EEVblog #780 - Samsung LCD TV Dumpster Dive Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: August 17, 2015, 09:59:56 pm
content: Dave finds a nice 46" Samsung LED backlight LCD TV in the dumpster, will it work?What's inside?Also I look at using the Inventables waterproof insulating solder sleeves:https://www.inventables.com/technologies/solder-sleeves

author: eV1Te
author_rank: Regular Contributor
timestamp: August 17, 2015, 10:22:41 pm
content: I think you made one of the biggest rookie soldering mistake in this video.I am talking about the Inventables solder sleeves where you put all the heat into the solder and not the copper! With your thin and focused heat gun nozzle the copper wires were still stone cold when the solder melted, thus the solder never wetted the copper. With a typical hand held heat gun you would heat the entire cable and solder at the same time... however depending on the cable you use you might melt the insulation as well I guess...

author: EEVblog
author_rank: Unknown
timestamp: August 17, 2015, 10:48:54 pm
content: Quote from: eV1Te on August 17, 2015, 10:22:41 pmSure you could blast the whole thing with a huge wide nozzle heat gun, but as you said, wire insulation would likely melt.My nozzle was small, but I thought should have been big enough to do the job, I was trying to heat the wires as well.But yeah, bigger nozzle next time.

author: HighTower
author_rank: Newbie
timestamp: August 17, 2015, 11:09:25 pm
content: I think this LCD is beyond economical repaire. You can buy a T-con, but of course you can't be sure that that is the problem. I had the same problem, had a number of LCD-s half working, and didn't know what to do with them. Instead of throwing them out, you should take off the LCD panel itself, revealing the backlight, and than wire the psu so that it powers up from suspend, and lights up the backlight. Usually, as I found, the power up for the psu is one line, a logic high/low, so as the backlight. And on most of the panels there is a brightness control. Now this one varies. Sometimes its just a voltage for 0 to 3.3/5 volts, controlling the brightness linearly, and sometimes it needs a pwm signal, to do the adjusting, so by just wiring it high, sould make it blast at its full brightness. It's pretty cool actually, I threw 3 of these above my desk and they seem to be very bright but not unpleasant to look at because the light is so dissipated. I think it would make a good video.Keep up, nice videos - a regular follower of the blog, and an electrical engineering student.

author: Roughrider
author_rank: Newbie
timestamp: August 18, 2015, 12:23:52 am
content: We used to use these in the military for quick wire repairs... we used a small heat gun but the key is to use a round deflector for heating the crimp evenly on all sides. They are a bit of a challenge, but they do work well. Also as a side note I may be able to get you the service/parts manual for this tv, I'll have a look tomorrow and see if I can get this for you.

author: EEgalitarian512
author_rank: Contributor
timestamp: August 18, 2015, 01:30:00 am
content: Hi Dave. You probably already got this idea. I Googled your brand/model and came up with:http://www.samsung.com/au/support/model/UA46B7100WFXXY.This looks like Samsung Australia. They do have live chat - no guarantees, of course. You can also get a live phone conversation at shopjimmy.com. They specialize in supplying parts and support for LCD TVs. John

author: Rasz
author_rank: Super Contributor
timestamp: August 18, 2015, 03:03:22 am
content: vented/bulged caps are bad, non vented/non bulged caps are NOT automagically ok. post hoc ergo propter hocsmps can work above 100KHz, better to check using oscilloscope or measure cap esr directly, not everyone has a $400 meter with enough bandwidthmemory after effect suggests tcon, something with bias voltage (maybe two chips in upper left corner of tcon are bias drivers?) or broken connection

author: Porto
author_rank: Contributor
timestamp: August 18, 2015, 03:48:13 am
content: Well, that LCD screen works alot better than the 23" Apple Cinema Display I have here...http://youtu.be/_JxAz1g_bZ0Cool thing is, it kinda looks like an animated background where the Earth is nuked....

