Horizontal output transistor keeps failing

The horizontal output transitor is always connected to the primary winding of the flyback transformer (via collector) and also to the horizontal deflection coil via an electrolytic capacitor.

The most likely suspect for damaging the transistor is the fylback transformer. In some countries there are electronic stores that test flyback transformer by winding a few turns on the ferrite core and applying a test voltage. This test will only test the secondary.

The primary winding is difficult to test for turn to turn short because the resistance is quite low and you do not know the 'good' resistance.

Replaced your horizontal output transistor D5072 and this solve your problem.

What do u mean by LOT ( EHT ), in this problem, the main 200v supply intended for the horizontal output transistor wud passed thru a MOSFET, The gate was connected to the output of an IC that determines the presence of signal from a computer. The MOSFET would reduce this voltage to 165v for the hor transistor. now the presence of signal from computer would change the LED from orange to green, but the 200V did not passed to the hor transistor, the MOSFET was not turned on. One thing i've noticed was if i remove the hor out transistor, the MOSFET would turn on. This MOSFET will reduce the 200v to 165v so i could not try shorting it when the hor out transistor is soldered. i've already change shorted 0.22mf capacitor in the flyback transformer that i thought was the cause and the 2.2uf/50v capacitor blown before. please explain to me what u mean LOT.

my tv is daewo 29 inch. help me what kind of horizontal out we are to replace cause its always damage in minutes.tyvm

replace the LOT (eht) transformer and than put the new horizantal transistor than switch on and monitor will b displays ok