Green patch on TV [Archive] - Forums @ The Digital Fix

jerryg

03-01-2002, 13:01

My TV decided to bring the new year in with a green patch on the right hand side of the screen. It lasted two days and then the next day just went away. I haven't tried it today to see how it's doing.

A friend reckoned it was just dust caught behind the screen. Is he right? Or was it the prelude to my TV turning everyone into little aliens before the tube blows up?

Any thoughts gratefully recieved.

Bapapapa

03-01-2002, 13:06

Speaker too near the TV?

jerryg

03-01-2002, 16:26

Shouldn't be the speaker as it's the one that comes with the TV and slots onto the side of it.

If it's an electrical disturbance thing, could a multi-socket that's on that side of the TV be the cause? I did leave the Xmas lights on all night by mistake after a few festive drinks.

skeletonbob

03-01-2002, 20:09

yep could be indeed, although i have never heard of a mutisocket causing that much grief so as to turn a screen green.....

green=electrical~magnetic source

:( shame u cant deguause tv's....

send it back....

john316

03-01-2002, 21:00

It wouldn't happen to be a Toshiba 28W93B set would it?

Martin Veenman

03-01-2002, 21:40

Originally posted by skeletonbob
:( shame u cant deguause tv's....

I thought TVs degaussed when they're switched off?

04-01-2002, 01:38

My mum and dads new TV did this over christmas, and they had an engineer out to it two days ago. Basically the engineer (who claims to work on warranties for Toshiba, Philips, Sony...) told me...

This is a phenomenon that seems to effect many widescreen TV's that are over 25" in size. Typically you will find a green patch on the top right, and a blue patch on the left, each the size of a duck egg. The manufacturers are still investigating this, but have found a temporary fix to be to lower the contrast to 49%, and to boost the brightness by 2%. It seems that when the contrast is high (ours was on the default setting of 70%) that the TV is having to work too hard, and being a widescreen the guns can't all keep up.

He did exactly this and the patches have gone! Even though he has messed with the settings, the picture looks just the same to me! Try it, I'd be intrigued to hear if it really is the problem...

He also mentioned that even when knocking the contrast down you may get smaller patches the size of 10 pence piece - just knock the contrast down another notch and these should disappear!

He also recommended switching the TV off at the switch, over night or when it won't be used for long periods of time, as certain reset actions don't happen with the simple standby on/off.

Ian

jerryg

04-01-2002, 08:07

Thanks for the advice. I can rest assured that it isn't the tube on the way out as the set is a good few years old, albeit a good one. I'll give the contrast setting a go next time I see little green men :)

jerryg

04-01-2002, 08:15

John 316,

No, the TV is an old Sony.

I reckon the problem was either the xmas lights on (they did have a huge adapter), or the new table light my girlfriend has just informed me that she put on top of the TV for the night.

GidGrace

04-01-2002, 10:47

It will almost certainly have been the adaptor you mentioned in your last post.

Adaptors contain coils of wire wrapped around metal sections (think electromagnetic effect).

If this is left near your TV, you will certainly see the magnetic effect. If you leave it too nearby on a regular basis, you could damage the tube.

Here's a quote for you which explains how they work...

To do its magic on the high voltage and change it to low voltage the transformer uses two rather intriguing and important phenomena. Firstly whenever an electric current flows, there is magnetism around it. Secondly whenever a magnetic field changes (by moving or by changing strength) a voltage is made. If there's a wire close by when this happens then a current will flow in the wire as the magnetism changes.

The transformer takes in high voltage electricity and lets it run through lots of coils wound around an iron core. Because the current is alternating the magnetism in the core is also alternating. Also round the core is an output wire with less coils. The changing magnetism generates a current in the wire and less coils means less voltage. So the voltage is 'stepped-down'.

Gid

cjb110

04-01-2002, 13:02

is the problem any thing like this http://uk.photos.yahoo.com/bc/c1j1b0uk/vwp?.dir=/Home+Cinema&.dnm=2001+Colour+Problem.jpg&.src=ph&.view=t&.hires=t

If so then great, I'll do that on mine.

I only get this problem on bright areas through the dvd player (LG 3350). If I just use cable (telewest) I don't get the problem.