Philips E-BOX, Training Manual

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SHUTDOWN
As shown in Figure 3, the Shutdown circuit turns the set Off in the event of a failure which could
damage the set. (Figure 13) If one of the Fans should fail, the Fan Fail Detect circuit will go High
turning SCR 7315 On. This will turn 7321 On, turning 7339 On, turning 7338 On, turning SCR 7333
On, which will turn 7371 On. This will turn the set Off. If a problem develops in the Audio circuit,
the DC-PROT line will go High, causing the same switching action, which will cause the set to shut
down. A thermistor on the Line Conditioner panel monitors for an excessive temperature problem.
If this circuit senses a problem, the opto-isolator 7331 will conduct, turning SCR 7332 On. This will
turn 7337 On, causing the set to shut down. If the Aa line, shown in Figure 6, goes Low, 7341 will
turn On, which will turn 7339 On, causing the set to shut down. If the PROTECTION STATUS line
goes High, the set will shut down.
The VS and VA supplies are monitored for any negative spikes by 3362, 3363, 3360, and 3361. If
any negative spikes occur, 7335 will turn Off, 7336 will turn On. The output of 7301-B will then go
High turning SCR 7302 On, causing the set to shut down. The Vrr voltage from the Plasma display
is also monitored by 7301-B. If this voltage drops, 7301-B goes High, shutting the set Off.
Connector FD176, Pin2 is connected to the Sequencer Panel (This panel may also be labeled
Discharge Panel). On the Sequencer panel, this line is labeled V-Start. If this line goes Low,
opto-isolator 7003 turns On. This causes the Fault Detect Latch line to the VS supply to go High,
shutting the supply Off.
PLASMA PANEL VIDEO SIGNAL FLOW
When the Display panel is used without the E-Box, Composite and Component inputs to the panel
are via the INPUT panel. (Figure 14) If the input is a NTSC Component input signal, the Y Cr Cb
signals are buffered by 7020, 7014, and 7025. These signals are fed to the YUV to RGB matrix.
This signal is then fed to 7013, Signal Processor. There are two Composite inputs to the panel.
The Comb Filter IC 7080 selects the desired Composite input. YC from the Comb Filter is fed to
switch IC 7095 which selects between the Comb Filter and the SVHS input. The selected YC signal
is then fed to the Signal Processor. This signal is then converted to a YUV and then to an RGB
signal inside the Signal Processor. The Signal Processor then selects RGB from the Component
input or from 7095. RGB is then output to the Audio Video Control panel. The Signal Processor
also separates Horizontal and Vertical Sync which is also fed to the Audio Video Control panel.
The E-Box provides signal and communication to the Display via the VGA in connector, AVC32.
(Figure 15) The RGB signal is also routed to the VGA-OUT connector, allowing more than one
Plasma Panels to be connected. For troubleshooting purposes, a computer monitor can also be
connected to this port.
The RGB signal is fed to 7360 which switches between the VGA-IN and RGB from the YC panel.
The RGB signal is then fed to 7300 which provides clamping, brightness, and contrast control. This
signal is then buffered and sent to the PDP Limesco panel. Black Level Feedback signals, FB-R,
FB-G, and FB-B are provided by the Gamma Amplifier on the PDP Limesco panel. This is to insure
proper dc coupling between the two panels.
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