author: ijchan223
author_rank: Contributor
timestamp: August 18, 2015, 03:57:10 am
content: to me it looks like a bad edge connector on the panel. to verify this you can take the panel out and run your hand across the connector and see if there is any change if it does become good you can wedge something between the metal frame and the panel. its not the proper fix but it can last for a bit.

author: djQUAN
author_rank: Frequent Contributor
timestamp: August 18, 2015, 04:24:11 am
content: We also had a Samsung LCD TV fail recently. Ours was different though. The power supply failed.No bulging caps or any blown parts. It just died. I checked and the standby 5V power supply died and killed the rest. I didn't bother trying to order stuff and try to fix it. Just sent it to the service center where they will probably just swap the boards.It was interesting though when I also saw the low profile construction. Everything was done to minimize height. I'll try to get pics when we get it back.

author: Tothwolf
author_rank: Regular Contributor
timestamp: August 18, 2015, 06:04:41 am
content: At first I was thinking "Oh no, not another television", however the way Samsung built it to reduce the overall depth is quite interesting. I'd assume the low profile design is also why it does not have an IEC 320 C14 inlet connector for a power cord.I've seen this failure mode before with smaller LCD displays and with those, the failure was of the bond between the flat flex cables and LCD panel itself. At the time I investigated what it would take to repair the connections, but ultimately I just replaced the LCD assemblies.One minor clarification, those black SMD capacitors on the driver board are not the traditional solid tantalum MnO2 (manganese dioxide) types [aka flaming capacitors of death] we are all so familiar with, but rather a tantalum polymer type.123...no more burning tantalum capacitors and charred boards

author: Tothwolf
author_rank: Regular Contributor
timestamp: August 18, 2015, 06:27:30 am
content: Quote from: Rasz on August 18, 2015, 03:03:22 am^^^^^^^^^^This.Back in the days of the capacitor plague induced mass-failures of PC motherboards, the low-ESR capacitors on FIC branded motherboards (and OEM motherboards manufactured by FIC for Compaq and others) did not swell and burst their tops. They did however increase in ESR which would cause system instability. FIC was pretty good about swapping out or repairing their own FIC branded boards, while OEMs like Compaq were not so easy to deal with since most systems that seemed to be failing were just outside of their original warranty.

author: Refrigerator
author_rank: Super Contributor
timestamp: August 18, 2015, 07:09:43 am
content: Dave, I don't know if you've seen this comment on your video but this guy seems to know what's going on and there's alot of people who agree with him, here's the comment.Quote from: Richard Smith (from YT comments)

author: redshift
author_rank: Contributor
timestamp: August 18, 2015, 07:26:18 am
content: I'm not qualified at all to give advice but I once had an almost identical fault on a 26" NTSC Samsung LCD.But in my case the problem was intermittent. This was useful because while it was working I could have it open, spray around with microfreeze spray and see what reproduced the fault(cold solder joint(s)?). Sure enough it was the T-Con board and after attempting to reflow to no avail, I was able to find a replacement board on ebay for $15. And that worked perfectly!Perhaps try heating it or letting it run a long time to see if the fault temporarily goes away.

author: EEVblog
author_rank: Unknown
timestamp: August 18, 2015, 07:27:37 am
content: Quote from: Refrigerator on August 18, 2015, 07:09:43 amNope, tried that.

author: EEVblog
author_rank: Unknown
timestamp: August 18, 2015, 07:28:42 am
content: Quote from: Rasz on August 18, 2015, 03:03:22 amThat's why I've used an ESR meter on them. Seems ok.

author: redshift
author_rank: Contributor
timestamp: August 18, 2015, 07:50:01 am
content: Quote from: Rasz on August 18, 2015, 03:03:22 amAnd I hate to be that guy but I believe the logical fallacy here is "Denying the Antecedent". Could be wrong though.But the insight that the SMPS might be above an ESR meter's 100kHz signal is interesting. Do you think the effect of testing capacitors in circuit or the ESR meters' bandwidth would begin to skew measured ESR faster in these sort of circuits?

