Hitachi 51F510, Manual

Page: 77 / 152

DP-4X SIDE PINCUSHION CIRCUIT EXPLANATION
PAGE 05-09
(See the Side Pincushion Circuit Diagram for details)
Due to the nature of deflection, the sides of the picture has a tendencies to pull in similar to an hour glass. The
Side pincushion circuit is responsible for manipulating deflection to compensate. This is accomplished by super
imposing a vertical parabolic waveform on the DC voltage utilized for Horizontal Size.
VERTICAL YOKE CHARGE PULSE: (See Vertical Output Circuit for details related to this pulse)
The pulse generated on the positive side of
C607
is also routed through the parabolic wave form generation cir-
cuit of R616 and C606 . Then to the PDD1 connector pin 3 . Then to pin 6 of IB01 . This IC then generates a Ver-
tical Parabolic signal that is sent to the side pincushion circuit from pin 10 and a Vertical parabolic signal to the
Dynamic Focus circuit from pin 18 and out the PDD1 connector pin 1 for corrections to focus DC voltage.
SIDE PIN WAVE FORM GENERATION IC:
The Vertical parabolic signal from pin 10 of IB01 is routed through RB39 to pin 2 of IB02 . This is the negative
leg of the internal op-amp. Also attached to this input circuit is the Horizontal Size circuit comprised of a DC
level shift from pin
11 of IB01 to the base of QB05 . This manipulates the Collector voltage which is sent to the
same pin. The Microprocessor communicates with IB01 via I2C ( See the Microprocessor Data Communication
Circuit Diagram for I
2
C path ) and can adjust the DC level at pin 2 of IB02 . The output at pin 1 of the op-amp is
connected back to pin
2
via
RB33
for stability.
The output of the DC offset voltage with Vertical parabolic waveform from
I802 is output pin 1 , then to pin 6 . It
is then routed out pin
7
, out the
PPD1
connector pin
10
to the base of
Q703
. This transistor has its emitter off set
above ground by D713 , R704 and R747 back to the SW +10.5V . This transistor drives the base of the Side Pin
Cushion modulator transistor Q701 . The collector of Q701 is connected to the Deflection SW +115V. The hori-
zontal size DC offset voltage and Vertical parabolic side pin cushion compensation waveform is now super im-
posed on the SW +115V which is sent to the Deflection Transformer
T701
and the Horizontal Linearity circuit
C715 , L703 , R729 and R756 to the Horizontal Yoke returns.
D SIZE SWITCH:
When Magic Focus is activated by either the Magic Focus button or customer’s menu or during service when the
sensors are initialized, The Microprocessor
I004 receives the D Size signal from the Digital Convergence Unit,
UKDG pin 35 then to the PDS2 connector pin 7 . When the Microprocessor receives this signal at pin 43 , it
knows to increases the Vertical size to allow positive contact of the light pattern hitting the sensors. It does this
by I
2
C data communications to IB01 which then manipulates the DC offset voltage for H size via pin 11 and ma-
nipulates the Vertical Size via the V Drive signal output pin 4 . (See Vertical Output Circuit for details related to
Vertical Drive)