Hi...my LG's 29" TV firstly got no power, but after changed a new flyback transformer, the TV already turn on but facing a new problem. That was no display at all..the picture and sound was in a good condition. But if i turn the volume or channel button up and down, the TV function but no indicator(display) on screen...could you please help me? is that my system ic was in trouble? which component control the display for volume, channel, all function menu etc...?
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Re: got picture but no display...
Yes it could be the microprocessor IC or the display IC. Im not sure how the display system works as I do not have a schematic for the set. now what I have seen in the past, is that when the flyback blew out it sent a spike pulse way bigger then it should have been and blew out the display sync circuit, and that is built into the microprocessor. Also I have seen in the past, when a main componet such as a flyback transformer is replaced, there are small surface mounted componets near and around the flyback that gets unsoldered. These are ussually small surface mounted type resistors or capacitors that send a pulse to sync up the display output with the horizontal and vertical sweep, or the display would not know where to be and would run so fast along the screen that you would not see it. Check out the horizontal pulses to the micro, or like I said the micro is bad. Good Luck
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replace flyback transformer ( same type ------------ equivalent will not work ) & also resolder most of the soldering joints on mainboard & CRT circuit board (small circuit board fixed to tube) ------- 100% it works normally --------- after fixing flyback transformer --- switch on tv and then adjust its knobs according to brightness & clarity of the picture...............only technical people should do this .............. if non technical persons try to do this then there are chances of getting electric shock ..........
Sounds like it has an intermittant connection somewhere which is very
common now a days due to the lead-free solder all the makers went
to. Resolder everything that looks suspicious, especially the
bigger components. It could also be a failure of the flyback
transformer though which often times fail like this.
Hope Ya Fix It.
The horizontal output transitor is always connected to the primary winding of the flyback transformer (via collector) and also to the horizontal deflection coil via an electrolytic capacitor.
The most likely suspect for damaging the transistor is the fylback transformer. In some countries there are electronic stores that test flyback transformer by winding a few turns on the ferrite core and applying a test voltage. This test will only test the secondary.
The primary winding is difficult to test for turn to turn short because the resistance is quite low and you do not know the 'good' resistance.