author: bktemp
author_rank: Super Contributor
timestamp: August 18, 2015, 07:56:52 am
content: It is most likely the TCON board. Or more precisely the VCOM/GAMMA buffer. If one of the analogue voltages going into the panel is missing or wrong it will result in wrong coolurs and image sticking. You can clearly see it at the end when them image gets worse over time.

author: vlad777
author_rank: Frequent Contributor
timestamp: August 18, 2015, 11:58:45 am
content: If this was a graphics card than the fault would obviously be memory.What is that memory doing on the TCON board ? Is it maybe a frame buffer?

author: bktemp
author_rank: Super Contributor
timestamp: August 18, 2015, 12:29:27 pm
content: Quote from: vlad777 on August 18, 2015, 11:58:45 amOlder TFTs do not have memory, because the TCON does only what its name suggests: It generates timing signals for the TFT panel.It would be interesting if anybody knows what kind of processing is done on modern TCON boards because I have seen this several times but could not find any information about it.My guess is, the framerate is doubled or quadrupled. Most modern TFT panels used in TVs run at 100/120 or 200/240Hz instead of the common 50/60Hz. 1920x1080 @ 60Hz uses 145MHz pixel clock. The connection to the main processor board does not look like it can handle 580MHz pixel clock ( = 14GBit/s!). Therefore it makes sense to increase the framerate directly at the TFT panel.@DaveIf you want to give it a try repairing the TCON board, look at the ics marked on the picture. It is hard to tell without knowing the part numbers, but my guess is one of those ics is the gamma buffer. They are used to generate the voltages needed by the panel to generate the individual colours. Because LCDs don't like DC, all voltages are symmetrical to the VCOM reference voltage. If one voltage fails, the display sees a DC voltage instead of the AC signal and this produces all kind of weird effects. Those horizontal lines you have seen are typical for a problem with the row inversion.Because the gamma buffers have to drive the capacitive load of the whole TFT LCD panel, they run hot and fail quite often in large LCD TV.The +15V you have measured is the analogue supply voltage for the TFT panel.

author: VK3DRB
author_rank: Super Contributor
timestamp: August 18, 2015, 12:46:07 pm
content: You had the right approach... thermal, checking the obvious etc.Next trick... get hold the full service manual which should include schematic diagrams and even waveforms or at least DC voltage levels. Then you should be able to debug it to chip level.http://www.s-manuals.com/tv/samsunghttp://www.eserviceinfo.com/equipment_mfg/Samsung_2.htmland plenty of other websites.

author: spackard
author_rank: Newbie
timestamp: August 18, 2015, 12:47:24 pm
content: Try squeezing or pinching the bottom of the screen (where the black plastic is). I bought my dad a Samsung 50" a few years ago, it started having one vertical line, and pinching it made the line disappear. Of course, you have an advanced case of vertical lines.BTW, I think the problem is mechanical; you're tackling it as if it's electronic.

author: ehoffman
author_rank: Newbie
timestamp: August 18, 2015, 05:19:39 pm
content: Hello DaveWhen you turned on the TV, there was no visible problem for a few seconds, and then it appeared. This make me think it could indeed be heat-related. It really look like a frame buffer issue (memory or video processor). You had a good idea with the freeze-it, but when you tried, you had a static image displayed. If the processor doesn't update the video memory while you freeze the board, then the "corruption" may just be left intact in the memory. If the data doesn't get to the memory right, it would explain the corruption. Also, noticing one line out of 2 being bad on the display, and also noticing that there is 2 memory chips, one of the 2 chips could be "bad".I would suggest doing the freeze-it again while displaying a dynamic image, like the screensaver or a live feed.It could just be a simple thing as the memory chips not being heat-coupled to the back panel cover (missing or not-touching thermal pad for example, after all, proof being the stripped screw, it seem that the cover had been opened before).Just an hypothesis...Regards,Eric

author: edy
author_rank: Super Contributor
timestamp: August 18, 2015, 05:42:09 pm
content: Oh no.... Not another Samsung....This one's from a few years back but shows a common mode of failure (lasted ~2 years) that I'm sure scrapped a huge number of TV's and led to one big Class Action lawsuit that Samsung settled in the USA:And then here is a video thanking Dave and EEVBlog for helping me fix my Philips TV (lasted ~1 year before I had to order a set of parts from ShopJimmy.com):I wish I had a dumpster like Dave! I'd never have to buy any TV's!

