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Re: my tv sound ok, crt high voltage ok,channel number...
Check for a resistor rated around 220kohms somewhere around the flyback area. i have never worked on this model tv before so i cant give you an exact part number on the board but had the same problem with sharp tvs
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Check and replace damaged component/s at its horizontal scan output section circuit. Check the LOT (Line Output Transformer) too for damage. Replace the horizontal scan output transistor. Check the input voltage to LOT. If the voltage is absent check the feeder resistor; if any. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/
This sounds like a high voltage problem or a picture tube issue (burnt out filament). I would first determine if you had high voltage at the anode of the TV by using a high voltage probe. If you do not have high voltage then I would suspect the voltage doubler, the IHVT (Integrated High Voltage Transformer) or the Horizontal Output Transistor (I doubt this only because you don't have a power supply failure and I would expect this in a modern TV since the high voltage supply is tied to the low voltage supply), the more likely suspect is the voltage doubler. Second possibility I would check is the CRT socket board and CRT filament. Unplug the TV and with a multimeter set to read resistance check to see if the filament pins read a low resistance if so the filament is good. Plug the TV back in and turn it on and check the voltage on the CRT board and compare them to the schematic values. These two tests should localize the issue. Now, If you have a background in electronics, this should be no problem to do, however if you do not have a background in electronics, I would suggest that you have a qualified TV technician troubleshoot and repair this TV set.
I posted this earlier, however I believe it applies in this case to:
This can be any number of things, here is a possible listing:
1) No High Voltage (check the IHVT or the trippler)
2) CRT filament transformer winding open (check the windings that supply voltage to the CRT filaments)
3) Video / CRT socket boards bad (highly unlikely but check anyway)
4) High Voltage power supply malfunctioning (related to problem #1)
listing is a good starting point. I would suggest that you purchase a
schematic to aid in testing the voltages mentioned in the 4 steps
above. If you have a background in electronics then do the above, if
not please ask a qualified TV technician to perform these steps.
This is not something that you can fix, the sound is the high voltage section with the horizontal output transformer. The reason is a possible flyback transformer failure or the high voltage diode is bad. Most electronic shops can fix it.
maybe you have defective heater line tru the CRT board! check the
heater line if have a 4.5 volts or 4.8 volts! can you see the back of
picture tube!?! they lights coming out at the neck of the tube! if no
light! you have defective heater supply!
Sounds like you have lost video somewhere in the video circuits. Possibly the picture tube could have gone bad or lost filiament voltage.
You can check to see if you have high voltage by holding your bare arm close to the screen. The hairs will stand up if you have high voltage. Absence of high voltage will also cause a black screen,but the sound might not work either since on some sets the power for the sound is supplied from the same circuit as
the high voltage.