I have a sony (KP57WS500)57" big screen TV.
I have a pincushion pictures on my green beams and on the red and blue beams the pictures looks perfectly find. When the problem first started was a double line or double images on my screen, so I reset the Tv colors and flash focus(converge) that didn't help, so I took the tv back cover off and check the CRT beams and all of them are function than I cover the red and blue beams with a card board and I notice the green beams pictures are not straight at all. It looks like a bow(pincushion) on the top and bottom of the screen. When I checked on the blue and red beams the pictures are perfectly straight. Does any body know where to adjust this pincushion pictures or have any clue whats wrong with it? Any advice will help-Thanks....
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Re: Pincushion Picture on a big TV screen!!!
The set has 3 IC's(one for each color)strictly dedicated for the aligment of each color,if one them does not align is because is going bad or is already bad becuase picture can not be adjusted,the IC's can be identify because they are mounted on a heat sink and have the markings STK--- ---,they are all the same and need to be replaced with an exact replacement.If you are familiar with tv service you can replace them,sometimes the new ones need to be aligned from the service menu,you will need the service manual,soldering and unsoldering will be involved,If you are not too familiar be safe and seek the assistance of a servicer.
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This is not a picture tube problem. This could be what is called pincushion distortion. It is caused when the is a malfunction in the deflection coils and the inability to correct for the curvatures caused by the CRT. The pincushion distortion can also be caused by the degradation of the functionality of the convergence amplifiers in the TV set. I would suggest that you have a TV technician examine the deflection circuitry and the pincushion circuit, this would also include the convergence amplifiers.
The pincushion it intimately related to the horizontal circuits,the electron beam must travel farther to reach the corners of the crt and it does to the middle and so without pincushion circuits the raster would be bowed in on the sides on crts 27 inches are larger.Pincushion corrections straightens the raster by modulating the horizontal yoke current at a vertical rate.In an RCA tv the pincushion circuits are usually numbered 4800and the pin amp will probably be numbered 4801,its drive transistor should be Q4802,R4802 will be the width control,and R4805 the e/w pin amplitude. its inputs from the vertical should be Q4801 (subtractor) Q4803 (buffer) you should have a parabola waveform at 4801,yoke current can be modulated here without effecting high voltage.when Q4802 conducts voltage should decrease across Q4801 and the voltage drop across the yoke increases. The east west pin amp control 4805 controls how much of the vertical parabola is input to U4801 to compensate for changes in width caused by variations in beam current.By varying the e/w control resistor you can know if the circuit fault is in the input or output,if the picture varies in size the fault is in the input to U4801,if it does not vary check the output or U4801......hope that helps
Lets try something before you call for a second opinion,with the tv ON and the problem showing hit the top and side of the tv,if the picture somehow reacts or corrects itself when you hit it call someone else and tell them what the problem is and that you feel it has a loose conection,dont have to tell them about the first estimate.
Dont hit the tv with a hammer,just with the palm of your hand.Is worth the try.