Specifications

Circuit Descriptions, List of Abbreviations, and IC Data Sheets
EN 66 L05.1U AA9.
9. Circuit Descriptions, List of Abbreviations, and IC Data Sheets
Index of this chapter:
9.1 Introduction
9.2 Power Supply
9.3 Video Processing
9.4 Audio Processing
9.5 Deflection Controller
9.6 Abbreviation List
9.7 IC Data Sheets
Notes:
•Only new circuits compared to the L05U chassis are
described in this chapter. For the other circuit descriptions,
see the manual of the L05U chassis.
• Because the service offering for the ATSC part is “Repair
by supplier” this part is not described in this chapter.
• Figures can deviate slightly from the actual situation, due
to different set executions.
• For a good understanding of the following circuit
descriptions, please use the diagrams in sections “Block
Diagrams, ...”, and/or “Electrical Diagrams”. Where
necessary, you will find a separate drawing for clarification.
9.1 Introduction
The L05 ATSC chassis is designed for the model year 2005.
This set has a fully integrated ATSC as well as a NTSC tuning
system. This set will come in a 26 and 30 inch screen sizes
in a 16x9 format. There will be a 32 inch version using a 4x3
ratio screen.
The set consists of a Main panel, CRT board, Side I/O panel,
ATSC module, and Deflection controller panel. The panels
consists primarily of conventional components with some
surface mounted devices.
The The functions for the 1fH video processing is performed in
one IC (TDA1200xx, IC7200), the Hercules chip. This IC is
located on the solder side of the Main panel. NTSC tuning and
switching for AV1, AV2, and CVI inputs are performed on the
Main panel. The CVI input located on the Main panel are for 1fH
(480i) signals only.
The ATSC Tuner and 1fH to 2Fh conversion is performed on
the ATSC module. Component inputs for the CVI HD and HDMI
are located on the ATSC module. This input can accept 480i,
480p, 1080i, or 720p signals. The ATSC module converts
whatever signal is applied to a 1080i format. The ATSC tuning
system can tune all channels in the VHF, UHF, and Cable
bands.
The Microprocessor communicates with the memory IC located
on the Main panel, Keyboard, Remote Receiver, NTSC Tuner,
Deflection Controller panel, and ATSC module. The Memory
IC retains the settings for favorite stations, customer-preferred
setting, and circuit settings. The circuit settings can be
accessed by the service technician via the Service Alignment
Mode.
On-screen graphics and Closed Caption decoding are
performed in IC 7200 for NTSC. IC7200 is located on the Main
signal panel. On-screen graphics and Closed Caption for the
ATSC channels are performed in the ATSC module..
9.2 Power Supply
Figure 9-1 Power supply block diagram
The supply is divided into two sections, the Auxiliary and Main
section, both located on the family board. A single filter and
rectifier circuit supplies both sections. The Auxiliary supply
operates in a low power mode when the load is reduced. In the
standby mode, the 3.3 and 6 volt supplies are operating. The
3.3 volt supply provides power to the processor section of the
Hercules. The 6 volt supply provides power to the IR receiver.
The Main supply is switched Off via the Standby line.
When the set is turned On, the "B" line from the Hercules
processor goes High switching 7547 which turns 7535, 7509,
and 7545 On. The +3V3A, +6VA, +12VA, and +8VA supplies
are then switched On. The load placed on the Aux Power
supply will cause it to switch to the full power mode. At the
same time, the STBY line switches Low turning the Main SMPS
supply On. The supply produces a +6 volt, +140 volt, -16 volt,
and +16 volt supplies.
The +Vaudio (+16 volt) supply switches on the degauss relay.
9.2.1 Auxiliary Power Supply
IC 7510 is the heart of the Auxiliary Power supply. In the
Standby mode, via the current sensing and Control circuits, a
low power condition is detected by the IC. The IC then goes into
a Burst Mode operation to reduce the power used by the circuit.
In the Burst Mode, the supply will operate at approximately 25
kHz. In full power operation the frequency will be approximately
66 kHz.
When power is first applied to the set, Start up is supplied to the
IC by the internal Start-Up current through Pin 14. Startup
voltage is also applied to the IC to Pin 2 by the AC_IN line
which is tied to the neutral side of the AC line. During normal
operation, power is supplied to the IC by the HOT windings,
Pins 1 and 2, of transformer 5504. Output drive from Pin 11 is
applied to the Gate of Transistor 7525. Voltage developed
across the current sensing resistors in the Source of 7525
provides current sense information to the IC. When 7525 is
switched Off, the voltage on Pin 1 of 5504 goes High. This
winding supplies the operating voltage the power supply circuit.
It also turns Transistor 7567 On causing the Gate of 7525 to
stay Low as long as Pin 1 of 5504 is High. This prevents 7525
from turning On until the field of 5504 has collapsed.
Regulation is accomplished by monitoring the +3 volt supply.
This voltage is fed to Shunt regulator 7542 which controls the
current through opto-isolator 7516. Shunt Regulator 7542
begins conducting when Pin 3 of the IC reaches 2.5 volts. At
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