Technology of Q 2500 colour TV set

Technology of Q 2500 colour TV set2.6 Vertical output stageIn comparison with earlier models the Q 2500generation of chassis does not have an a.c.coupled, but a d.c coupled vertical outputstage. This has the advantage that the verticaldeflection coils can be supplied with currentdirectly and the large coupling capacitor canbe dispensed with. This means that verticalcorrection information can operate directly,without vertical distortions caused by the deflectioncoil coupling capacitor.As we know, a positive and a negative deflectioncurrent flow through the vertical deflectioncoils. In order for the d.c. coupled output stageto produce this negative current, it must besupplied with a +/- voltage.The two possible variants of the vertical outputstage IC´s (TDA 8177/STV9379FA) incorporatedinto the 100 Hz Q 2500 chassisare housed in a Heptawatt plastic housing.The following functional groups are incorporatedinto the IC´s as circuit components:• A power operational amplifier that is able todrive the vertical deflection coils with apeak deflection current up to 3 Ass.• A flyback generator, that generates thevoltage charge for the vertical flyback.• A temperature protection circuit that limitsthe deflection current on overload.The power operational amplifier is controlledsymmetrically and inversely on its noninvertingand inverting inputs. Therefore, thevideo/deflection processor outputs two inverselysymmetrical vertical control signals.Vertical output stageV+ VÐV-FlybackR566R578W 511Pin 1VPROTW 511Pin 4R563C564C563C567R565C579 R579 C578R573D561UV+16VUV--13V246 3 7I 561FlybackGeneratorTDA 8177/STV9379A1-+5R564R567R569VerticaldeflectioncoilsTemperatureprotection circuitR574R568C568Document Q 2500 28 © Loewe ProCollege