Technology of Q 2500 colour TV set

Technology of Q 2500 colour TV setsary to prevent this video pumping or at leastto reduce it. To do this beam current dependentcorrection information is applied to pins 4and 14 of the deflection controller . The OWand V amplitude are influenced via pin 4 andthe H phase via pin 14.The beam current dependent informationtaken from the base of the diode split transformerand output by W 1511 via resistancesand the two transistors Q 2639/Q 2638 is fedto pin 4 and pin 14 of TDA 9332. Switching viathese two transistors ensures that the basevoltage is adapted in an optimum way toI2521. pin 4/14 of I 2521 requires a voltagefrom 1.2 V to 2.8 V. The vertical amplitudecompensation is defined firmly in I 2521 and isthe same for all types of c.r.t. The horizontalamplitude compensation is influenced via internalregisters by I 2521. Various values areheld in EAROM for the various c.r.t types.Dependent on the measured values the picturewidth and, if necessary, the V amplitudeare influenced by the E/W output. Delay of thecontrol is about the duration of 10 lines. A lateralglitch at bright picture settings cannot beavoided but can be reduced to some extent.Due to the varying load on the line outputstage, the line flyback pulse is also affected.This means that beam current changes alsoinfluence the H phase. The correction informationon pin 14 of TDA 9332 opposes this viathe internal phase correction.Document Q 2500 109 © Loewe ProCollege