No Extra High Tension voltage from LOT. 115VDC supply output from power regulator drops considerably.
Suspected components are FBT [Fly Back Transformer], Horizontal output transistor, Deflection Yoke, Capacitors connected with Horizontal output section. Especially check the free wheeling capacitor/s connected to the collector of the horizontal output transitor to ground, for leak.
Desolder out horizontal output transistor [Q802 – 2SB1877], and check it. Check the junction resistance (collector to emitter) of this transistor. In no case, it should be measured Zero. There is an internal diode integrated with this transistor, connecting to its collector to emitter. So, when you measure the resistors between collector to emitter of this transistor, consider the forward bios conductance of this Freewheeling diode.
Replace the transistor with same type and number.
Switch ON the set after replacing this transistor. Switch On for a short period of time, say for 5 seconds or so. Switch the set Off and feel the heat of the replaced transistor by bare finger touch. It may be just warm, but not too hot. If it overheats, check the associate components. Suspect the FBT. If FBT has a short in between its internal EHT windings, even a single winding short in between, will place a tremendous load to the fly back output transistor (2SB1877), and it will overheat. If this is the case, there is no other way than replacing the FBT (NX-2821) with an other. In most cases, (90%), the fault will be with a shorted winding inside the FBT; which cannot be detected with a multimeter.
Before replacing the FBT with an other one, just check the 115VDC of the switching power output for its accuracy. Desolder out one end of resistor (R807 – 1.2 Ohms/2W). All these component numbers will be marked on both sides of the printed circuit board of this TV. Desolder out any one end of this resistor, will cause a supply brake to FBT. Connect a filament bulb (100 W), across (D608 – 120v Zener diode _ over voltage protection diode), and switch On the TV. Measure the voltage across this Zener diode. It should be between 113 to 117VDC. If not, power supply regulator section has some trouble and should be tracked. Never switch ON the TV without a constant steady B+ve 115VDC. It may cause more complicated troubles to the circuit.
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