wierd colors!

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:

 

Possible, but not especially likely IMHO.

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.

Dave

 

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.

Dave

 

If you carry the set into the shop, it can be degaussed in literally
less than one minute.

H. R.(Bob) Hofmann

 

If you carry the set into the shop, it can be degaussed in literally
less than one minute.

H. R.(Bob) Hofmann

 

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?

Tom

 

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).

jak

 

Darn...was thinking gun, typed iron.

Tom

 

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.....

<G>

jak

 

Hi Tom...

You're forgiven

There'll be a penalty, however Your penalty shall be to explain
for the benefit of the op just how to go about using it as a degausser.

Can't shake the image of someone pointing the gun at the crt and
firing off shot after shot after shot...

Take care.

Ken

 

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?

Tom

 

[/QUOTE]

So I've wasted half a can of butane trying to degauss my monitor
with this Portasol iron then?

Dammit.

 

So I've wasted half a can of butane trying to degauss my monitor
with this Portasol iron then?

Dammit.


[/QUOTE]
Well, at least you probably 'did' get rid of the weird colors....
<g>

jak