Circuit Description
GB 83
A10PTV2.0 NTSC
9.
9.
Circuit Description
The A10 PTV chassis is designed for release in the 2000-
2001 model year. This product is scheduled for release in the
NAFTA and Asia Pacific regions. The set is built in three
screen sizes, 43 inch (109 cm), 50 inch (127 cm), and 55 inch
(140 cm). These sets are capable of receiving signals in the
PAL/D, PAL/I, PAL/BG, NTSC, or NTSC/M formats
depending on the package for a particular country. The set
is equipped with a two tuner PIP. The set has three
composite Video inputs, two on the Rear Jack Panel and one
on the Side Jack Panel. The set also has two SVHS inputs,
and one component input. A Center Channel Input on the set
allows the speakers in the set to be used as a center channel.
The MG99 Projection TV uses three single color tubes, Red,
Green, and Blue. The output of each tube is projected onto a
mirror where it is then reflected onto a viewing screen. The
Tubes are converged so the light from each tube strikes the
same spot on the Fresnel Lens. The Fresnel Lens equalizes
and Concentrates the light to provide equal light uniformity
across the screen. The Mirror is a first surface mirror type,
which has the reflective coating on the outside of the mirror.
To prevent scratching of this surface, always use a soft
cotton cloth to clean it.
The Lenticular Lens Screen calumniates the light from the
Fresnel Lens. The Lenticular Lens increases contrast by
reducing the ambient light by the use of Black Striping. The
Prismatic formation of the screen allows for nearly 3X light
output as compared to a flat screen. Caution should be used
when working with the screen. Damage can easily occur in
the form of scratching, or by using certain chemical screen
cleaners which can strip the black striping from the screen.
The clean the screen, use one drop of dish washing
detergent in a small bowl of water. (Approximately 2 liters)
Wipe the screen with a soft cotton cloth in the direction of the
stripes.
The Three CRT’s are driven by 30KV of high voltage and
15KV of focus voltage. The Tube produces a highly
concentrated light output of color. A liquid coolant of Glycol
is used to transfer heat from the face of the tube to the
surrounding mechanical assembly. The C-element lens
seals the Coupling fluid within the coupler. The C-element
lens and Coupling fluid are part of the light path and
contribute to the properties of the optical system.
9.1
Power Supply
9.1.1
Power Supply Block
AC Mains are fed to the PFC (Power Factor Correction) or
Line Conditioner. The output of this panel is fed to the
Standby and Full Power sections, which are located on the
Large Signal panel. The AC mains voltage is 230 volts for
sets with the Power Factor Correction circuit. The ac Mains
voltage can be either 115 or 230 volts for the multi-voltage
sets. There are two dc output voltages from this panel, which
are 160 to 325 volts dc to the Standby Power section on the
Large Signal panel and 160 to 380 volts dc to the Full Power
Section. The 160 volts dc is present is the AC Mains are 115
volts. The 325 volts dc is present if the AC Mains are 230
volts. If the Power Factor Correction circuit is present, 380
volts dc is present. If the Power Factor Corrections circuit is
present, the circuit is switched off when the set is in the
Standby mode. The Standby Line is switched low when the
set is turned on, switching the operating voltage from the
Standby Power Section to the Power Factor Correction
circuit.
The Standby Power Section begins operating as soon as
power is applied to the set and the AC Mains Switch is turned
on if one is present. This circuit produces a +5 volt and a
+3.3 volt standby voltage. The +5 volt standby voltage
supplies power to the Full Power Supply Relay while the +3.3
volt standby voltage is applied to the Microprocessor
(Painter) located on the Small Signal Board.
When the Microprocessor pulls the Standby line Low, the
Startup Run Switch is turned On, switching the Neutral side
of the AC Mains to the Full Power Supply. This provides the
Startup voltage for the Full Power Supply. Once the Full
Power Supply is operating, a 14 volt supply is generated to
provide operating voltage. The Full Power Supply provides
a 130 volt supply for the Scan circuits, a plus and minus 32
volt supplies for the Convergence circuits, a +15 volt supply
for the Scan supply, a +15VSSB supply for the Signal
circuits, and a AMP_VCC supply for the Audio Amplifier
circuits.
9.1.2
AC Input circuit with Power Factor Correction.
The AC Mains are connected to 1108, pins 1 and 4. The ac
is fused by 1000 and then fed to two line chokes, 5000 and
5001. Spark gaps 1003, 1002, 1001, 1005, and 2004 provide
lighting protection. AC is then routed through the AC Mains
Switch before being applied to the Power Factor Correction
circuit.
Figure 9-1
9.1.3
AC Input circuit without Power Factor Correction.
The AC Mains are connected to 1108, Pins 1 and 4. The ac
is fused by 1000 and then fed to three line chokes, 5000,
5001, and 5005. The AC Mains voltage is applied to bridge
6000 and filtered by 2110 to produce the Main B+ voltage.
The AC Mains are also connected to bridge 6001 to produce
RAWSTBY voltage for the Standby Section of the power
supply. This circuit is fused by 1004. Startup voltage for the
Full Power Section is taken from the Neutral side of the AC
Mains and fed to the Full Power Section on the Large Signal
Panel through resistor 3300.
CL 06532143_008.eps
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