TV has gone purple!

[bster]

Not sure if this is the right forum but......

Woke up this morning and my 2-3 year old CRT 32" BUSH TV picture has gone psychadelic!. I take it its the cathode tube thats causing the prob?

I remember sticking a magnet in front of a TV once and this had the same a effect as the one that has messed up now.

so is it a new TV or is it fixable?

 

[breezer]

your tv has 3 electon emiters (aka "guns" ) one red, one blue , one green

purple is a mix of red and blue, which means the green colour is missing.

this can sometimes be fixed with a very technical procedure.

THUMP IT (but only once)

 

[Sleepyhead]

That, Breezer, is commonly referred to as HVIT (High velocity impact technology).

 

[bster]

did a search and read about degausing (or sumthing), anyway waved my telescopic magnet around the screen to demagnetise (or magnetise) and its ok ....for now!

probably get a new TV (it cost £200 and i take it it'll cost upto a hundred to get an engineer out).

 

[JohnD]

If you switch it off, then on (with the button on the telly, not the remote standby) you may hear a momentary "thump" as the built-in degausser works.

IIRC they automatically operate when you turn it on (or off). Useful if you have been parking it next to unshielded louspeakers or other sources of magnetism.

The degausser can fail, shouldn't be a complicated repair but may not be worth it.

 

[tockworth]

Johnd has hit the spot you have what is called a purity fault. This is when the crt has become magnetised to the extent were it deflects the electronic beam so the beam hits the incorrect phosphers giving the incorrect colour.In every tv there is a degauss circuit which operates on switch on for a fraction of a second which magnetically sweeps the crt and purifies it of any residual magnetism. It is this circuit were the problem lies. It may only be a dry joint in this circuit as it is quite a high current circuit,or it could be a component breakdown.The very worst scenario is that the shadow mask in the crt has dislodged giving these errors but unlikely.

 

[bster]

so its worth opening up and checking the boards for any signs of the obvious then.


BTW - we always switch it off at the plug whilst the tv is ON, left it overnight (unplugged-as always) and it has same fault this morning

 

[JohnD]

If you switch it off, then on (with the button on the telly...

 

[tockworth]

If you are switching off at mains socket then back on the same way the tv is only coming on from standby. This would mean the degaus circuit never gets a chance to operate.There would have been a gradual build up over time which has led to the impurities you see now. It may now take some time to get back to normal as this circuit only operates on switch on from stone cold. My advice would be over the next week or so is to close it down correctly ie after use switch off at on/off button on tv then switch off or pull plug out of mains socket then reverse for switch on next day.On at the mains socket then on by the tv on/off switch.

 

[TicklyT]

It's worth bearing in mind the strong magnetic fields from audio speakers, and the possible effect they may have on a CRT screen if they are placed too near the the TV set.