Horizontal Deflection Block - Sony WEGA KV27FV15 Training Manual

Direct view television circuit description and troubleshooting

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Horizontal Deflection Block

Overview

The horizontal deflection block creates the signal that drives the horizon-

tal yoke and also drives the flyback transformer to create the necessary

high voltage, focus voltage and other voltages used by the set.

The HD signal originates from the Y/C/J. The HD signal is applied to the

amplifiers in the H drive and H Out circuits. The signal that exits the H Out

transistor is applied to the flyback transformer and the deflection yoke.

The deflection yoke uses magnetic fields formed by the current through it

to drive the beam across the screen. Feedback from the yoke is coupled

to the centering and linearity circuits. This circuit ensures that the picture

will be linear and centered properly. These circuits work in conjunction

with the pin amp on the return to the H Out.

The purpose of the pincushion circuit is to correct for deflection distortion,

which occurs because of the yoke's inability to create a linear beam scan.

The result would be a picture bowed at the sides. We compensate for this

problem by using pincushion correction circuits to control the amount of

current that can flow through the horizontal output's return.

More current is delivered so the beam can be pushed to the sides of the

tube when necessary. The drive for the Pin amp is created in the Y/C/J

and is called E/W drive. It is applied to the Pin amp with a sample of the

HP pulse. Q512 controls the current through the H Out return.

A protection circuit also monitors the HP signal. This protection circuit

allows HP signals to pass to the Y/C/J if the Pin amp and H Out circuits

are operating normally. In the event of a failure, the HP/Hoff line to the Y/

C/J would go LOW. The Y/C/J would then disable HD, which would cause

high voltage to be lost.

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