC, but a ram chip right next to them, or even which quadrant on the IC where the cold joint is located.

author: Kilrah
author_rank: Unknown
timestamp: December 10, 2018, 11:49:58 am
content: I would have concentrated on RAM chips before starting to fiddle with the large fine BGAs, just as likely if not more that one of them was the issue.

author: glarsson
author_rank: Frequent Contributor
timestamp: December 10, 2018, 12:28:32 pm
content: Quote from: EEVblog on December 09, 2018, 12:01:45 pmHeating up the big chip and poking it would certainly explain a big and permanent change. The original fault might still be present, e.g around the RAM chips, but is now no longer visible.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 10, 2018, 05:06:32 pm
content: Quote from: EEVblog on December 09, 2018, 06:35:03 amBGA reballing seems to be the electronics-nerd version of watching football. People get equally emotional about it and there´s thousands of coaches as well.I would like to watch a try... otoh i watched Louis Rossmann do it occasionally (often enough to know i am not equipped and not skilled for that). Such a video would mean a lot of effort without guarantee of success, though. Getting it to run with the 200$ replacement part would still be a success. Even a practical approach to the process of repairing and selling these items would be interesting to watch.

author: MT
author_rank: Super Contributor
timestamp: December 10, 2018, 06:07:51 pm
content: Gonski!

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: December 11, 2018, 08:18:21 pm
content: Quote from: EEVblog on December 09, 2018, 06:35:03 amThere's that YouTube channel Strange Parts where a guy goes through perdition and back learning how to reball microchips. And thats with the correct stencils. Good luck finding a stencil for this board. Really... I think just get a replacement board and call it done. But nice work tracing the fault down, that's the most important thing to me.

author: Rasz
author_rank: Super Contributor
timestamp: December 11, 2018, 09:19:54 pm
content: Quote from: Wan Huang Luo on December 11, 2018, 08:18:21 pmchip. Stencils are bga package specific, and mostly standardizedQuote from: Wan Huang Luo on December 11, 2018, 08:18:21 pmdid he tho?

author: EEVblog
author_rank: Unknown
timestamp: December 17, 2018, 02:12:14 am
content: UPDATE:A cheap board swap worked (obviously)

author: EEVblog
author_rank: Unknown
timestamp: December 17, 2018, 02:18:49 am
content: Quote from: SparkyFX on December 10, 2018, 05:06:32 pmThat's the thing, the odds of a re-balling working would not be high. I have to look at where I stand. A chip that has been reheated half a dozen times, no idea if it still work, no idea if pads will lift when taking it off, no idea if the reballing will work (with zero experience doing this, and zero practice because it's a one-shot deal), Very difficult to troubleshoot if it goes wrong, and no idea if there is not another fault on top of that. Add all that up, and the fact that if I don't fix it and get it working the hate mail will be enormous. Guess my enthusiasm level for doing that video....

author: cdev
author_rank: Super Contributor
timestamp: December 17, 2018, 02:21:04 am
content: great!many of these TVs run Linux, so there may be logs.The 2:1 mux etc seems to me likely to be the stereo- one screen but two frame buffers and a means of switching between them so you get one channel for each eye's signal You likely have to wear LCD shutter glasses or something like that to watch it.

author: Titter
author_rank: Newbie
timestamp: December 17, 2018, 02:28:36 am
content: https://www.eevblog.com/forum/blog/eevblog-1154-surprising-4k-dumpster-tv-fault/msg2028256/#msg2028256This is exactly the right answer.

author: Titter
author_rank: Newbie
timestamp: December 17, 2018, 02:35:09 am
content: Reflow those RAM chips, just for S & Giggles

author: EEVblog
author_rank: Unknown
timestamp: December 17, 2018, 09:53:12 am
content: Quote from: Titter on December 17, 2018, 02:35:09 amFat lot of good that does unless the mains chip works again.

author: boffin
author_rank: Unknown
timestamp: December 17, 2018, 04:15:58 pm
content: Quote from: EEVblog on December 17, 2018, 02:12:14 amHow cheap? and where from ?

author: cdev
author_rank: Super Contributor
timestamp: December 17, 2018, 05:19:02 pm
content: Dave, if I were you, unless its been fixed now, I would leave it alone if you can use it as a nice 4K monitor without the internet enabled on the fly video decompression features.You can add a cheap media box to handle that.But of course, I am not you, and - itdoesmake a very interesting story and videos.

author: Kilrah
author_rank: Unknown
timestamp: December 17, 2018, 09:45:37 pm
content: It did NOT work as a monitor as Dave mentioned several times, image was crippled also on HDMI inputs.

author: thm_w
author_rank: Super Contributor
timestamp: December 17, 2018, 10:56:39 pm
content: Quote from: Kilrah on December 17, 2018, 09:45:37 pmbut its fixed now... so...

author: Rasz
author_rank: Super Contributor
timestamp: December 18, 2018, 03:45:41 am
content: Quote from: thm_w on December 17, 2018, 10:56:39 pmbut it didnt, and cdev obviously didnt watch the video... so...