author: free_electron
author_rank: Super Contributor
timestamp: August 18, 2015, 05:57:32 pm
content: those solder sleeves have been around for a long time.invented by AMP ( Tyco )http://www.digikey.com/catalog/en/search?filters=18111

author: German_EE
author_rank: Super Contributor
timestamp: August 18, 2015, 06:31:38 pm
content: Some of the techniques used to achieve a low profile were interesting, especially the daughter boards used for the relays. Some of those manufactured with space for a SMD back EMF diode would be a useful space filler on a China manufactured PCB

author: Frost
author_rank: Regular Contributor
timestamp: August 18, 2015, 06:38:47 pm
content: Quote from: free_electron on August 18, 2015, 05:57:32 pmYes, but what's their advantage?I normally use crimp butt connectors of the CrimpSeal II seriesfrom DSG-Canusa, this are ordinary crimp connectorswith a shrink tube and an inner adhesive layer whichmelts during the shrink process.They work very well, are 100% watertight after shrinkingand very easy to use.

author: Dino KL0S
author_rank: Contributor
timestamp: August 18, 2015, 06:51:15 pm
content: I was curious about Dave's problem having the solder flow in those solder sleeves since they looked like an interesting thing to have around. I e-mailed customer service at Inventables and here's what they replied...hmmm, wonder if anyone has actually had good luck with them?Subject: Solder SleevesAUG 18, 2015 | 01:42PM CDTSam replied:Hi,We do not actually have the melting point for this item, but it should be the same as plain solders 183 °C. We sell a heat gun that works really well with them:https://www.inventables.com/technologies/heat-gunSamantha Jo AlaimoCustomer Success SpecialistInventablesAUG 17, 2015 | 06:55PM CDTOriginal messageDino wrote:What temperature is required to activate the solder in the sleeves? I was very interested in these but in a recent EEVBlog episode Dave Jones had difficulty heating the joint to a point where the solder would melt and flow. Your product video example shows a large heat source and very quick melt, albeit with a smaller wire gauge and sleeve size. Thanks in advance!

author: edy
author_rank: Super Contributor
timestamp: August 18, 2015, 08:25:19 pm
content: Quote from: EEVblog on August 17, 2015, 10:48:54 pmI wonder if it would help to dip the 2 wire ends into some rosin flux and get them all loaded up before sticking them into the Shrink-Wrap-Solder tube? Then you would see your flux getting all bubbly and melting away on the copper. It might look like a mess, but perhaps would improve solder flow?

author: max_torque
author_rank: Super Contributor
timestamp: August 18, 2015, 09:26:26 pm
content: Quote from: Frost on August 18, 2015, 06:38:47 pmI have no idea why you would want to solder a splice, when you could crimp it?Just get the normal AMP/Tyco adhesive sealing crimps you mention...(solder is a really bad way to join wires, especially unsupported wires subject to ANY vibration or bending, as solder wicks up wire, leaving a rigid section, at which point any vibrations are concentrated and cause a failure. Not for nothing does the space,aero and automotive industry crimp EVERYTHING)

author: artag
author_rank: Super Contributor
timestamp: August 18, 2015, 09:32:38 pm
content: Quote from: free_electron on August 18, 2015, 05:57:32 pmInvented by Raychem, I think. These might be clones. They're cheaper than the Raychem ones.http://www.farnell.com/datasheets/1680945.pdfTyco, AMP and Raychem are all owned by TE Connectivity now, though.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 18, 2015, 09:48:54 pm
content: Lcd had a lot of quality problems before, the lcd controllers matrix inside the lcd panel had bad contacts, they were glued/tacked on pcbs and had poor contacts.I founded a very beautiful 46" lcd tv who had half the vertical display working, very good at cold but problems when hot.Google search told me a lot of lcd failures had that problem, i cant recall the lcd panel maker.

