I am going to be replaceing the horizontal output transistor that was suggested and I am wondering if there are parts farther down the circuit that I could replace to prevent the 2sc4125 from blowing again. Thanks
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Re: Replacing horizontal output transistor
Many times, the only problem is hte transistor itself. There is really no way to determine whether or not additiona parts are required until the known defective one is replaced. If there are other symptoms once the transistor is replaced, post them here and we'll guide you to the defective parts.
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Hello Check the supply rail to LOT. If LOT [Line Output Transformer] is fauty, it will take tremendous current from the SMPS power supply output, and the overload sensor circuit will be energiised and the supply to the whole system will sut OFF. That is happening eith your TV now. Just desolder out the horizontal output transistor, the transistor that drives the LOT, and switch the set ON, and see whether it stays on or not. If stays on, check the collector to emitor resistoance of the horizontal output transistor. If there is any short with it, replace it and switch ON the set for a short time, say 5 seconds or so, and check whther the replaced transistor gets overheated. If it overheats, make sure that the LOT said above has damaged, and must be replaced with same type and number. If the fault is with the horizontal out put transistor, the set will work normally after replacing it. The components can be bought from local electronic spare part shops at your town. OK.
Try to replace new harizontal output transistor.Before replacing the transistor,check the regulator and the flyback if shorted or not.If the flyback is shorted the harizontal output transistor will be damage again if you trying to turn on again.Thanks..
Before replacing an other one, replace the freewheeling capacitor, the capcitor fitted between the collector of the 2222 and earth; usually of a value of 3500pf 2000VDC, some times this value may differ from set to set. If this capacitor has opened of developed in value, the result will be the failure of the horizontal output transistor, at switch ON itself. The second reason is the short in horizontal yoke windings. Even one winding get shorted, it will cause to a heavy load flyback transormer which in turn to 2222 failure. The last reason for this fault is defective Line Output Transformer itsef. Check these three.
Before proceeding, desolder out the horizontal output transistor 2222 fro circuit, and measure the frequency at the collector point of horizontal driver transistor. It should be around 15625HZ [may differ a little], with no signal. If this frequency is found higher than normal, The main IC jungle should be suspected.
Anyway, go forward after checking this frequency. OK.
As sound output is ok, main board is correct with respect to sound output, video IF and ther stages. The fault lies on the horizontal output section. It may be LOT fault. Check it further for horizontal oscillator stage, and horizontal output stage. Check the collector voltage at the horizontal driver transistor. If you have a frequency meter, check the frequency of that point. It should be somewhere near 15625Hz. If the frequency there is Ok, then proceed to horizontal output stage. Check the horizontal output transistor. If it seems to be faulty, replace it with similar type and number. If the replaced horizontal output transistor heats abnormally within seconds after swich on the set, surely LOT has troubel. Replace it also with same model mumber and type.
Check the voltage input to horizontal output transformer [LOT]. Check the voltage at the collector point of the line drive transistor. If the line drive transformer primary gets open this type of fault mau occur. Also check the frequency ant the collector point of line drive transistor and the base point of line output transistor. It should be aroung 15625 Hz.
Check and replace the horizontal output transistor if needy. Replacing it is better. The horizontal output is not working or a short in secondary power supply of SMPS or lot secondary, is your problem
When it is shifted to right vice versa, it indicates a distortion on the horizontal output. Try replacing all the capacitors around the horizontal output area with the same original value. Make sure the horizontal output transistors you replace hasn't started going gone bad already if you know how to check them. Them dimness in the picture is caused by the horizontal output not putting enough high voltage to the CRT. Look for leaking capacitors too. Also replace the resistors around the horizontal output, they may have burnt out or changed in value from overloading cause by the malfunction of the flyback, and the transistor.
The clicking sound, may be the shutdown circuit activating a kill relay. This is an indication that there is a problem in the HV section of your TV. This may be the horizontal output transistor or one of the other components in the HV section. I would suggest that you have a qualified TV technician examine the TV because the HV section is very dangerous and should be troubleshot and worked on by a person who is skilled in the area of TV repair. This problem may be as simple as replacing the Horizontal output transistor, however this task should only be done by a qualified TV technician.
The F27669 uses the CTC203 series chassis. The most common cause of that symptom is a shorted horizontal output transistor, caused by a cracked solder joint on a small coil connected to that transistor's base. When this happens, the main B+ supply is shorted to ground so the power supply squeels. Every once in a while I also see the horizontal output transistor shorted due to a shorted flyback (high voltage) transformer. A good tech will replace the horizontal output transistor, resolder the coil and drive transformer, test the flyback (replacing it if necessary) and your set will be back to perfect.