Philips 7603 series, Руководство по обслуживанию

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East/West correction
In the M8, 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 110º4:3 CRT comes with East/West correction and East/West protection.
The wide screen TV sets have all the correction of the 110 4:3 CRT and also have additional picture format like the 4:3
format, 16:9, 14:9, 16:9 zoom, subtitle zoom and the Super- Wide picture format A line, written at the upper- or lower side of
the screen, will be larger at the screen center when a fixed deflection current is used. Therefore the amplitude of the
defelection current must be increased when the spot approaches the center of the screen. This is called the East/West or
pincushion correction.
The 'Ewdrive' signal from pin 15 of IC 7200 takes care for the correct correction. It drives FET 7400. It also corrects
breathing of the picture, due to beam current variations (the EHT varies dependent of the beam current). This correction is
derived from the 'EHTinformation' line.
Two protections are built-in for the E/W circuit: over-current and over-voltage protection. See Luminance / Chrominance
signal processing .
Panorama
The panorama function is only used in 16:9 sets. This is a function to enable the 4:3 and Super-Wide feature. It drives the
'Bass_panorama' line, to activate relay 1400. When this relay is switched on, the capacitors 2453//2454 are added in parallel
to the default S-correction capacitors 2456//2457.
This results in an increased capacitance, a lower resonance frequency of the line deflection coil and the S-correction
capacitors and therefore a less steep S-corrected line deflection current.