Tektronix RTX100A, Service Manual

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Theory of Operation
RTX100A ISDB-T RF Signal Generator Service Manual
2-3
A20 PCI Backplane Board
The A20 PCI Backplane board consists of the following connectors and
circuitries:
The J100, J110, and J120 connectors are PCI slots for 5 V. The J130 connector is
a PCI slot for 3.3 V and is reserved in the future. The J100 connector is the
system slot and is used to install the CPU board (single board computer: SBC).
The J110 and J120 connectors are used to install the A12 Main board and the
A150 ISDB-T RF Output board.
The PWR_Button line (Pins 9 and 10 of J310) of the SBC is connected to the
power switch on the A35 Power Switch board through the A30 Front Panel
board. When the power switch is pressed, the SBC causes the PSON# signal to
go low. When the PSON# signal becomes low, Q10 turns on and +12 V main
power is also on. When the power switch is pressed again, its status is sent to
BIOS and the PSON# signal turns high. This circuit includes a +12 V to +5 V
DC-DC converter, a +12 V to +3.3 V converter, and a +12 V to --12 V converter.
There are four connectors in the interconnect circuit: J230, J240, J290, and J310.
J230 is used to connect the board to the LCD interface on the CPU board. J290
is used to connect the board to COM2 on the CPU board. J310 is used to connect
the board to the hard disk drive LED and reset/power button on the CPU board.
J240 is used to connect the board to the A30 Front Panel board. This circuit also
has an RS-232C level converter.
U700 (PIC Micro) controls the internal fan revolution. It gets the temperature
data from the sensors (U720 and U730) through 12C BUS and controls the
supply voltage to the fan (7 V to 11.5 V).
The IEEE1394 interface consists of the 1394b link-layer device (U110), cable
transcriver/arbiter (U120), oscillator (Y100), serial EEPROM (U140), regulators
(U130 and U230), and IEEE1394b connector (J140).
PCI and ISA Connectors
ATX Power Control Circuit
Interconnect Circuit
Fan Speed Control Circuit
IEEE1394b Interface