Monitor Flickering!!!

[Biplav]

Ok i got this LG 775n model 17inch Crt monitor(5yrs old)
today the monitor started flickering and the size is reduced to 12-13 inch.(and it keeps changing)
the edges flicker constantly and i am unable to c the taskbar or the icons on the top of the desktop.
This is Just like a Picture tube problem on ur TV set(thats when the veiwing area is drastically reduced vertically.
can u plz tell me how to solve this problem and how much will this cost.
i knw this monitor is old but not at a position to buy a new one so plz suggest bout the repairing before i finally land up at the LG service centre

[AlienTech]

Looks like your high voltage transformer is about to go. Sometimes hitting it to loosen the gun a little might help since it does not have enough power to get it unstuck itself. IE the actual picture is just a dot, the TV scans the lines from the top to the bottom of the screen drawing it a dot at a time. Or 3 dot for color. When your high voltage transformer has problems, it cant move the gun well enough using the magnetic coil found at the back of the picture tube.. It could be another problem, but it all has to do with the high voltage circuit and need a qualified technician to fix it.

[pimpom]

It's highly unlikely to be the picture tube and probably not the high-voltage transformer.

From your description, I gather that only the vertical size (height) changes and not the horizontal size (width), or at least the change in width is minor compared to the change in height. Correct ? If so, the two most likely causes are -

1. A dry solder or loose connection in the vertical deflection circuit.

2. A part called a preset potentiometer inside the monitor is defective. This component is adjusted at the factory to set the height to the proper size. The external controls change the size above or below this preset size.

There are other possibilities, but these two are the most likely ones. If it's one of these, it should not be difficult for a good technician to find out and correct the problem.

[Biplav]

yes the horizontal width remains the same only the vertical allignment changes.
but the problem is the size is now reduced drastically and i cant c anything and it flicker s constantly.
so wat i wanna knw is how much will it cost me.

[pimpom]

Sorry, but it's not really possible to give an accurate estimate of the repair charges. One reason is that the exact cause is not yet known. Even if I were to undertake the work myself, I still wouldn't be able to cite an accurate figure until I have had a chance to check it out. As I said, there are other possibilities besides the two I gave.

The second reason is that different repair centres/shops will have their own charging criteria.

If the fault is a dry solder and the technician locates it quickly, it's a very simple job and the charge should be quite small - perhaps a hundred bucks including opening and closing and testing.

If the preset potentiometer is defective and has to be replaced, the component itself costs only a few rupees and should not cost much more than the first possibility.

However, the defect may be more difficult to locate. Most parts involved with symptoms like this are not very expensive, usually less than Rs.100 each. But the tech will have to base the repair charges on how difficult it is to isolate the defect.

I suggest you visit a repair shop, describe the symptoms and ask them to quote an estimate, and also ask them to cite a maximum that will not be exceeded in any case.

[AlienTech]

//I suggest you visit a repair shop, describe the symptoms and ask them to quote an estimate, and also ask them to cite a maximum that will not be exceeded in any case.//

Without knowing the cause? If he hits it and it starts working then its a dry soldier.. other wise??

//perhaps a hundred bucks including opening and closing and testing. //

This could be why I never actually worked on fixing TV's as a living outside the classroom Programming pays you over rs 2000/hour... I had friends who charged over rs10000-20000/hour. And some of them were really cheap even at those prices.

[Biplav]

ok thanks guys
will ckeck out the lg service centre on monday

[Biplav]

nonsense lg walas didnt come 2 days after giving the complaint.
but i managed to get it back to work
opened the box and wiped 5 yrs of dust!!!that was tiresome
and found a aluminium plate and pushed it back to the main circuit hard.
that just did it.

[netcracker]

Great.this just shows how things can be solved if we don't depend on others