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Re: Need to locate the pincushion circuit on RCA F32632SB...
Ok this might help rca labels their circuits this way..
1000 the tv processor
1100 remote receiver
1200 audio IF
1400 a/v hifi outputs
1500 s-video inputs
1700 stereo audio demodulator
1900 audio output
2300 video IF
2400 sync separator
2700 luminance processor
2900 rgb bias and drive
3100 system control
3300 analog interface
3400 front panel assembly
3600 tuner control
4000 ac input
4100 b+ regulator
4300 horizontal osc.
4400 horizontal output
4500 vert deflection
4600 standby regulator
4700 secondary power supplies
4800 pincushion correction
4900 x-ray protection
5000 kine driver
7500 fm radio
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This is a loss of the "pincushion correction" circuit. These sets are known for bad high voltage capacitors in the horizontal circuit that cause a loss of pincushion correction. It could also be loose solder connections in the horizontal circuit. This can be a dangerous circuit to work with. Have a shop check it for you. Thanks for using fixya.
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
I looked up this model and found the following electolytic capacitors to be the most likely culprits within the pincushion circuit. Check these first. The starred one is the one I have replaced in the past to resolve this.
Sorry Ginko, but a convergence problem would have the curves down from the top and up from the bottom. The hourglass shape is a pincushion problem. This can be as simple as a bad capacitor in the pincushion circuit.
Could you please confirm the model number so I can look up the probable part?
I am sorry that its took so long for me to reply been backed up in shop, anyway what you have is bad solder joints on large Diodes Resolder ends on all of them and this should slove your problem if you havent done so by now.