> For example, LED TV use individual LEDs to switch on and off to construct a picture.
Um...
Did I destroy my friend's TV with a magnet? (2022)
41–50 of 59 posts
Re: Did I destroy my friend's TV with a magnet? (2022)
#42Earlier quoted context omitted.
People frequently rotate CRTs for arcade games. They're fine.
Actually, this is a perfectly good point - arcade games had their CRTs on a 45 degree angle, some on portrait and some on landscape direction, and they showed no "intermediate" effects that you'd expect if this gravity claim was true. There were even "table" video games where the CRT was 90 degrees upward, which should have really messed things up if this gravitational effect was at all true. Likewise, remember the g…
> Likewise, remember the green swooping radar of days gone by
Monochrome CRTs don't have a shadow mask or an aperture grille, and no degausing or need for it. Certainly, magnetic fields will interact with the electron beam of a monochrome CRT, but if it's the earth's magnetic field, it will be uniform over the whole screen, and not a big deal.
Re: Did I destroy my friend's TV with a magnet? (2022)
#43All quality CRT TVs are automatically de-gaussed on switch-on. That's the 'toooong' you hear when they turn on. A magnet might temporarily mess up the magnetic convergence with magnetised spot areas, but that should be fixed on next switch-on. The Earth’s magnetic field can also affect the picture That's because when the convergence controls are set correctly, they also take care of the magnetic field of the earth to…
> A magnet might temporarily mess up the magnetic convergence with magnetised spot areas, but that should be fixed on next switch-on.
A large enough magnet (or other trauma) can permanently warp the mask or grille --- this is basically unrepairable. The degauss system should undo magnetism eventually, but sometimes it takes several activations.
Re: Did I destroy my friend's TV with a magnet? (2022)
#44> There are many CRTs in your TV or monitor. They are each aimed to deliver electrons to a precise spot on the back of your TV where they excite the phospor in the tiny spot on your TV that the electron hits. Magnets are used to guide the electrons to that precise (and tiny) spot. The excited phosphor molecules at that spot then emit light. All the CRTs working together generate the picture on your TV. That's incorre…
> There's just one in monochrome displays or three in color displays.
the CRT is the giant glass picture tube, cathode ray tube, there is only one of those in a TV.
For color TV there are 3 "guns" shooting electrons at the different colored phosphors. There is a single system to guide all three electron beams to their respective right parts of the display.
http://www.learnersplanet.com/sites/all/sites/default/files/...
Re: Did I destroy my friend's TV with a magnet? (2022)
#45There's a throwaway comment in here about the earth's magnetic field affecting CRTs and turning the TV upside down, is that actually true? I would have thought the earth's magnetic field would be incredibly weak in comparison to the deflecting coils.
Correct, the field of the Earth is weak and won’t mess up the image on the TV.
Some professional Sony BWM series monitors have menu settings for the direction where the monitor is facing to compensate for the earth magnetic field.
Re: Did I destroy my friend's TV with a magnet? (2022)
#46Re: Did I destroy my friend's TV with a magnet? (2022)
#47Maybe worth noting in the context of HN: There are two types of electron emissions in a CRT. The primary emission, which produces the visible image, and the secondary emission, which causes an electron well around the excited spot, as free electrons take up positions of the electrons emitted by the primary emission. It's the latter that was utilized in the CRT memory Williams-Kilburn tubes (the first viable random access memory), which detected that local depletion of electrons in the phosphor in the read cycle.
Moreover, there were also dark-trace CRTs or Skiatrons (developed just before WWII and used for Radar during the war), producing a dark-on-light image, which were also based on the secondary emission, rather than the primary one. (Technically, this was based on the displacement of free electrons in an alkali-halide crystal lattice, which made the CRT locally opaque.)
Re: Did I destroy my friend's TV with a magnet? (2022)
#48When I was a kid in the mid 80's we had a ball lightning incident. Some family was over visiting and the adults were sitting in the adjoining dining room with us kids in the living room by the TV. Lightning struck somewhere close by and a tennis sized ball of electricity entered the dining room through the outside wall. It crossed the room in about a second, went through the wall to enter the living room and then acc…
From what I can tell, ball lighting doesn't exist. We have lots and lots of people who think they've seen it. But there doesn't seem to be any legitimate footage, which is pretty damning considering there are cameras everywhere now.
You’d think skeptics would learn their lesson after rouge waves. Tons of eyewitness accounts going back to antiquity but no footage, considered a myth for ages.
We even had a bunch of math saying they weren’t possible/probable! (Ex once in an 100M years or so) so they were quite sure of themselves.
The we started to get large scale buoy data and sure enough, rouge waves! (the math was wrong).
Our understanding of earth phenomenon is far from complete. For lightning, red spites/green ghosts/etc are all relatively new discoveries.
Re: Did I destroy my friend's TV with a magnet? (2022)
#49I ruined a Sony TV in the late 1970's with a pacemaker magnet my father (a physician) brought home from work. My parents were not happy with me. It was able to be repaired.
Re: Did I destroy my friend's TV with a magnet? (2022)
#50Back in the days when LCD computer monitors were ridiculously expensive for a 15" monitor, I was at a customer in NYC where they had hundreds rather than the standard 'tv' style monitor of the time. Turns out, they had moved to a new location too near the subway system - and every time the train went by, it would mess with the old displays. Apparently whatever savings they got from the change in location was gobbled up by needing that cutting edge hardware.