Author Topic: EEVblog #1154 - Surprising 4K Dumpster TV Fault  (Read 3499 times)

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Offline EEVblog

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EEVblog #1154 - Surprising 4K Dumpster TV Fault
« on: December 09, 2018, 12:40:06 pm »
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.

 

Offline johnlsenchak

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #1 on: December 09, 2018, 02:55:12 pm »


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 browser

Trying  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  board

It  would have been   nice if you put a link to  the PDF  file that contained the LG repair manual  down in the description
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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #2 on: December 09, 2018, 03:11:01 pm »
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.
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Online wilfred

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #3 on: December 09, 2018, 03:18:53 pm »
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)
 

Offline avetech

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #4 on: December 09, 2018, 03:43:24 pm »
Just another case of built in obsolescence...
End of an era repairing consumer electronics when cost of parts & labour are taken into consideration.
 :(
 

Offline EEVblog

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #5 on: December 09, 2018, 05:33:30 pm »
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 browser

Video doesn't work, even from Youtube, I demonstrate this in the video.

Quote
Trying  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  board

I can get a replacement board for $200
 

Offline EEVblog

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #6 on: December 09, 2018, 05:35:03 pm »
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)

And 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.
 

Offline tautech

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #7 on: December 09, 2018, 06:00:17 pm »
I can get a replacement board for $200
That's not too bad.

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)
And 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.
Still, 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.


 ;D
« Last Edit: December 09, 2018, 06:23:36 pm by tautech »
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Online TheSteve

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #8 on: December 09, 2018, 06:08:18 pm »
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?
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Offline Rasz

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #9 on: December 09, 2018, 07:10:27 pm »
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 is not encoded.

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 time :P

Getting 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 earned https://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 know :P


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 browser

how do you know video was great if you didnt watch it? unless you want Sagan to look at pink horizontal lines all day

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.)

https://en.wikipedia.org/wiki/XD_engine
it 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.

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Offline woox2k

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #10 on: December 09, 2018, 10:30:54 pm »
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.
 

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Offline EEVblog

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #12 on: December 09, 2018, 10:56:05 pm »
What was "Surprising" about the fault though?

If 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?
 

Offline EEVblog

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #13 on: December 09, 2018, 10:56:59 pm »
Since HDMI was working fine

HDMI was not working fine, see my first video.
No video from any source, either input or streamed or recorded played back.
 

Offline EEVblog

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #14 on: December 09, 2018, 11:01:45 pm »
Getting 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.

Nope, it was the second U14 chip. Fault was entirely consistent, you didn't see all the stuff off-camera.

Quote
Why no cold spray before grabbing hotair?

I forgot, have done that in other TV videos. Everyone was so keen to see the chips reflowed.

Quote
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.

Great theory, but doesn't explain the big and permanent change when U14 was reflowed.
 

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #15 on: December 10, 2018, 12:45:47 am »
it 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.
That'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.
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Offline woox2k

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #16 on: December 10, 2018, 02:16:37 am »
HDMI was not working fine, see my first video.
No video from any source, either input or streamed or recorded played back.
Right, 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...
 

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #17 on: December 10, 2018, 02:54:14 am »
It  would have been   nice if you put a link to  the PDF  file that contained the LG repair manual  down in the description

Where are download this PDF?  Very interesting book for me
 

Offline Rasz

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #18 on: December 10, 2018, 08:35:07 am »
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.

Great theory, but doesn't explain the big and permanent change when U14 was reflowed.

then 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 2016 http://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.
« Last Edit: December 10, 2018, 08:48:57 am by Rasz »
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Offline BrianHG

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #19 on: December 10, 2018, 10:55:30 am »
@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.

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Offline Kilrah

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #20 on: December 10, 2018, 10:49:58 pm »
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.
 
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Offline glarsson

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #21 on: December 10, 2018, 11:28:32 pm »
Great theory, but doesn't explain the big and permanent change when U14 was reflowed.
Heating 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.
 
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Offline SparkyFX

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #22 on: December 11, 2018, 04:06:32 am »
And a whole tone of hate mail if it doesn't work (more likley than not I figure)
BGA 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.  :-DD

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.
 

Offline MT

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #23 on: December 11, 2018, 05:07:51 am »
Gonski! :-BROKE
 

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Re: EEVblog #1154 - Surprising 4K Dumpster TV Fault
« Reply #24 on: December 12, 2018, 07:18:21 am »
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)

And 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.
There'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.
 


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