author: zze110
author_rank: Contributor
timestamp: August 19, 2015, 12:35:36 am
content: Here's how to get the TV in to test pattern modeTV in standby mode. Press Mute 1 8 2 Then power On... should put you in service mode.Select "svc/service/control" , "test mode or test pattern", "FRC pattern"Pattern in generated from T-CON board directly.The tv may have a hidden menu also. Try 0 2 1 4 exit if neededIn the documentation I found... "vertical or horizontal lines: defective panel likely but also t-con, lvds, or mainboard. Use test patterns in factory service mode to determine error."When done, press power button to save settings.

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 19, 2015, 08:52:58 am
content: Quote from: zze110 on August 19, 2015, 12:35:36 amYou need the remote for that...

author: edy
author_rank: Super Contributor
timestamp: August 19, 2015, 11:01:31 am
content: A cheap universal remote should do the trick. Handy to have around and reprogram to use for any dumpster dives missing the original remote. Hopefully these newer TV models and old ones are all supported. Most should have a long list of models/makes they are compatible with and should allow direct programming to the TV you want.

author: TheAmmoniacal
author_rank: Unknown
timestamp: August 19, 2015, 11:17:24 am
content: Did you catch this video?In brief: If you enter the service menu, and click through to set the sub contrast down, it pretty much removes the lines: ADC/WB -> White Balance -> Sub Contrast: 70It seems like you need the remote to enter the service menu, maybe you can find a way to enter that menu with the capacitive buttons? (don't know the model so I can't check the user manual)

author: rollatorwieltje
author_rank: Unknown
timestamp: August 19, 2015, 11:29:16 am
content: If you have a phone or tablet with IR port there are several apps that can mimic actual remotes.For Samsung there's also Samygo Remote, it uses wifi or ethernet.

author: bktemp
author_rank: Super Contributor
timestamp: August 19, 2015, 11:29:47 am
content: After seeing the second video, it is clearly a faulty gamma buffer or some other analogue voltage driving the panel:You only see the vertical lines on bright colours, because only then the voltage from the faulty gamma buffer channel is used.The stripes get worse over time because a DC offset build up in the panel and saturates the pixels.

author: davidmc
author_rank: Newbie
timestamp: August 19, 2015, 11:51:41 am
content: Just an idea from watching the video, and I cant see pixels clearly enough to check this in the video, but is it possible the issue is actually in the horizontal line drive, with the vertical bars then resulting from the problem rows 'averaging' the signal that they see with their selects floating or similar.If it were the left side horizontal drive (right when upside down), this would be consistent also with the behaviour where connecting the right side of the screen produced half a menu while connecting just the left didn't. Pne way it still has the good row signals, bad ones discconected, while the other way the only connected rows are the bad ones.

author: Kerden
author_rank: Newbie
timestamp: August 19, 2015, 01:51:42 pm
content: Quote from: davidmc on August 19, 2015, 11:51:41 amI'll second that!It should be fairly easy to test: If this is true, the vertical lines will only show in the rows which do not display the correct video signal. so the "striped-rows" pattern should be inverted.As davidmc said, this would mean that the rows are floating and will build up charge, until the voltage difference is enough to switch on the pixels. This would also explain why the vertical bars match the colour of the displayed signal.

author: Rasz
author_rank: Super Contributor
timestamp: August 19, 2015, 04:09:09 pm
content: Quote from: TheAmmoniacal on August 19, 2015, 11:17:24 amnice find man! this and same effect even with only one flex connected confirms dc bias on the tcon board as the culprit

author: TeaNTronics
author_rank: Contributor
timestamp: August 19, 2015, 05:40:25 pm
content: Quote from: Dino KL0S on August 18, 2015, 06:51:15 pmno wonder it didn't worked well for dave,in their website, they say it got 2 temperature settings:750 °F (398.89 °C) and 1000°F (537.78 °C)it's not a low melting point solder after allp.s. it's looks like paint removing heat gun that you can get in hardware store

