Do plasma screen have explosion risk? (Solved) - Page 1
Forum section: electronics / beginners

author: sam1275
author_rank: Frequent Contributor
timestamp: July 26, 2016, 06:32:58 pm
content: Hi everyone, I think I've read from a unreliable source that plasma TVs can explode, is that true? Thank you.

author: JacobPilsen
author_rank: Regular Contributor
timestamp: July 26, 2016, 07:52:04 pm
content: 0.6 of atmospheric pressure.(Even if you use hammer, it's not worse than ordinary window.)

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: July 26, 2016, 08:11:50 pm
content: Plasma TV's are highly dangerous and subject to explode at any time, provided the empty spaces in their housings are filled with unstable explosives.Otherwise, I don't think there's any danger.

author: Monkeh
author_rank: Super Contributor
timestamp: July 26, 2016, 08:14:34 pm
content: Quote from: Melt-O-Tronic on July 26, 2016, 08:11:50 pmWe must deal with them.

author: VK5RC
author_rank: Unknown
timestamp: July 26, 2016, 11:17:22 pm
content: With the RF hash they generate I will happily join the "war against plasma TV s"! HiHi

author: timb
author_rank: Super Contributor
timestamp: July 26, 2016, 11:29:17 pm
content: Quote from: VK5RC on July 26, 2016, 11:17:22 pmSo, it's not just my specific TV then? That makes me feel better! Awhile back, playing with an old analog scope I noticed a ton of interference!With the probes connected to the scope, but not actually probing anything, if I set the trigger to Line (at least I think that's what it was set to), I would pickup a signal a few hundred mV in amplitude. I happened to shut off the TV and notice it completely go away...I thought that maybe it was the fans inside the TV or something generating line noise. (My TV is a Panasonic Plasma circa 2008.)You know, I can actually hear when the TV is on (but muted). It's some sort of very soft high frequency buzz. Hard to describe. It reminds me of a CRT TV. I remember as a kid, being able to go into someone's house and know if a TV was on anywhere inside, just from the HF sound (I assume) the fly back supply generated.

author: Monkeh
author_rank: Super Contributor
timestamp: July 26, 2016, 11:33:08 pm
content: I can actually hear the LCD TV downstairs, as well.. Very notable change in tone when displaying a black image.Usually drowned out by the high frequency whine of the blu-ray player's standby supply.. Still having a decent hearing range is a curse.

author: Brumby
author_rank: Unknown
timestamp: July 27, 2016, 01:03:30 am
content: Quote from: sam1275 on July 26, 2016, 06:32:58 pmA very unreliable source.The only risk of explosion I can foresee is if something like an electrolytic capacitor decides to curl up its toes and go out with a bang....... but then this applies to just about everything electronic. (I had a MOV go short across 240V mains once. It got my attention!)Even then, it'sextremelyunlikely to have any shrapnel flying around the room.

author: VK5RC
author_rank: Unknown
timestamp: July 27, 2016, 11:04:45 am
content: @Timb I can't find a good reference to where exactly the noise comes from inside the TV, but I think it is commonly the actual screen. All manner of electronic devices with switch mode PSUs generate a huge amount of RF noise, to the point where I can't use the HF bands for anything other than local broadcast stations where I live, The difference in background noise out in countryside is dramatic.Below is a link to one such Amateur radio issue, note it is quite old, LCD TVs do seem a bit quieter but I suspect all the cheap SWPSU have been responsible for keeping the noise level up. Broadband over power line is also another great source of RF into the whole district.http://www.eham.net/articles/4285

author: Kilrah
author_rank: Unknown
timestamp: July 27, 2016, 12:12:33 pm
content: High frequency low voltage digital signals can already be a pain, so imagine what high frequency HV digital signals do...I never liked Plasma TVs. Expensive, power hungry, noisy, shitty contrast, and screen burn in... Fortunately large LCDs came before I could afford one anyway

author: bktemp
author_rank: Super Contributor
timestamp: July 27, 2016, 12:19:05 pm
content: Quote from: sam1275 on July 26, 2016, 06:32:58 pmYes:https://www.youtube.com/watch?v=LhPdqdvlDoY&feature=youtu.be&t=148

author: Seekonk
author_rank: Super Contributor
timestamp: July 27, 2016, 12:25:52 pm
content: I smashed one without issue to salvage the aluminum backframe. Something not worth doing. I was given this set. I was barely able to get it in my truck it was so heavy They do have an excellent collection of FET.

author: klunkerbus
author_rank: Unknown
timestamp: July 27, 2016, 12:26:28 pm
content: I've avoided plasma TVs in part because of how many people complained about the buzzing noise the technology makes, especially on early models. Search on "plasma TV buzzing" for references if this is news. And then there's the heat they emit from the screen...

