Philips 7629, Service Manual

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energy is available for excitation through C2465 and the line deflection. As a
consequence the flyback pulse is less distorted.
The S-Correction
Since the sides of the picture are further away from the point of deflection than from the
centre, a linear sawtooth current would result in a non-linear image being scanned (the
center would be scanned slower than the sides). For the center-horizontal line, the
difference in relation of the distances is larger then those for the top and bottom lines.
An S-shaped current will have to be superimposed onto the sawtooth current. This
correction is called finger-length correction or S-correction.
C2456//2457 is relatively small, as a result of which the sawtooth current will generate a
parabolic voltage with negative voltage peaks. Left and right, the voltage across the
deflection coil decreases, and the deflection will slowdown; in the center, the voltage
increases and deflection is faster. The larger the picture width, the higher the deflection
current throughC2456//2457. The current also results in a parabolic voltage across
C2484//2469, resulting in the finger length correction proportionally increasing with the
picture width. The east/west drive signal will ensure the largest picture width in the
center of the frame. Here the largest correction is applied.
East/West correction
In the T8, there are three types of CRTs, namely the 100º, 110º and wide screen CRTs.
The 100º CRT is raster-correction-free and does not need East/West correction.
The 110º 4:3 CRT comes with East/West correction and East/West protection.
The wide screen TV sets have all the correction of the110 4:3 CRT and also have
additional picture format like the 4:3format, 16:9, 14:9, 16:9 zoom, subtitle zoom and the
Super-Wide picture format