Author Topic: EEVblog #725 - LG Plasma TV Teardown  (Read 24258 times)

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Offline EEVblog

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EEVblog #725 - LG Plasma TV Teardown
« on: March 18, 2015, 11:18:29 am »
Dave takes a peek inside the 50" LG Plasma TV found in the dumpster.
The Dumpster Dive video was on the EEVblog2 channel:

« Last Edit: March 18, 2015, 11:21:54 am by EEVblog »
 

Offline mux

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #1 on: March 18, 2015, 11:49:05 am »
I used to love these screens; the university once bought a whole bunch of them as display monitors, most of them died within one or two years and they would dump them en masse. They had incredibly many high quality and useful components in them. Those were also LG screens that used about 400W in normal operation!

Unfortunately, newer plasmas are considerably less valuable. Lots less power electronics and the electronics on there are less usable for parts. Screens still die after a laughably short amount of time and even though BOL image quality is undisputably great, after a while they all ghost and become very dim.
 

Offline mikeselectricstuff

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #2 on: March 18, 2015, 11:50:15 am »
I think that first "fuse" was a ferrite bead.

Would be interesting to see what's under the heatsinks on the HV driver boards.
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Offline bktemp

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #3 on: March 18, 2015, 12:06:05 pm »
Is it only the light beeing reflected or do those caps look bulged? There seems to be even some black stuff leaking at the top of each cap or are the caps deliberately beeing marked?
 

Offline Sionyn

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #4 on: March 18, 2015, 12:28:30 pm »
i checked out the smawha caps website their slogan is the challenge never ends... except for maybe making decent capacitors ?  :box:  :-DD
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Offline T3sl4co1l

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #5 on: March 18, 2015, 12:28:36 pm »
Not sure if that's black stuff oozing out, maybe more like the shadow inside the split.  They definitely look busted though.  Probable cause!

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Offline woox2k

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #6 on: March 18, 2015, 01:07:29 pm »
Is it only the light beeing reflected or do those caps look bulged? There seems to be even some black stuff leaking at the top of each cap or are the caps deliberately beeing marked?
Those are definitely bad caps even though the black stuff is just a marker. (quite common on those caps, probably marked after testing) I was screaming at my monitor when Dave was talking about the caps in the high-voltage supply and didn't notice the horde of bad caps in the logic power supply.
« Last Edit: March 18, 2015, 01:09:12 pm by woox2k »
 

Offline Rasz

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #7 on: March 18, 2015, 03:28:00 pm »
Is it only the light beeing reflected or do those caps look bulged? There seems to be even some black stuff leaking at the top of each cap or are the caps deliberately beeing marked?
Those are definitely bad caps even though the black stuff is just a marker. (quite common on those caps, probably marked after testing) I was screaming at my monitor when Dave was talking about the caps in the high-voltage supply and didn't notice the horde of bad caps in the logic power supply.

Dave subscribes to 'lets talk about it' school of repair videos.
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Online Fungus

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #8 on: March 18, 2015, 03:46:32 pm »
You mean the ones at 12:25 onward in the video?

How could Dave have missed those...?  :-//

 

Offline woox2k

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #9 on: March 18, 2015, 04:05:46 pm »
About the worth of repairing something. I can understand that the usage value is quite low on plasma screens these days but it's always worth to look into faults more closely and try to fix it. It's a EE channel afterall and repairing even the simplest things can teach a lot to people watching those videos. Like figuring out that bad caps can create weird lines and flicker on the screen like it is the case here probably. Even if the device is beyond economical repair Dave should look into it until he knows the source of the problem so other people might know what to look for in similar cases in the future.
Anyway, +1 to the videos where Dave actually tries to repair something.

It was just my opinion, i will not stop watching the videos either way.  :)
 

Offline ludek

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #10 on: March 18, 2015, 04:15:08 pm »
I think that Dave don't want to waste time, replacing caps... Just teardown. There's also only two film shots showing bad caps really clearly. And the other thing is it's weight - 50 kg...

Well, if I'd found a big plasma while dumpster diving - I could spend some time repairing this. :)


nice vid Dave btw.
« Last Edit: May 27, 2015, 12:53:22 am by ludek »
.
 

Offline SeanB

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #11 on: March 18, 2015, 04:38:35 pm »
5V, 3V3 and 12V rails off the LV section are all dead. There are about a dozen caps to change to get a nice 50 inch room heater. I went near one in a shop, and could both feel the heat radiating off the screen and feel my fillings buzzing from the RF energy.
 

