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Hi, I have a sd telly (sony trinitron) I have just noticed the colour on each end of the screen is a different colour to middle of the screen, I've had the telly about 7 years,
Many years ago I had a pal who was an engineer for a TV rental company. He once told me that, if a customer complained of picture deterioration on their rented TV, a short-term solution could sometimes be to bash the electron gun part of the CRT with a rubber mallet! Apparently this dislodged some sort of deposits that caused picture deterioration.
DON'T try this at home, children!!
Seriously - don't try it. There can be very high residual voltages in a TV's innards.
I echo what iscanut has said. A good excuse to treat yourself to a whizzy new digital HD job!
I hate to confirm your belief, but virtually exactly the same happened to my Trinitron after around 10 years. Then, shortly after the colours went awry, I turned it on one day and it gave a `cough` and it was over. A quote for a repair was around £100 so I went for a new one.
Do you have any electro-magnetically devices close to the TV like normal speakers, which will
cause the TV colour guns to change colour
Speakers for a normal TV is shielded to stop the electro-magnetically field from affecting the TV tube
The scan coils could have slipped down the neck of the tube causing purity errors. It's a fairly common problem. That would give colour registration problems all around the screen leaving the central part OK.
If that is the problem it's very easily put right, no parts required. Usual warnings apply re hi voltage, there's 27000 volts in there when it's on.
that seems to be the problem I'm having, the central part is normal, how do I fix scan coils, is it just a case of taking the back off, I've never been into the back of a telly. i'll do a google and see if it'll show up.
I seem to of fixed it, I gave the telly a really good shake, and the picture is back to normal, I also moved the christmas tree that was next to the telly, so I don't know if it was shaking the telly or moving the christmas that did the trick
At least you didn't try poking around the inside of your TV.
There are some seriously high voltages knocking around.....
However, I wouldn't knock a Trinitron/Diamondtron TV around too much (if at all) because of the tube's aperture grill technology.
Even with the TV switched off and disconnected from the mains, there are still some very serious amounts of voltages that can prove very painful! Do not go into the back of a TV if you don't know what you are doing!!!!
When the television is switched on from cold via the mains on/off switch ( not from standby) then for the first few seconds a part called a degaussing ptc allows current to flow through the degaussing coils fitted around the tube and it demagnetises the tube. The ptc then switches off and does not operate again until the set is switched on from cold via the on/off switch. If the set is only ever switched off /on via the remote then the demagnetising / degaussing circuit never operates. As the ptc gets very hot for the few seconds that it is on it is quite common for one of its solder connections to melt slightly resulting in a “dry joint” It is also common for the internal parts of the ptc to go intermittent. Banging the set may temporally cure the set but if it is a dry joint this can get worse eventually burning a hole in the pcb. Though often it will blow the fuse causing the set to go dead first. The trade price of a ptc varies from about £2 to £8. Depending on the type.
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