blue lines ?

[mo]

one of my tvs , a philips 100 hertz model is showing blue lines going across the tube.its been like that for about 6-7 weeks.
it shows up more in dark shots .
the tv other than that works fine .
i at first thought that it was some electrical interference,but i havn't done anything to prove that.
so, any ideas anyone ?

thanks

[ScootermanRoger]

Are the lines slightly diagonally slanted? If so, it sounds as if the flyback suppression is faulty, which could mean anything from an individual component failure on the blue output, to the A1 (background) control for the tube being set too high, (this acts like a preset brightness, and is usually found beside the tube focus control sticking out of the line output transformer, - beware high voltages), to a fault on the tube itself.
If the lines are exactly horizontal, then it won't be any of the above, but more likely to be a processing fault (or feature) within the set's video circuitry.

[mo]

hello scootermanroger,

i think they are as you describe.
any ideas of how long this can on for without it spoiling the picture too much?
is it likely to get worse?

thanks for the reply

[ScootermanRoger]

Is it still under guarantee? If so, get an engineer to assess it. If it's out of guarantee, I suggest you find someone local to you to have a look at it and give you another opinion. The problem is it could be one of many different things causing what you see, ranging from the trivial (minor adjustment) to the extreme, (internal tube-neck fault)
Let's hope it's a trivial fault!

[mo]

hi,
all i want to know is assuming it is what you say it is.
do you think it can last a few more months as it is ?
its five years old and really dislike the thing.
i'm not a fan of philips tv.
i am not in the mood to fix it unless i really have to
thanks for all your help

[ScootermanRoger]

Originally Posted by mo

hi,
all i want to know is assuming it is what you say it is.
do you think it can last a few more months as it is ?

How long is a piece of string??? Your question is unanswerable I'm afraid, and even if the exact fault is diagnosed, it's all down to luck!
Example: My very ageing Panasonic TX-33A1 suffered a tube-neck fault (the whole screen went bright blue) many years ago. I cranked up the brightness and the contrast to maximum and gave the tube neck a few sharp taps with the handle of a large screwdriver*, it cleared and it's been alright** ever since. Then, a couple of years ago, the same thing happened with the green gun, so I cranked up the brightness to maximum and it cleared itself without any tapping of the tube-neck.

*YOU DO THIS AT YOUR OWN RISK!!!
**Only "alright", but the tube is now VERY low emission, with a pasty purply look to the picture. I'm currently considering it's replacement. But with what? Must be 36" w/s crt.