author: Protonus
author_rank: Newbie
timestamp: August 19, 2015, 06:41:57 pm
content: Dave - check those Sam Young filter caps on the power supply board using your ESR meter! I don't see that you did that in either video? I know you have no reason to think they're bad based on ripple and visual diagnosis. BUT - I have a very similar vintage Samsung LCD TV (2009, 55", high end) I'm working on, that also has multiple Sam Young filter caps on a very similar board. One of them was visibly bulged, but even the ones that weren't in the same value (25V 1000uF) had questionable/high ESR values.It has the exact same symptoms yours does.I'm waiting for the replacement caps to arrive, but given the nature of the failure (it worsened with time according to the owner, used to go away on it's own, and it's temperature related) etc, and the fact that one had visibly failed - I'm confident that this is what's wrong.

author: Rasz
author_rank: Super Contributor
timestamp: August 19, 2015, 07:13:11 pm
content: Quote from: Protonus on August 19, 2015, 06:41:57 pmits not, in this particular case its not the electrolytic caps for a change

author: Godzil
author_rank: Frequent Contributor
timestamp: August 19, 2015, 07:33:57 pm
content: Dave: could you do some close-up picture on the bar on the screen?I wonder if some of the "magic" filter that TV manufacturer tends to put are not what started to failed.The other possibility is as the video processor is likely to handle different alpha blended framebuffer, the one used to display text (which could be different from the one used for the boxe) have some problem.It's unlikely to be a software problem, but who knows, that's true it's strange that it only happen on the text shapes.

author: Stephan_T
author_rank: Contributor
timestamp: August 19, 2015, 07:44:20 pm
content: Hi Rasz,Quote from: Rasz on August 18, 2015, 03:03:22 amAt that moment of the video, I was almost about to scream at the screen, but then Dave silently changed the multimeter. I think, there should have been a comment about the reason. The spec of the Brymen 257 (wich I also use) lists for AC:50 Hz ~400Hz. Showing the ripple on a scope would have been more educating.

author: Rasz
author_rank: Super Contributor
timestamp: August 19, 2015, 07:51:00 pm
content: Quote from: Godzil on August 19, 2015, 07:33:57 pmits not only text, it manifests in columns with high brightness(gamma) elements like icons, or whole test image from previous videobtw I would LOOOVE a video tutorial about driving modern LCD, what is exactly in the Tcon, how it all works, VCom, gamma, shifters and drivers, all that magical high speed digital/analog mess. Preferably done with help from someone who did it for a living.

author: Godzil
author_rank: Frequent Contributor
timestamp: August 19, 2015, 07:58:47 pm
content: Rasz: I didn't notice that but ok, make more sense in that case.That's still weird, I remember having strange behavior on some LCD panel with the timings was't correct, and having bar like that was one of the problem I had, but it was on really "old" technology like FSTN graphical LCD screen

author: rad.wiel
author_rank: Newbie
timestamp: August 19, 2015, 08:12:58 pm
content: Hi Dave!I just found some interesting info on one of Polish forums.http://www.elektroda.pl/rtvforum/topic2285209.htmlOne guy has similar problem and discovered, that there is problem with flat flex connectors and traces made on matrix glass. He used ohmmeter to check if there are connections between test pads on pcb and test pads on flat flex cables. As I can understand and translate he had no connection between test pad marked as "voff" and device called "side driver". He used thin copper enamel wire to make missing connections and this fixed the problem.Btw. All matrix made in Slovakia for Samsung in 2008 and 2009 has similar technical flaw (model of matrix: Ultra Clear PanelS-PVA 4ms).Sorry for my english.Photos (driver boards/flat flex can be different for different models)http://obrazki.elektroda.pl/8159757800_1380278939.jpghttp://www.elektroda.pl/rtvforum/files-rtvforum/bez_tytu_u_1716.jpg

author: averox
author_rank: Newbie
timestamp: August 19, 2015, 08:37:27 pm
content: Quote from: EEVblog on August 18, 2015, 07:27:37 amYou should try giving it another shot as some of the tabs can be simple or downright finicky to get the pressure right. I've had to get really tricky with some tabs before with shoving things under and then back on top to get them to work right. Don't burn your finger though because those pieces of silicon on the tabs do get quite hot. I've seen this a fair amount in TVs I've tried to fix but I wasn't able to fix them all despite trying my best.Good luck!

