Tektronix DPO3000 Series, Service Manual

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Theory of Operation
I/O Board
The I/O board contains two USB ports (one host port and one device port), an
Ethernet port (LAN), a WVGA Video port, and a Trigger Out BNC connector.
Attenuator Board
The Attenuator board contains the analog portions of the acquisition system. The
Acquisition system begins with the analog signal path, on the Attenuator board,
and ends with a digitized signal in memory, on the Main board.
The signal enters a channel input, and then passes through an attenuator and
preampli
fi er. The signal is then passed to the Main board.
Main Board
The Main board module contains the following functions:
Acquisition System The Acquisition system begins with the analog signal path, on the Attenuator
board and ends with a digitized signal in memory, on the Main board. The analog
signal from each preampli
fi er on the Attenuator board goes through a digitizer, a
time base controller, and then into acquisition memory. The analog signal from
each preampli
fi er is also distributed to a trigger circuit.
Trigger System
The Trigger system processes the analog signals from the preampli fi ers on the
Attenuator board, and sends trigger information to the time-base controller.
Advanced trigger functions are enabled only when the appropriate application
modules and supporting software are installed.
Display System The Display system combines live waveform data from acquisition memory with
menus and text, and stores this information in display memory. It then uses this
data to refresh the XGA display module (LCD).
Processor System
The Processor system contains a 440EP Power PC microprocessor that controls
the entire instrument. The processor system also contains FLASH ROM, system
RAM, and interfaces to the USB ports.
Power Converter The Power Converter receives the +12 V and +6 V from the main power supply
and generates voltages for the analog and digital circuitry on the Main board.
Digital Channels The MSO3000 series main board also includes threshold DACs and comparators
for the digital channels.
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