Question about Sony KV-29FX66 29" TV

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Pincushion Picture My TV set had suddenly started to project a "pincushion" (concave sides) picture. The TV laboratory claims that the Flyback transformer and other parts should be replaced. My impression is that the lab estimation is exaggerated since, as far as I understand, when the Flyback fails, there is no HV supply to the CRT and there should be no picture at all. Please advise.

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Re: Pincushion Picture

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.

Posted on Sep 18, 2006

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Occasionally the picture snaps into what looks like a pincushion.

it is infact pincushioning.. these tv's have a maze of boards.. try to contact manufactuer about pincushion pcb also try to auto converge colours if you can.

Dec 14, 2009 | Mitsubishi WS-55807 TV

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I need to find the pincushion circuit on my RCA F32632SB TV to check a problem with the TV displaying an hour glass picture. Where can I find a picture of this or a manual to guide me to the circuit?

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

Jan 15, 2009 | RCA F32632SB 32" TV

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Apex PF3230 TV with pincushion problem.

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.

Nov 08, 2007 | Apex Digital PF3230 32" TV

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Is there an adjustment for pincushion?


Oct 25, 2007 | Standard (CRT) Televisions

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The picture on my projection TV has intermittent concave right and left sides. Can you tell me what's wrong with it? your problem is due to pincushion ckt as it is intermittent so that there might loose contact or print break in pincushion ckt it can be rectified easily by skilled tech. there is no parts failure. good luck

Sep 23, 2007 | Zenith Z56Z83R/D TV

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Pincushion Problems

check the cap that couple the horizontal transistor, this could be bad replace the flyback.all caps and transistors in that circuit should be cheked.good luck.

Apr 03, 2007 | Proscan PS27108 TV

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Pincushion issue

Both transistors have built in damper diodes that are designed to work in "flyback" circuits, and the 2SD2645 is rated to handle 15 more watts and 2 amps more current than the 2SD2634, so I suspect the technican felt that the replacement part would be less likely to go bad. Of course if they subbed the transistor, could the flyback also be a substitute? Sometimes faulty capacitors in the collector circuit of the Horizontal output transistor can cause timing problems that also cause the transistor to fail. If that is the case, then further troubleshooting is required to find and replace said capacitor(s), and that could also be the root of your problem. There is also one other possibility I can think of (aha!) and that is that the 2SD2645 was a "off brand generic" that does not live up to its published specifications. With Sony products, I have learned (the hard way sometimes) that it is usually best to use only OEM parts.

Jan 02, 2007 | Sony FD Trinitron WEGA KV-27FS200 27" TV

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Pincushion problem

My thoughts would be, was it a Sony OEM transformer or a generic type? If the latter, that is probably a likely suspect. Another thing would be misplaced wires or switches that could have been accidently moved while replacing the transformer. I have had some of these sets that had no high voltage, and all it turned out to be was a broken solder connection on one of the pins going to the flyback transformer. Usually, if the flyback is bad, the Horizontal output transistor would be also defective. It's also possible that in the process of removing the old flyback (fun job wasn't it?) you may have cracked one or more of the circuit traces in that area of the PC board.

Jan 01, 2007 | Sony FD Trinitron WEGA KV-27FS200 27" TV

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Shrinked picture of 29 inch television.

It is a pincushion problem. There is a bad cap and or a bad diode in the horzontal section.

Oct 29, 2006 | Toshiba 27A51 27" TV

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