Pincushion Picture on a big TV screen!!!

Hello tj444,

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.

I hope this helps,

Thank you,

Shuttle83

http://www.electron-age-technologies-llc.com

Please let me know in which direction the picture is distorted. Does it bow in from the top and bottom or left and right?

Thanks,
Dan

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

If the picture is bowing in on the sides, this is called a pincushion problem. Please confirm that your model is KP-53XBR45 and I'll look up the probable defective parts.

Dan

Can you post a picture of what the screen looks like? It could be convergence amps or a pincushion problem. The pic would help clarify the diagnosis.

MY SONY DOES NOT DISPLAY NUMBERS ,VOLUME,MENU PANAL

too dangerous for a home repair as this requires replacement high voltage components and adjusting the set with the back off while running.
Take to repair store.

CHECK THE CAPACITOR IN THE PINCUSHION SECTION OF THE TV MAIN BOARD

Shannon you have a blue convergence failure. this problem can be repaired in home, by a good tv repair guy. John

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. Good luck.