Hitachi 61HDX98B Manual page 18

BLOCK DIAGRAM EXPLANATION DEFLECTION BLOCK
is superimposed upon the static focus voltage to com-
pensate for beam shape abnormalities which occur on
the outside edges of the screen because the beam has
to travel further to those locations.
HV PARABOLA:
Described above.
SCREEN 700V: 700V Supplied to the screen grids on
the CRT's.
FOCUS 9KV:
Focus voltage supplied to the CRT's.
32Kv HV:
32,000 volts DC supplied to the CRT's anodes.
TO DEFLECTION YOKES:
Horizontal and Vertical deflection wave forms driving
the deflection yokes.
INTERNAL BLOCKS DESCRIPTION
HV CONTROL:
The uPc1344C IC generates the horizontal drive signal
utilized by the High Voltage circuit. The HV control
IC receives it's locking pulse from the Deflection cir-
cuit. A feed back voltage is sampled from the High
Voltage Regulation Detector circuit and compared
with a reference voltage to maintain an accurate 32KV
on the CRT's.
VERTICAL OUTPUT:
The vertical output utilized in the 61HDX98B operates
differently from previous chassis. This circuit utilizes
a +13V and a –13V to generate the waveform to drive
the vertical deflection yokes. A pump up circuit is util-
ized to product the retrace pulse for the vertical deflec-
tion yoke. It's at this time when a higher pulse is
needed because the beam has to travel from the bottom
of the screen to the top very rapidly. The vertical out-
put IC receives it's trigger pulse from the ramp gen-
erator.
SYNC PROCESSOR:
The Sync Processor located in I702 on the Sub Deflec-
tion PWB, detects the horizontal sync rate for the dis-
played signal, either 480P or 1080I.
VERTICAL RAMP GENERATOR:
I702 on the Sub Deflection PWB generates the Verti-
cal Saw signal. This signal is controlled by several
factors. The Sync Processor detection and I2C data
communication.
DIST CONTROL:
Distortion control is another signal produce by I702
and sent to the Side Pin cushion circuit. These com-
pensation parabolic wave forms are combined with the
horizontal circuit to compensate for Side pincushion
errors.
H-SIZE SIDE-PIN CONTROL:
This circuit generates the Side Pincushion Distortion
compensation pulse which is impressed onto a coil
located in the output side of the Deflection Output sec-
tion and compensates for Pin Cushion distortion.
HORZ. DRIVE and HORZ. OUT:
This circuit comprises the Drive and Output for the
Deflection output circuit.
S-CORRECT (SMOOTH MODE):
During Smooth mode, the deflection circuit is manipu-
lated so that the outside 1/3 of the picture is stretched
to fill the screen. The center 2/3 of the picture is left
undistorted. When an S Wide signal is received, a ca-
pacitor is switched off on the output side of the De-
flection output circuit.
PHOTO SENSOR:
There are 8 sensors located on the internal outside
edges of the cabinet. These Photo Cells receive the
light patterns being generated during MAGIC FOCUS
or SENSOR INITIALIZATION and deliver this volt-
age to the Sensor Distribution circuit.
SENSOR DISTRIBUTION:
This represents the amplifiers that receive the Photo
receivers (Photo Cells) inputs during Magic Focus op-
eration.
DIGITAL CONV. UNIT:
This is the Digital Convergence Unit. This is a non-
repairable unit. It contains the distortion compensation
wave form generation circuits, RAM, ROM and D/A's
for the convergence circuit.
SERVICE SWITCH:
When the set needs a convergence alignment, the Ser-
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