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Re: Hit by lighing
Check the fet Q502 (2SK3326), Ic504 the opto-isolator (PC817), and D517 for leakage. Use a dmm with diode testing - test froward then reverse, if you get any sustained readings both ways replace it with an NTE552. Also check R510 100 ohm....
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just read the model and then google it, beside, if you short them, you need to replace them with same value, and this will be determined by the circuit, if you did not change the circuit - just buy two new diodes and install them, do not bother with voltages as they have some tolerance and type will determine it.
The fuse may have failed. However, since you mention smelling something burning, you'll need to check if other parts (for example: a resistor or diode) also was damaged. That burning smell suggests that you had a short in the circuit and high voltage got past the fuse. If you insist on fixing the TV, you will need to identify any short and fix that before attempting to use it again.
I hope this helps.
(I've dealt with several resistor fires over the years. Sometimes the resistor or Zener diode is actually the fuse for the circuit. That simplifies the solution.)
Please check the horizontal output transistor for leak, base-emitter. Change it.If there is any kind of short in the board, the power supply will sense int and will shuts down. Line out put transformer [LOT] may also suspect. On the secondary supply stage from LOT, the secondary power supply section, check all the rectifier diodes, and its filter capacitors for leak. Even a slight leak will effect the proper function of the set. Check it with good qulaity analongue multimeter, with setting it to meg ohms range; check the suspected componets off board. Likewise check the primary rectified DC voltage at SMPS stage. It should be aroung 380V DC accross main filter capacitor. If it is not check the main filter capacitor [usually 330Mfd 450V] for low capacity. and check the four main rectifier diodes.
mostly this problem cause opto coupler is short. change the opto coupler and related parts like transistors,zener diode.and check all diodes&capacitors is power supply. you find any leaky or damaged part change it. thank you
Check the power supply transformer primary driver transistor and the associated components (some diodes and capacitors, resistors, an optocoupler maybe) and the rectifier diodes (or a bridge) and capacitors at the transformer secondary, what you are looking for is a short circuit, however, the short may as well be in another section of the circuit board (a shorted component may sometimes have signs of damage caused by heat, but this is not a rule).
This problem is caused by a shorted Horizontal Output Transistor. I would suggest that you have this TV checked by a qualified TV technician. This type of problem requires dealing with dangerous voltages, and repair should only be attempted by a trained technician.
If the regulator is being shorted right after you replace it, I would say that you have a polarized part that is doing that. I would suggest to check all the diodes and capacitors around the power supply circuitry, There is a posibility that T601 is shorted internally, also check IC603 for s shorted condition..
Check this picture for the power supply schematic.
The red line on ICS is quite normal it does not mean the part has failed.
To be honest in most cases if a tv has been hit by strike it is a right off & scapped.
What I suggest is to remove the main pcb & power supply pcb if its seperate & inspect the print side of pcb for signs of arcing tracking or burnt track. Repair any damaged track by cleaning off the coating to get at clean copper then solder wire accros to bridge the damage.
Check the power supply resistors diodes transistors look carefully for any burnt components or components which are physicaly damaged.
Check the line output transistor this will be near the large transformer with a thick red ht lead going up to the crt.
Check all the components you can in the line stage look at all the ICS to ensure none of them have holes in them or have blown apart.
Hopefully you find some or one if your very lucky that is damaged replace it & try your tv.
Could it be in the HV circuit?
first you isolate h/output section from power supply.
make power supply output ok.
check h/output section for short circuit
1 print short near eht
2 diodes or cap.near eht
3 yoke H winding just by removing connector
4 EHT transformer