H Out; Overview; H Drive; Horizontal Centering - Sony TVP-08 Training Manual

Overview

The H out circuit is used to amplify the H Drive signal and deliver a current
signal, which will be applied to the Horizontal yokes. The signal applied to
the yokes will be a current sawtooth that pulls the CRT beams across the
screen at the Horizontal rate of 31.5 Khz. This circuit also uses T5002 to
create a DC offset voltage necessary to correct the tube angles where the
red and blue tubes are placed.

H Drive

The H Drive signal is input at CN5004/8 and applied to the base of Q5002.
Q5002 is a buffer signal that passes the H Drive signal to C5005. C5005
is a filter used to remove any DC component in the H Drive signal. The H
Drive signal is applied to the base of Q5008/B. This creates a signal at
Q5008/C, which is applied to T5001 HDT.
R5031 and C5019 is a snubber filter that is used to reduce any spikes on
the amplified HD signal. If there is a problem with these components, it
could cause the Q5013 H Out to heat up and fail. R5032 and R5026 are
fusible resistors designed to optimize the gain of Q5008 Horizontal Drive
Transistor. The signal developed across T5001 HDT primary windings is
coupled to its secondary, which feeds the H Out circuit.

H Out

When the H Drive pulse reaches Q5013/B, it causes current to flow in the
H yokes through the C-E junction of Q5013. This causes the CRTs beams
to go from the middle of the tube to the right hand side. When the pulse
goes LOW, D5009 Speed Up causes Q5013 H Out to shut off immedi-
ately. When Q5013 H Out shuts off, the magnetic field in the yokes col-
lapses and induces a voltage that will cause C5039 to charge. This causes
the beams to go from the right to the left side of the CRTs. When C5039
is fully charged, the magnetic field in the yokes will be dissipated, causing
C5039 to discharge through the yokes. The remaining current required
will flow through D5013 Damper. This will cause the beam to move to its
original position and the whole process begins again with the next H Drive
pulse.
H Out
79
The pin amp has an effect on the width of the picture since more current
is required to move the beam at the center of the tubes. The pin signal
modulates a vertical parabola signal onto the H Out signal. This causes
more current to flow through the yokes when the beam is towards the
center of the tube.
C5043, C5042 and C5041 form an AC Voltage Divider that is used to
reduce the level of the H out signal. The pulses created across C5038
are sent to the H pulse shaper circuit and used for the creation of the HP
pulse and to detect proper operation of the H Output by the H Protect.

Horizontal Centering

Since the red and blue tubes are not at 90-degree angles to the screen
like the green tube, we need to create an offset voltage. This is done by
applying the pulses from Q5013 H Out to T5002 HOT and rectifying these
pulses on the secondary side. The center tap of T5002 secondary is
connected to the return of the green yoke. One winding is connected
through PS5001, D5007 and R5008 to the return of the blue yoke. The
other winding is connected through PS5002, D5003 and R5007 to the
return of the red yoke. This configuration causes a positive offset voltage
across the red yoke relative to the green yoke, and a negative offset volt-
age across the blue yoke relative to green. This roughly centers the red
and blue tubes pictures with green.
Q5008/C
2V 20us
Q50013/C
100V 20us