Your TVs focus voltage has some trouble. You gets an out of focus piture now. There may be two reasons for this fault. The first one is, the focus pack trouble. The second one is picture tube base socket trouble. Both are repairable.
Focus pack is integrated with Line Output Transformer [LOT], and picture tube base socket is soldered directly to picture tube base card. You just open the TV and check whether there is any "Shhhh" sound comes from the neck side of the picture tube while tv is working. If it is so, you will get a smell of Ozone gas also. If it is so, switch off the set and unplug it from mains socket, pull out picture tube base card from the picture tube neck. Be gentle, and not make any shakes while pulling it out. The neck part of the picture tube is very thin relative to its other portions of the picture tube, and have a chance to break. So be carefull when you pull it out. You can see the base socket soldered directly to it. There will be two wires also, for some sets only one, attached to it. Normally the red wire going to a slot in the socket is focus wire, through which focus voltage reaches to the relative pin of the picture tube. Just detach the wire out from the socket, desolder it out and go for a similar type, and pin confuguration. Replacing it will solve your problem. After replacing the picture tube socket, a slight focus adjustment may be needed. Sometimes may not. The focus voltage can be adjusted. Its adjustment control is located on the above said [LOT]. There will be two adjustment controls, marked Focus and Screen. Out of which the upper one is for focus adjustment, and the lower one is for screen adjustment as its markings states. You just adjust the focus control very little, while watching the picture on your tv screen. Take menu display for reference, rather than moving pictures for focus adjustment, so that you will get a stationary image for reference.
The second stated trouble is related to the screen-focus pack integrated with the [LOT] itself. If it has got damaged, there is no other way than replacing the [LOT]. If so desolder it out from the circuit board, after detaching the anode cap from the top of the picture tube,and focus and screen wires. Before detaching the anode cap, care must be taken, as there may be some extra high tension voltage charge on the final anode of the picture tube, which is dangerous. You must discharge it before unpluging it, otherwise you may get electric shock from it, even after the Tv is switched off and unpluged from the wall socket. The charge may retain there for hours. So be careful.
If you have any more doubts, inform me through Fixya. Ok.
on Nov 05, 2010