author: Ampere
author_rank: Regular Contributor
timestamp: August 19, 2015, 10:00:11 pm
content: Another great video, Dave. I always learn something from your videos. Especially the ones where you repair or design something.I do have a question. What is the freeze spray meant to do? How would cooling a component make it work (assuming it wasn't above its rated temperature beforehand)?

author: AF6LJ
author_rank: Unknown
timestamp: August 19, 2015, 10:04:04 pm
content: Good video and good troubleshooting..I am thinking bad conductors on the glass itself.This TV could have been struck or have fallen over for all we know, damaging the on glass conductors.

author: ultranalog
author_rank: Contributor
timestamp: August 19, 2015, 10:06:17 pm
content: Regarding the slow fading in of the bars: that looks like an analogue problem.Remember this is a TV from 2009 or so. The 'PC' input is 100% a VGA input. Have you tried selecting the HDMI?

author: N2IXK
author_rank: Frequent Contributor
timestamp: August 19, 2015, 10:16:20 pm
content: Cooling a component causes it to shrink and possibly deform enough to make/break a cracked solder connection. Cooling a semiconductor junction can help spot leakage currents, noise, voltage offsets, etc. that vary with temperature.In the case of BGAs, it can help find a cracked solder ball or poor joint under the package.My next step on troubleshooting this beast would be to scope all the power supplies for noise (bad caps) and then try a reflow of the main PCB. I really don't think this is a panel issue.Finding a used board on eBay is always an option. Have to decide if the monitor is worth the $80-$100 gamble, or find a seller who accepts returns. If you were able to troubleshoot the boards to component level, it would likely be one of the big custom ASICs anyway, which would be nearly impossible to get replacements for.

author: retrolefty
author_rank: Super Contributor
timestamp: August 19, 2015, 11:21:02 pm
content: Lots of guesses (too many really) on what the symptom cause might be, but to be honest I don't think it can be determined without using complete schematic(s), maintenance manual(s) and of course a good O-scope. The things tried (freezing chips, wiggling cable connectors, etc are only useful when not having the needed documentation, test equipment, and experience, and in that case it's as much luck as skill of being able to determine root problem.Still the tear down was very entertaining in seeing what all is included in a large LCD TV, pretty impressive tech on even this somewhat 'older' TV. I wonder now that prices have come down so much on this size what 'cost factor' changes have been made in more recent TVs? It sure is a large volume, low margin, consumer market. It's amazing how such a competitive market can keep giving us more and more for less and less. NASA could not design and build the same product to the same price point.

author: Ampere
author_rank: Regular Contributor
timestamp: August 20, 2015, 12:02:30 am
content: Quote from: N2IXK on August 19, 2015, 10:16:20 pmThank you for the explanation. I get what you mean. It's a way to tell whether there's a fault in an IC or its connections.I happen to have a bottle of duster spray so I might give this a try next time I'm trying to fix something.

author: Stonent
author_rank: Super Contributor
timestamp: August 20, 2015, 01:25:39 am
content: If you're going to toss out the TV anyway, I guess you have nothing to lose by baking one or more board that have BGA chips to get some of that cruddy lead free solder to reflow.When I had a Tcon board issue with a Westinghouse TV the issue wouldn't show up until the TV had been on for a little bit.

author: adcurtin
author_rank: Contributor
timestamp: August 20, 2015, 03:35:53 am
content: If you don't get a remote and go to the service menus and stuff, you should at least put an external signal into the thing. You can much better control what's displayed and help narrow down the problem.As others have said though, it makes a lot of sense for it to be a problem with one of the horizontal drivers.