Offline max666

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #12 on: March 18, 2015, 05:10:10 pm »
... I was screaming at my monitor when Dave was talking about the caps in the high-voltage supply and didn't notice the horde of bad caps in the logic power supply.

I think Dave does it on purpose ... checking if we pay attention  >:D
 

Offline Refrigerator

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #13 on: March 18, 2015, 05:12:57 pm »
Wait, you say these things fill the dumpsters ? where are those dumpsters ? i could definetly use some parts from those.  ::)
By the way i noticed you were whistling a different melody than usual.  :D
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Offline Spyke

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #14 on: March 18, 2015, 08:00:56 pm »
PDP's there would run at 50hertz vs 60 in north america/japan, etc. I don't know about anyone else but a 50hertz flicker is extremely irritating for me personally, its so bad that I could never watch TV over in Europe or the UK when tube tv's were the norm because of this. Thankfully LCD backlighting has eliminated that issue entirely.

I completely understand Dave's lack of motivation to repair this. He surely saw those caps but is playing a fast one on the rest of us to see if we noticed. Using a power hungry PDP in this day and age would be taking a huge step backwards, though one can argue about that if they still own a Kuro Elite, etc.
 

Offline DanielS

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #15 on: March 18, 2015, 08:55:09 pm »
5V, 3V3 and 12V rails off the LV section are all dead. There are about a dozen caps to change to get a nice 50 inch room heater.
The low-voltage caps powering the logic boards may explain the occasional video glitches but the flickering would have to come from the display panel circuitry and the HV caps appeared to be fine. I would have liked to see oscilloscope measurements of each rail to see how clean (or dirty) they were, see if any obvious suspect would have come up this way.
 

Offline herrmann

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #16 on: March 18, 2015, 08:57:28 pm »
Quote
I was screaming at my monitor when Dave was talking about the caps in the high-voltage supply and didn't notice the horde of bad caps in the logic power supply.

Me too, especially because you can recognize them immedeatly even from far look after the removing of the backplane. As a Professional he is, he should have mentioned them at least, unaware of the intention to repair it or not. :rant:

Just my 2 Cent

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Offline tom66

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #17 on: March 18, 2015, 09:37:08 pm »
The flicker is because it's a really cheap early LG plasma panel, FHD at that. So it's refreshing the panel at 360/480Hz per sustain or 6/8 subfields per main field. Pick up a late model 2013 Panasonic/Samsung/LG plasma and you won't get any flicker. Or a 9G Kuro. Flicker free.

Plasmas tend to last longer, mainly because the power electronics on an LCD are concentrated on the panel itself and these are thin ICs which dissipate watts a piece mounted right next to hot LED backlight bars.  Yeah, the power electronics can fail but so can the power electronics in LED- and CCFL-backlit LCD TVs. I've not noticed the power electronics being much less reliable but if something's gonna die on a plasma it'll be that.  At least you can repair the electronics if they do fail - you can't repair the LCD source drivers and it's a pain in the arse to replace the LEDs in backlit or edgelit screens, which seem to be failing quite a lot in Samsung and LG TVs.

Dave if you'd like to have fun with giving this panel a fitting funeral as it's already dead, take off the top and bottom long heatsinks and play a movie on the screen. After about 10 minutes the panel will slowly start frying itself and will fill itself with flickering colour lines and digital glitches. The TCP drivers dissipate a LOT of heat in the old panels (that thin daggy wiring is easily carrying 750mA@60V for the top & bottom, image dependent!) so they don't last long. The power consumption on Va is dependent on the image complexity - number of transitions per frame in vertical axis - rather than actual brightness. On a solid colour it can be under 20mA oddly enough. Makes for a difficult power supply design, must handle current swing from 20mA to 1.5A in one subfield (1/480Hz older panels, 1/1200Hz newer panels.) Hence the large amount of capacitance spread across the supply for Va to help with transient response.

BTW, it's incorrect to say Vs=Horizontal and Va=Vertical. The Vs is the SUSTAIN voltage (that's why it's called Vs) and powers the sustain drivers. Ultimately Vs actually makes the panel emit light. The Va is the ADDRESS voltage. That's what writes the data to panel itself, for display during a sustain field. The 570W figure is a purely theoretical figure that they have to put on for UL, which includes if the control board ISM mode is set to commercial display (ultra high bright.) Consumer 50" panels peak out at 400W from PSU  including Va and 450W from the mains. once you add in main board, audio, etc you're up to about 470-500W for a 2008 panel. 2013 panels from Panasonic got it below 200W peak and 125W average which is a pretty big leap, obviously still quite a lot but cool enough to run without fans.

