Delete Delete Delete - Page 1
Forum section: electronics / beginners

author: The_Almighty_Bacon_Lord
author_rank: Contributor
timestamp: December 29, 2016, 11:05:40 pm
content: Delete Delete Delete

author: mzacharias
author_rank: Frequent Contributor
timestamp: December 29, 2016, 11:07:21 pm
content: I would say - yes it's caused by the water.

author: Adam60
author_rank: Regular Contributor
timestamp: December 31, 2016, 11:44:00 pm
content: What make and model TV is it. The tag is on the back of the set. Include pictures of the problem. Not likely caused by rain. Boards will dry.

author: wraper
author_rank: Unknown
timestamp: December 31, 2016, 11:53:01 pm
content: No chance to be water damage, with water damage you will get stains in the backlight. This most likely is mechanical damage of the LCD panel. It may mostly disappear by itself if the mechanical impact happened recently, or may not, depends on your luck.

author: Brumby
author_rank: Unknown
timestamp: January 01, 2017, 01:11:07 am
content: Just one point of clarification - it's not a Plasma screen, it's an LCD. (Says so on the back.)As for the damage - that is interesting.From the photos supplied, it seems that the green and blue subpixels are not noticeably affected (de Moivre patterns allowing) - and that the problem is only seen with image content that has red.... Is this correct?If so, then the likelihood of it being water damage to the panel is hard to imagine. How can a fluid affect only red subpixels in a collection of red, green and blue? The only thing I can think of is a substance that passes green and blue light relatively unaffected, but impacts red. Not getting any light bulbs on that one.Also, the damage does not appear to have any digital structure to it, so it is again difficult to point the finger at a dodgy/water affected connection.Intriguing.Would love to be able to inspect this in person....

author: Adam60
author_rank: Regular Contributor
timestamp: January 02, 2017, 11:42:01 pm
content: Problems of this nature inLCD often point to the main power supply board as the cause. If you are comfortable working on a live TV set and have enough experience, you could measure all the voltage values as labelled beside the connectors. The Vs and Va vakues will be on a tag inside the set. Look very carefully at all of the capacitors for signs of leakage or domed tops. These would need to be replaced. Generally the first ones to go are in areas of high heat, near MOSFETS heat sinks or transformers.if you areuncomfortable doing this, take it to someone who knows what they are doing. There is lethal voltage back there.

author: edy
author_rank: Super Contributor
timestamp: January 02, 2017, 11:59:21 pm
content: Have a look at this thread here on EEVBlog and see what happened:https://www.eevblog.com/forum/repair/laptop-screen-issue-help-diagnoserepair-needed!/Basically the same sort of thing but on my Thinkpad LCD screen. If it's the same sort of issue, it may resolve on its own, or may need a stuck-pixel tool. The liquid crystal may be stuck. Anyways, see the thread above and you'll notice my problem CAME SUDDENLY and then it took about a week but it eventually FIXED without me opening anything. Still good to this day... still no idea how it started. My Laptop was never outside, never got water on it.Our symptoms/pictures look very much like the same problem.... almost like the display is cracked or leaking... but it isn't.Here it is a few days progress, playing with a pixel-stuck tool and just using the computer and I guess the screen refreshing:And then about 1 week later it all but disappeared with no trace!Odd huh?Read my thread above, and whatever you do... DON'T TAKE IT APART!

author: edy
author_rank: Super Contributor
timestamp: January 03, 2017, 12:41:04 am
content: I'm in Toronto, and I also have no idea why it happened to my laptop LCD either. I suggest using a stuck-pixel program on your computer and outputing it to the TV (plug it in via VGA/HDMI). Put the program to mess around the pixels in that region only. There are a bunch available out there, some even on the web...http://www.jscreenfix.com/I would simply wait and see what happens. There is nothing you can do to fix it by taking apart your TV at the moment. The stuck pixel program may do absolutely nothing... but force you to wait and resist the urge to mess around with the TV... at least until the issue resolves.

author: wraper
author_rank: Unknown
timestamp: January 03, 2017, 12:46:40 am
content: Quote from: The_Almighty_Bacon_Lord on January 03, 2017, 12:40:33 amI guess it's one of those cases when some guys, no matter what the problem is, right away blame the PSU and suggest to replace capacitors no matter what.

author: Brumby
author_rank: Unknown
timestamp: January 03, 2017, 03:03:08 am
content: Quote from: The_Almighty_Bacon_Lord on January 03, 2017, 12:53:37 amI know it's not going to be a great loss if you trash this thing completely ... but I get nervous when people talk about applying heat to an LCD panel.Also, thanks for the invitation, but being in Sydney makes a visit a tad pricey.Revisiting the problem, it seems curious that the damage is primarily noticeable in one of the primary colours - but aside from that, the shape is, to my mind, very consistent with water intrusion.I did have a thought though - as to whether there might be an effect of water on the polarisation orientation. LCD displays have two polarising layers. One is the LCD sheet itself, where the polarisation is controlled by electrical signals. The other is a fixed polarising filter. If water were to getin betweenthese, then I wonder what effect would be seen?I have a couple of old LCD screens with failed backlights that I might like to have a play with - but time is my enemy at the moment - and I would have to clear off a large area to open up the one I would prefer to use.As far as opening up LCD TVs is concerned, my experience is very limited. I haven't opened up units as old as yours and from a couple of Youtube videos I've seen, they could involve a fair bit of mechanical disassembly, which might be involved. The oldest unit I've opened up is a 5 year old Samsung TV - and it consisted of wrangling a few screws and a lot of plastic clips which weren't too hard to manage (with a bit of care, of course). If you want to try this, set yourself a flat area, twice the size of the TV, with something soft to protect the screen. Most of the disassembly requires normal care - but when you get to the edge of the LCD panel itself, you will encounter a mass of edge connectors. Treat these with extreme care. My only purpose for going to this extent would be to separate the polarising sheet from the LCD sheet and use a lint free cloth toverycarefullyclean the two facing surfaces - then reassembling and see what happens.But, to be honest, I would put this down as a last-ditch effort.

author: Brumby
author_rank: Unknown
timestamp: January 03, 2017, 03:13:54 am
content: Quote from: edy on January 02, 2017, 11:59:21 pmI read that thread - and I must admit I've not come across "gluggy" crystals ... but there's a lot I don't know.Interesting ideas there - and the various forms of "exercising" the liquid crystal could be certainly worth trying. Even if they don't work, it would be useful to know .... and if they DO work, then bonus!

author: Adam60
author_rank: Regular Contributor
timestamp: January 05, 2017, 11:21:01 pm
content: So I was shot down by the one hit wonder "wraper", but I was wondering if you ever did take my advice and check your power board for voltage and have a look over the capacitors. Just curious to see if there were any issues found,