author: pickle9000
author_rank: Super Contributor
timestamp: August 20, 2015, 04:08:33 am
content: Dave seems to get 100% working stuff or items destined for "silicon hell".

author: sean0118
author_rank: Frequent Contributor
timestamp: August 20, 2015, 09:43:12 am
content: I'm not sure if it has been mentioned, but could a failed crystal oscillator circuit cause this? I'm not sure how often it happens, but surely a crystal oscillator that has drifted out of spec would cause weird issues?

author: tom66
author_rank: Super Contributor
timestamp: August 20, 2015, 11:37:24 am
content: This is a defective LCD panel. I have heard some people soldering very thin wires to pads on the drivers on the side of the screen to reconnect an internally failed connection. But usually it cannot be fixed without replacing the screen, making the TV scrap.A temporary fix is to go into the service menu (TV in standby then press Mute 1 8 2 Power, or Info Menu Mute Power depending on the region) and adjust the "SUB BRIGHTNESS" or "SUB CONTRAST" figures, these can reduce the brightness to the point at which the pixels do not bleed.Sadly this is extremely common with large screen (32" or above) Samsung LCD TVs and as such I can never recommend anyone buy one.

author: Rasz
author_rank: Super Contributor
timestamp: August 20, 2015, 03:48:54 pm
content: Quote from: tom66 on August 20, 2015, 11:37:24 amI had a link somewhere to a .ro forum with a thread full of 'solutions' (pinout of tcon and tab test pads+what usually breaks for particular panels) for this very type of repair, sadly I cant seem to find it now

author: G7PSK
author_rank: Super Contributor
timestamp: August 20, 2015, 04:01:43 pm
content: My pennies worth, try a hair dryer on the screen this sometimes either proves the fault with the lcd and on occasions even cures it and I have no idea why it does.

author: Rasz
author_rank: Super Contributor
timestamp: August 20, 2015, 04:18:30 pm
content: Quote from: Rasz on August 20, 2015, 03:48:54 pmFOUND IT !https://www.eevblog.com/forum/repair/panasonic-lcd-tv-images-are-sluggish-and-go-into-each-other/msg657801/#msg657801http://monitor.net.ru/forum/topic375748-96.htmlIt would be epic if Dave managed to fix restoring individual tab connections, thats drunken russian level of hardware hacking right there.

author: JoeMuc2013
author_rank: Contributor
timestamp: August 21, 2015, 08:16:30 am
content: Hi Dave(s),why don't you get your Flir E8 out and check if anything heats up beyond reason? The fact that the bars are fading in feels for me like something might be becoming red hot during the first few seconds after powerup.Good luck anyway. This is very entertaining and makes up for a good troubleshooting guide.Regards,Joe

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 21, 2015, 08:45:29 am
content: Quote from: JoeMuc2013 on August 21, 2015, 08:16:30 amI think Dave already heated up enough stuff for nowHint: did you watch #782?

author: JoeMuc2013
author_rank: Contributor
timestamp: August 21, 2015, 03:24:17 pm
content: Quote from: PA0PBZ on August 21, 2015, 08:45:29 amWell, I did... after posting. Bummer!

author: qwertz
author_rank: Newbie
timestamp: August 27, 2015, 08:57:13 pm
content: Hi Dave,I think I know what cause this issue, because I already repaired a tv with exactly the same problem.The problem is located on the mainboard. There is a Samsung bga chip with some cracked solder balls. It is one of the two chips with a heatsink (the one which is closer to the t-con ribbon cable connector) . Just try to knock with a screwdriver on the heatsink, or bend the board a little bit.Regards,BenjaminEdit: O.Ops: Just saw that you destroyed the pcb in the next video... so my post is obsolete

author: bills
author_rank: Frequent Contributor
timestamp: August 27, 2015, 09:51:57 pm
content: BenjaminThanks for the tip I have one doing the same thing.I opened it up and reseated all the t-con cables and it worked until I turned it off than same problem.Now if i tap on the back it works until it cools off.I will check and re flow that chip.I will report results.This was a freebie that I use at my vacation home, may be a few weeks before I get back there.