And you'd have to pry my Kuro from my cold dead hands. I can't stand watching LCDs for anything with any dark content. Sure, they're better on brightness and power, but yuck. I justify the extra power usage as my dishwasher and fridge use more. Plasma gets <10hr/week use now.  It's reserved for movies and nature documentaries.
« Last Edit: March 18, 2015, 09:40:55 pm by tom66 »
 

Offline Grapsus

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #18 on: March 19, 2015, 01:02:11 am »
I once repaired a 50" LG plasma TV, it was an older model and had spurious horizontal lines. I was lucky to find a full service manual, it helped to narrow the problem down to Z sustain board (or maybe it was Y sustain). I got a replacement board for like $70.

I don't think those boards are repairable on component level. Since it's mainly a sort of a huge hybrid that is under those huge flat black heatsinks that contains many bare-die high voltage transistors bonded together on an aluminum plate. Unless of course you have crazy skills like Mike  :-/O

Sadly I found no service manual for 50PY3DF, but even with the manual you would have to find a 7 year old replacement board. So I totally agree that this TV is only good for salvaging parts.

About LG not using top brand caps, seeing how many they are and how big, I wonder how much it would cost to get equivalent Nippon Chemicon caps, probably more than the retail price of this TV...
 

Offline JoeN

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #19 on: March 19, 2015, 01:47:08 am »
I have a Panasonic Viera TH-42PZ85U 42-Inch plasma I got in June 2008 and it still works fine, but maybe I don't watch enough TV to cause reliability issues.   :-//

I think it's still better picture quality than almost all LCDs these days.  70.5 pounds, but it was lighter than the 35" CRT TV it replaced.

Apparently I paid $1300 for it.  TVs are cheaper now, but I don't think the quality is any better on 1080p models.

I'll replace it when I have to and probably not before.
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Offline RetroGameModz

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #20 on: March 19, 2015, 02:51:31 am »
Just as bktemp clearly pointed out in reply #4, and as other posters have also pointed out after that, those electrolytic capacitors on the power supply board have definitely gone bad and need to be replaced. I think that it's very likely that these caps are what's causing the problem, since insufficient smoothing of the supply voltages for the main board might affect the operation of that board. At least one of the supply voltages for the main board probably has a lot of ripple on it, which should be easy to see on a scope.
It becomes even more obvious when looking at the symptom at 18:49 in the video. A problem with either the Y sustain, Y buffer, Z sustain or X address board can cause a number of problems, but the symptoms usually then look completely different than what we saw here. Vertical or horizontal stationary or flickering lines or bars, horizontal lines flickering across the whole screen, dead portions of the image etc etc... The symptoms from those boards failing can be many, but what I saw in this video looked more like something being introduced already in the main board, which of course is due to the bad output caps for the main board in the power supply.
Looking at the statistics over common faults on plasma TVs (and CRT TVs too for that matter), the power supply output capacitors for the different power rails are the no 1 common issue when these devices fail. This is not strange considering these capacitors are operating in a very warm environment. The capacitors in this particular TV (as in many other plasma TVs) are sitting in the middle of two fat heat sinks as can easily be seen in the picture from reply #4, and warm ambient temperature does not go hand in hand with long operating life when it comes to e-caps, as we all know.

I really cannot understand how Dave could miss these bad capacitors. I noticed them pretty much instantly when the power supply shot started at around 5:52 into the video, and I was just waiting for him to spot them and mention something about them. Starting from 12:17, we are getting a close up of those caps and Dave is even waving around with his spudger over them, yet still misses to see them...?  :-//
Like someone else mentioned, I'm almost wondering if Dave did it on purpose just to check to see that we are awake and paying attention when watching his videos. :P

Also, I would like to mention something else about this particular episode.
I think Dave is awesome, and I have been giving Dave a thumbs up on every video he has released since about two years back now. But this is the first video that I felt that it didn't really deserve a thumbs up. (I never dislike videos, because that is extremely disrespectful towards the uploader - In this case, I just didn't click on thumbs up for the first time in more than two years.) The reason being that I felt that Dave's attitude towards the plasma TV in this episode was a bit disrespectful towards the hardware itself, so to speak. The attitude of "No one wants it, no one uses them anymore and they are nowadays nothing more than obsolete worthless piece of junk" does not comply with my own moral standards and values, and if that is what Dave really thinks, I can then not help but asking myself:

1. When Dave saw the plasma TV in the dumpster, why did he go through all the trouble of bringing the 50 kg beast into the lab? He obviously doesn't want it because he has no space for it and it consumes too much power, and he doesn't show much interest in repairing it either. So why did he take it then? It doesn't make any sense.

