Panasonic EURO 4 Chassis, Technical Manual

Page: 17 / 163

3DQDVRQLF
17
9. HORIZONTAL/VERTICAL OUTPUTS
9.1. Horizontal Driver
The line frequency control pulses for the horizontal
driver stage are output via pin 50 of the VDP
IC601
at 1v pp and fed via C508 to the base of transistor
Q503 .
Diode D501 permits rapid discharge of capacitor
C508 in the blocking phase of
Q503 .
From the circuitry of the line buffer stage, as well as
from the driver of the line output stage, it can be
clearly seen that this is low impedance current
control. The driver stage is fitted with a transistor
which is able to supply the necessary base control
current of up to 0.9 Amps for the driver transformer
T501 of the output stage.
To limit the inductive breaking peaks during the
blocking phase, the RC. combination R509, R510,
C511 are connected in parallel to the primary
winding of T501.
The driver stage operates in alternating mode in
relation to the output stage, i.e. when
Q503 is
rendered conductive. Q551 is off and vice versa.