Specifications

Circuit Descriptions, List of Abbreviations, and IC Data Sheets
EN 67L05.1U AA 9.
this point current flows through the opto-isolator, 7516. The
transistor inside 7516 turns On applying a control voltage to Pin
6 of 7510. If a problem should develop in the feedback circuit
causing an excessive voltage on Pin 6, Transistor 7549-2 will
turn On, switching Transistor 7532 On. This will a voltage to the
Demag circuit on Pin 7 causing the IC to latch Off. The IC will
stay latched until power is removed and reapplied to the set.
In the Standby mode, the "B" control line from the Hercules
Processor is Low. Only the +3, +3V3, and +6 volt supplies are
present. When the set is turned On, the "B" line will go High,
turning Transistors 7509, 7545, and 7535 On. This will switch
On the +8VA, +12VA, +8V, +3V3A, +6VA, and +5V supplies.
In normal operation, voltage from Pin 12 of 5504 is rectified by
6540 to produce a negative voltage which prevents Transistor
7561 from turning On. If AC is removed from the set, this
negative voltage will disappear. The voltage across the filter
capacitors on the +3V line will turn 7561 On. The Power Down
line will then go Low signaling the processor to shut the set
down.
9.2.2 Main Power Supply
The Main Power supply provides the VBAT (141 volt), and
Audio voltage supplies. This supply is switched Off during the
Standby mode. During Standby the STBY_Con line is High
which turns Transistor 7573 On. This causes the opto-isolator
7513 to turn On hard. This places a higher voltage on the
control Pin of IC 7511 causing the IC to shut down. The
operating voltage from the Auxiliary supply keeps a small
voltage on Pin 2 of 7511 to prevent it from cycling On and Off.
When the set is turned On, the STBY_Con line goes Low
switching 7573 Off. The VBAT supply is the reference voltage
for regulation. Since this voltage is missing during startup, the
Shunt Regulator 7571 is turned Off. The voltage on Pin 6 of
7511 goes Low, which turns the drive from the IC On. When the
set is On during normal operation, the supply voltage on Pin
2 of the IC is supplied by Pin 2 of Transformer 5512. When the
VBAT supply reaches the correct voltage, Pin 3 of the Shunt
Regulator 7571 reaches 2.5 volts switching it On. This switches
the opto-isolator On to provide a regulation feedback path.
Transistor 6551 provides a power on ramping of the VBAT
supply.
9.3 Video Processing
The video processing section located on the Mono Carrier
performs all of the 1fH processing. AV1, AV2, CVI, and Side
inputs are fed to this board. The CVI input on this board will only
accept 1fH signals. 1fH RGB signals from the Hercules are fed
to the ATSC module via the deflection controller board. The
ATSC module rescales the picture from the Hercules. It also
has an HDMI and CVI connection. The HDMI and CVI
connections can accept either 480i, 480p, 720p, or 1080i. The
ATSC module also has a built in Digital Tuner. The ATSC
module resizes the picture to 1080i regardless of the input.
9.4 Audio Processing
The audio decoding is done entirely via the Hercules, IC 7200.
The analogue IF output from the Tuner is fed directly to either
the Video-IF or the Sound-IF input depending on the type of
concept chosen. There are mainly two types of decoder in the
Hercules, an analog decoder that decodes only Mono,
regardless of any standards, and a digital decoder (or
DEMDEC) that can decode both Mono as well as Stereo, again
regardless of any standards.
Audio from the ATSC board is fed to the Hercules.
9.5 Deflection Controller
The Deflection panel performs the signal processing and
Deflection processing functions. YPbPr from the ATSC module
is fe to 7402 signal processor. This circuit performs the Color,
Tint, Brightness, and Contrast control functions. The Y signal is
fed to a Sync Separator to separate the Horizontal and Vertical
Sync which is output on Pins 37 and 35. RGB is output
on Pins 12, 13, and 14. These signals are sent to the CRT
panel.
Horizontal drive is output on Pin 37 where it is fed to the
deflection circuits on the Family board. Vertical Sync is output
on Pin 35 of 7402 to IC 7404. IC 7404 develops the Vertical and
EW drivefor the deflection circuits.
DC monitor signals are output on Pins 4, 6, and 7 of 7402 and
fed to an Undervoltage detection circuit. If a positive or
negative voltage develops on any of these lines, this circuit will
force Pin 21 of 7404 Low, causing the set to shut down. The
shutdown is actaviated when Pin 21 goes below 5 volts.