2. How does Dave know that "no one uses plasma TVs anymore"? Has he asked around to see what kind of TV technology different people all over the world are using these days? I for one prefer plasma TVs over any other kind of flat screen technology for a number of reasons, and I'm sure I'm not alone in this.

3. How come Dave doesn't mind salvaging parts from the TV and throwing the rest of it to the trash which will then eventually end up in the landfill (why not take mother nature into consideration for a change?), but he's unwilling to repair the TV even though replacing a few capacitors in the power supply will actually take a lot less time than it takes to salvage most of the boards (or at least some of them) for parts? I can understand that he doesn't want to keep the TV for himself due to the power consumption etc and that is fine, but why not fix it by replacing a few caps and then put it on eBay with a starting bid of a buck or so? Then it will end up in the hands of someone who actually appreciates it and can find some use for it. At the same time, Dave has earned a few bucks from selling the TV in a working condition. So in other words, it's a win-win situation. Now isn't that a lot better than having most of it going to the landfill?

I have noticed this disrespectful kind of attitude towards obsolete hardware in some of Dave's previous videos as well. I can also say for sure that I am definitely not the only one who has noticed this, because I have seen other people point this out in the YouTube comments for other videos, and it's easy to see that people are in agreement considering the number of thumbs up these kind of comments have gotten.
One of the better episodes I've seen lately is episode #722. It looks like Dave is in his best mood in that episode, and he delivers a cheerful presentation and has a very humble attitude towards both his viewers and the hardware that was inside his mail. But I must say that I was a bit disappointed when seeing this plasma TV episode because of Dave's seemingly unwillingness to even lift a finger to try to repair the TV, but instead planning on killing it completely by taking a few parts out and sending the rest right off to the landfill, just like that.  :'(
Come on, Dave. You could at least try to replace the caps and (if needed) do some basic troubleshooting like checking the voltages for ripple etc before binning the whole TV.

I think that the message Norcal715 delivers at the end of almost all of his videos is a very nice one: "With your help, we can keep these things out of the recycle bin and out of the landfill."

Dave if you'd like to have fun with giving this panel a fitting funeral as it's already dead....

Interesting post. However, the TV is not dead. Look at 18:49 in the video. There you can clearly see that the TV powers up and is even showing something on screen. That is not what most people would refer to as being "dead".
If you are referring to the plasma display panel itself... well, there is no evidence of the plasma panel in that TV being dead. On the contrary, it looks like there is nothing wrong with it at all.
The flickering shown at 18:49 could of course be caused by the camera as well, just as when filming CRT screens. But Dave did mention that the TV screen is flickering so this is not very likely to be a 'camera vs TV refresh rate'-kind of issue.
 

Offline calin

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #21 on: March 19, 2015, 02:56:55 am »
I have a Pioneer Elite - KURO PDP series series 60 inch i got in 2005 .. it was reeeeaaaallly expensive but the thing still works as it worked in day one and the image is something not too schmozze at. The LED TV I have (bigger and way cheaper than the Pioneer was) still does not have the same nice image and blacks that the plasma has. All in all I can say the Pioneer still stands after almost 10 years ... Heck I just looked on ebay the same odel still sels with soething between 2000 to 4000$ ... I did read some crap "specialist" review that this was the bentley of plasma TV's but really !!! still 4K .. yeah I paid more than 4K on it back in 05 :) 
« Last Edit: March 19, 2015, 02:59:02 am by calin »
 

Offline Tek_TDS220

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #22 on: March 19, 2015, 03:24:01 am »
I took a look at the Samwha website looking for a datasheet for their caps, but I couldn't find anything.  These things fail so regularly that I wonder if they have a guaranteed maximum lifetime?  Maybe they have a lifetime chart with time on one axis and temperature on the other.  Companies like LG and Samsung use these caps to ensure that the electronics they sell will only last a bit past the warranty period.
 

Offline JoeN

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #23 on: March 19, 2015, 03:43:19 am »
yeah I paid more than 4K on it back in 05 :)

Doesn't matter until there really is 4K.  4K monitors are one thing.  4K content is another.  I expect real general availability of 4K content is still 5 years away.  Who cares what the monitor can do until I can watch Raiders of the lost Ark on it :--.
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Offline RetroGameModz

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Re: EEVblog #725 - LG Plasma TV Teardown
« Reply #24 on: March 19, 2015, 03:45:08 am »
Companies like LG and Samsung use these caps to ensure that the electronics they sell will only last a bit past the warranty period.

I wouldn't be surprised if that is the case. Planned obsolescence; it's still happening today.
 


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