I have a samsung tv model CT-15N30MJ, i always got a bad H-out transistor every time i replace it, provided yoke is good, have check the FBT and its good no leak as checked by a tech.
This is a common fault that everybody feels, when replacing the horizontal output transistor for Samsung CRT TVs. Samsung has provided no heat sink to this transistor, and generally, it wont't heat up abnormally. You should use the exact number of this transistor when replacing it. We can't get it from open market. Only authorized service center for Samsung can supply us its exact replacement. No more experiments should be done further, with any other number horizontal transistor. All of it work for a while, and will get shorted.
Gopakumar Gopalan Google
SOURCE: what causes the horizontal transistor to short?
Hello
You just replace the capacitor fitted very near to the horizontal output transistor,[freewheeling capacitor], there may be one or two of them, whcih comes to a value of 3900pf to 6700pf 2000V or so. It is connected to the negative rail and the collector of the horizontal output transitor. If it gets opened, or its value gets reduced, this fault will occur. If so the transistor you replace will get shorted as you swich on the power to TV.
The second one is deflection yoke short. If so the transistor said above will overheat within seconds. Even a single winding inside the horizontal deflection yoke shors, it puts a tremendous load to flyback transformer, which in turn effects the transistor.
After replacing the above said capacitor, you do one thing to make sure about whether there is a short inside the yoke or not. It cannot be measured by normal methods. Fore that, unplug the base card from picture tube and place it somewhere near without getting any of its contacts to other parts inside your TV. This time only the EHT chord will be connected to picture tube. Unplug the horizontal yoke connection from main board. Switch on the tv, and wait for some time, say at about 10 seconds, and check whether the transistor gets overheated or not If it does overheats now also, the winding or EHT retifier diodes inside your flyback transformer has some trouble, and it should be replaced with same type and number. If it does not overheats now, the deflection yoke's winding have some short in it. Ok.
NB: Never connect the TV with base card is in postion while deflection yoke connection is isolated. keep it unpluged.
as you can see in the image above is a digital tester some other brands may vary in ranges but all the function are the same. now set the pointer to the resistance checking select to the range with diode sign. a transistor have 3 pins for base, emitter and collector (component term ) with the use of test probe now touch one end of probe either of the 3 pins and other probe to the other pin.check the reading to the display of tester if no reaction reverse the polarity until you find the correct reading as what i said a good transistor is about .4 to.9 and then try this process to the other pin of transistor to check if all the junction are good.
the image above is sample of deflection yoke it was located and installed at the neck of ( crt )picture tube. if one of the coil winding has problem it always damaged horizontal output transistor and other part . i hope this trouble that i encountered will help you too to fix your problem good luck. 94 views
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