NEC DLP CINEMA NC1600C, Service Manual

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CIRCUIT DESCRIPTION
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Peripheral chip set ASSIST III (IC7200)
This IC is connected to the local bus of the CPU. The power supply is 3.3V.
The clock signals needed to drive this IC are as specified below.
• 12MHz : Fed from X7001 for internal timing circuits
• 66MHz : Fed from the CPU for internal timing circuits
• 33MHz : Fed from X7200 for PCI buses
The following functions are available:
• PI/O (8-bit x 3 ports): Interface with the MOTOR PWB
• Fan revolution control and rpm measuring circuit : ed for liquid cooling pump control in NC2500C. In
NC800C, two fans are controlled for lamp cooling.
• Key matrix driver circuit : Pulse I/O toward the key matrix circuit of the KEY PWB.
• I2C bus circuit : Interface with the I2C bus and devices in other boards.
• PCI bus circuit : Connected with various interface circuits of the PC card and Ethernet. The clock signal
of the PCI bus is maintained at 3.3MHz.
• Remote control signal decoder circuit : Used for the decoding of wired and wireless remote control
signals.
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PC card interface circuit IC7301
IC7301 is a PC card interface IC. It is connected to the PCI bus of the ASSIST III (IC7200). The CPU uses the
PCI bus of the ASSIST III and gains access to the PC card via this PC card interface IC.
The PC card socket M7300 is of the PCMCIA TYPE II and applicable to the Card Bus.
• Power supply
The power supply for IC7301 is +2.5V. This voltage is produced from S3.3V by the regulator of
IC7300.
The power supply to be fed to the PC card is obtained through changeover b5.0V and +3.3V. The
PC card inserted in the socket is detected by IC7301 to identify the applicable voltage to be supplied.
According to this identification, the required power voltage is selected by Q7307. While no PC card is
inserted, Q7307 stays in the OFF state and no power is fed to the socket.
S5.0V is fed to the +5.0V card. For the +3.3V card, the 3.3V power is produced from Standby
+5.0V by the regulator of IC7303.
• D7300 is lit up when the PC card is accessed.