Philips 29PT6441/85, Service Manual

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Tilt and Rotation
The rotation control signal is a PWM output from the UOC. It is filtered by R3252,
R3246, R3259 and C2259. The DC voltage after filtering at C2259 will be amplified by
R3245 (Main Board) and R3390 (CRT panel).
The output stage functions similarly as in M8/L01.1 with rotation IC TDA8941P.
TS7331/TS7382 and TS7332/TS7381 will function alternatively corresponding to the
rotation setting.
CRT panel
The RGB amplifier stage is exactly the same as in M8/L01.1. However, the RGB
amplifier IC has been changed to TDA6107AJF or TDA6108AJF. The “A” indication is
with gain of “80” rather than “50” in M8/L01.1. The diode D6332 used in the former
chassis, to solve the bright screen during start up, is not required because this IC has
the error correction implemented.
Scavem
In certain versions, the Scavem feature is used to enhance the sharpness of the picture.
The RGB signals are first differentiated and subsequently amplified before feeding to an
auxiliary coil known as the SVM coil. The current, flowing through the SVM coil during
the picture intensity transients, modulates the deflection field and thus the scan velocity.
During the first half of the intensity increase, the scan velocity is increased (thus
decreasing the current density by spreading it on a wider area). During the second half
of the intensity increase, the scan velocity is decreased (increasing the current density
by concentrating it on a smaller area). The increasing current density transition is
sharpened. A decreasing current density transition is processed in a similar way and is
also sharpened.