wow something wierd happened. lightning struck a house right across the street from me, sounded like a bomb went off. scared the bajeezes out of me. anyway i was watching TV at the time with my panasonic TV (not sure what type or how to find out), now there are inverted patches of color on the corners of the screen. it looks like sombody screwed up the tint on 3 of the corners of the screen. how do i fix it? do i have to buy a new TV now? somebody please help!
Hello, Reck! You wrote on 22 Sep 2005 01:42:15 -0700:
R> wow something wierd happened. lightning struck a house right across the R> street from me, sounded like a bomb went off. scared the bajeezes out R> of me. anyway i was watching TV at the time with my panasonic TV (not R> sure what type or how to find out), now there are inverted patches of R> color on the corners of the screen. it looks like sombody screwed up R> the tint on 3 of the corners of the screen. how do i fix it? do i have R> to buy a new TV now? somebody please help!
The lightning has knocked out the de-gauss circuit and the shadow mask has become magnetised. It's a straitforward fix if you have it done. No need to throw away the set, shouldn't cost a lot.
With best regards, 3T39. E-mail: snipped-for-privacy@hotmail.com
A lightning flash can generate a big enough electromagnetic pulse to magnetise the shadow mask. It might clear up on its own after a few on/off power cycles. OTOH, it might need a proper degauss with a degaussing tool.
Lightning generates a magnetic pulse which affects the shadow mask in your tube. In very simple terms, the shadow mask is a very fine metallic mesh just behing the front of the screen which guides the electron beams onto the correct colour phosphor dots. When it becomes magnetised, the electron beams are 'pulled' slightly and fall onto the wrong dots, creating the patchy effect.
Luckily, there is a device inside your TV called a 'degaussing coil'. When you power on the set from cold, you may hear a buzz or surging noise. That is the coil automatically removing any residual magnetic field from the shadow mask. It is necessary because a shadow mask can become affected by other means than lightning strikes, such as nearby magnets, like in loudspeakers.
Unfortunately, a very large magnetic field can severely magnetise the shadow mask to such a point that the built in degaussing coil is too weak to remove it in a single, or even several, cycle(s). Also, a lightning strike can damage TV circuitry so as 3T39 mentioned in his post, there may be physical damage to the degaussing circuit.
However, the good news is that even if the degaussing circuit is damaged, the repair should be trivial and not expensive. Conventional degaussing circuits are theoretically far less susceptible to lightning strike damage than the rest of your TV's circuitry, so the fact the TV still otherwise works OK bodes well.
Try a few on/off power cycles (switching it off properly, not standby) and see what happens. To do this you need to power on from cold, switch off, leave for a few minutes and repeat. See if this makes the colour patches fade. On powering on you may hear a slight momentary buzz or surge, which will be the degaussing coil working to remove the magnetism from the tube.
If this doesn't work, (it might take several on/off cycles, or the patterns may fade themselves over several days) contact a TV repair shop and get it degaussed, and repaired if there's a fault.
I'd first turn it off and let it sit for an hour or two then turn it on, repeat a few times if necessary, then take it to a shop if it's still messed up.
I recall a poster here from years ago who had a set that had a purity problem when placed in a particular corner, and it was determined that the steel-beamed building in which he lived had been hit by lightning at one time.
A soldering iron will perform a degauss, won't it?
A soldering *gun* will do a passable job...big high current transformer. An iron is useless for this.
This is a fairly common problem with nearby lightning strikes and almost always takes care of itself with repeated on/off cycles (if it hasn't done so already).
Figgered you did...just couldn't stand the thought of some newbie going to Rat Shack, purchasing a $10 iron, waving it around in front of his set and wondering why it didn't work.....
Let's see...holding the gun sideways to the screen, plugged in, hold trigger in while moving the gun in circles, first close to the screen, then moving it farther away. Is that right?
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