output signal is provided at the base terminal 491 of npn transistor 463 which in conjunction with diode 462 and resistor 461 provides an output control signal at the base terminal of pnp transistor 459 the emitter terminal of pnp transistor 459 is coupled to terminal 424 which is the common blanking input terminal for all three channels as described above thus when the osd input signal received at terminal 489 of the pnp transistor 469 is held at a high voltage the current flowing in npn transistor 468 is increased so that voltage at terminal 491 drops resulting a decreased voltage at the base terminal of pnp transistor 459 pnp transistor 459 thus pulls the blanking input terminal to near ground voltage as a result pnp transistor 447 fig4 b pulls terminal 446 to near the ground reference thereby blanking output circuit 460 39 s input video signal an non inverting output signal corresponding to the osd signal at input terminal 489 is tapped from terminal 475 of emitter coupled amplifier 490 terminal 475 is biased to have a dc offset voltage determined by the voltage divider of resistors 482 and 486 plus the approximate 3 v be 39 voltage drop contributed by pnp transistors 487 488 and.