Circuit Description; Circuit Operations Of If-762 Board; Oscillator Circuit; Scsi Interface Circuit - Sony UP-D2550S Service Manual

4-1. CIRCUIT OPERATIONS OF IF-762 BOARD

[Outline]
Main Functions of IF-762 Board
1) Receives command data from the personal computer via the SCSI interface.
2) Sends command data to the personal computer via the SCSI interface.
3) Receives bit map image data from the personal computer via the SCSI interface and writes in
the DRAM.
4) Reads data from the DRAM during printing, and sends it to the PRT-11 board via the masking
table.
5) Determines key inputs, LED lighting
Structure of IF-762 Board
1) Oscillator circuit, reset circuit

2) SCSI interface circuit

3) DRAM and memory control

4) CPU
5) Color adjustment, masking table

4-1-1. Oscillator circuit

20MHz clocks are generated by IC202 and the ceramic oscillator X201.
All the circuits on the IF-762 board operate according to this clock. This clock is input to system
controller CPU IC204, memory controller IC102 and SCSI protocol controller IC209.
Reset circuit
IC203 is a voltage detection IC. The +5 V power supply voltage is input to pin 2 via R228, C209
and C210. A signal maintained at the low level for about 40 msec after the power is started is
output from pin 1 and used as reset signal of the system controller CPU IC204, color adjustment
IC101 and PRT-11board. After operating system controller CPU IC204, reset of memory
controller IC102, SCSI protocol controller IC209 is performed by MEMRES signal output from
pin 21.
UP-D2550S (UC,CE)
SECTION 4

CIRCUIT DESCRIPTION

4-1