A straight horizontal line across the center of the screen denotes the full failure of vartical sweep in your tv. There is two main reasons for this. The first one is vertical output Ic and any of its related parts inside the printed circuit board of your tv is faulty. The second one is deflection yoke [the coil fitted alongwith at the neck of the picture tube] is open. The second fault said here is very rare. The fist one is reported more.
There may be, as said earlier, the IC [Integrated Circuit], may be faulty. You just locate the vertical output Ic inside your TV. normally in most televisions, it will be screwed into a heatsink metal, as it will be get heated during operation, the metal conducts the heat gereated by this Ic to the surroundings, to make it at a constant safe temperature. In most cases, we have seen, this Ic may opend. That is its inside drive integrations got faulty. It has a particular number marked on it. You must note that number and replace it with a similar type and number.
You just open the back cover of your tv, while it has been isolated from the mains supply, by unpluging it from the wall socket. There are four wires run to the deflection yoke (stated earlier), amoung, two of them will be thicker than the other two. Catch up the other two thinner wires, and look from where it is connected to the main board. You can see very near to this connection, an Ic fitted into a heat sink screwed. That is the Ic in suspect.
With set open, supply it and wait for 5 minutes or so, and unplug the tv from wall socket, and touch the heatsink of that ic gently, and see whether it overheats or not. Some amount of heat will be there, but it should not be overheated. If overheat is there, the Ic has damaged. Replacing it is the only remedy.
Another possibility is, the said Ic doesn't get the proper supply voltage to it to work. To find this, you should have a multimeter in hand, and the ability to find out the points I am going to report. Refer to the schematic diagram of your TV [not the manual, It gan be get from electronic book shops], and find out the main supply point of that Ic. It is a hot check, that is you only can check it with your tvs printed circut board pulled out, and the tv is switched on. Every precaution against electric shock shuld be taken before that. Keep children away from you, and let an adult beside you.
If the main supply voltage is correct, it may be around 35VDC or so, check the voltage of its output pin. It should be neare to 1/2 of the main voltage. If ther is exess votage shown, or no voltage at all, surely the said Ic is faulty. Replacing it will solve the problem.
Find any difficulty, report it to Fixya. They will give alert yo me. Ok.
on Oct 21, 2010