author: Kilrah
author_rank: Unknown
timestamp: July 27, 2016, 12:33:33 pm
content: Quote from: bktemp on July 27, 2016, 12:19:05 pmWow, they didn't do half a job with the amount of 'splosives they put in thereIt got what it deserved

author: timb
author_rank: Super Contributor
timestamp: July 27, 2016, 04:16:53 pm
content: Quote from: Kilrah on July 27, 2016, 12:12:33 pmActually, plasma TVs have really good contrast and much richer blacks compared to LCDs. All in all, if you compare an equivalent size LCD and plasma set of the same time period, the plasma will always have a better picture.This comes at the cost of heat, power consumption and weight (as you mentioned). Burnin is also a very real issue (my parents have a 10 year old set that has a certain cable news network's logo box and ticker permanently burnt into the bottom of the screen, courtesy of my father).On the upside, modern plasma burnin isn't like old monochrome CRTs (or early "orange plasma" displays used on Toshiba and Compaq transportable computers) where the actual text literally burnt into the screen. On plasma TVs it's more like a faint pink "smear" in the general shape of the image, and it's only really visible on a solid white background.All that said, my plasma set has lasted 10 years with no issues. I'm overall very happy with it. It's held up a lot better than any LCD of similar vintage that I know of. It's a shame they didn't keep developing the technology further, but I guess you can't compete with the cost/performance ratio of an LCD!

author: Kilrah
author_rank: Unknown
timestamp: July 27, 2016, 04:30:58 pm
content: Quote from: timb on July 27, 2016, 04:16:53 pmOnly if a crucial condition is satisfied... no or little ambient light.An unpowered or black-displaying LCD in daylight is reasonably deep black, a plasma is pretty light grey. The more ambient light the less contrast, a plasma in a well lit room is horrid.Quote from: timb on July 27, 2016, 04:16:53 pmI guess burn in is not much of a concern in a standard home TV setting indeed, but I can tell you I've seen so many plasmas "misused" as 24/7 display panels in airports, stations etc when that was common that it's not even funny anymore. The text/logos definitely get engraved given enough hours, sometimes that would become visible already after a year or 2, when the intended lifetime of the installation was meant to be 5-10 years...For me both the ambient light thing and the burn-in would have been a problem given that my TV is also my computer monitor.

author: MosherIV
author_rank: Super Contributor
timestamp: July 27, 2016, 04:37:03 pm
content: I have agree and back up timb.By the way the 2 technologies work, Plasma must have better contrast than LCD.Plasma TVs work in the same way as old CRT tubes do - they bombard a fluorescing material to create the colour picture.This creates a high contrast between colours and black.LCDs on the other hand use the light blocking feature of LC to stop the back light going through a colour filter.Black is never truely black on a LCD, there is always some back light bleed through because the LC is not perfect at blocking the light.

author: sam1275
author_rank: Frequent Contributor
timestamp: July 27, 2016, 04:42:30 pm
content: Thank you everyone!!!

author: Kilrah
author_rank: Unknown
timestamp: July 27, 2016, 04:49:20 pm
content: Quote from: MosherIV on July 27, 2016, 04:37:03 pmYes, but some that I've seen (maybe they were just poor quality...) had the same problem as some CRT's, where an area/pixel that's supposed to be black isn't completely turned off, and thus still emits a bit of light with the same result as an LCD. Was told that while in theory an off pixel should be off because it's indeed emissive (which was of course well marketed) in practice driving circuitry couldn't quite do that and had leakage.Anyway, the new Plasma will be OLED. The first generation of large panels a year or 2 ago still had an issue that is actually also common on plasmas, which is poor pixel fill rate (excessively thick black grid visibly separating the pixels).I believe I've seen a couple in stores that looked better now. Too expensive though.

author: tooki
author_rank: Super Contributor
timestamp: July 27, 2016, 06:23:07 pm
content: Funny that this thread came up now, as I was just killing time at a gadget store and was looking at LG's OLED TVs. And I must say, the image is absolutely gorgeous. Black really is black. (And white really is white; these sets use white pixels in addition to RGB.)In any case, I have yet to own an LCD TV (I have a 42" top of the line 2008 Panasonic plasma, and it's great), and it's unlikely I ever will, OLED just looks so much better. Now if only the 65" didn't cost $5500.... (And I had a job, LOL.)As for why some LCDs buzz, my guess is it's the PWM dimming of the LED backlight during dynamic contrast. (The plasma is similar.)

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: July 27, 2016, 06:31:44 pm
content: Quote from: Kilrah on July 27, 2016, 12:33:33 pmHow about that? Somebody read my post, set up a demonstration to prove it, went back in time and posted it on YouTube!

author: Brumby
author_rank: Unknown
timestamp: July 28, 2016, 03:09:39 am
content: Quote from: MosherIV on July 27, 2016, 04:37:03 pmOn paper, you're right - but in real life, ambient light will affect perception... and that's what matters.

author: tooki
author_rank: Super Contributor
timestamp: July 28, 2016, 10:03:18 am
content: And LCDs, by virtue of being light valves with a separate backlight, can employ immensely bright backlights, which is advantageous if you have a very bright room. (Plasma is great for a typical American living room, but in a top-floor apartment in a new building here in Switzerland, where half the walls in the living room are floor to ceiling glass, plasma could struggle on a bright summer day.)OLED looks to be able to keep up with bright LCDs as best I can tell.