SCD-1, SCD-777ES - Sony Audio Service Manual (repair manual). Page 8

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When the power plug has been connected, the reset signal will be output from the reset signal generator (Pin 6 of IC734) in accordance

with the power board’s DIG5V output. The reset signal will be input to the main board’s main microprocessor (Pin yd of IC701) and other
digital ICs and the display board’s display microprocessor (Pin e; of IC1001).

The reset signals for the ARP (Pin if of IC702) and the DSD decoder (Pin qd of IC703) are input via the logic ICs (IC778 and IC 726).

Using TP708, the main board’s test point, confirm that the reset signal output from the reset signal generator (IC734) is the L-pulse signal
for voltage of 5V (approx. 65µs). Confirm that the signal to the ARP (IC702) is the switch output (Pin 4 of IC778).

The system is controlled with a microprocessor (IC701).When the microprocessor starts up, the set’s operation program is read from a

4Mbyte flash ROM (IC716) and set operations are begun. The buffer for microprocessor operations has SRAM  of 1Mbyte (IC717 and
IC718). Terminal input and output information communicates with the microprocessor via a parallel data bus. Operations other than those of
the display board are controlled with serial data from the expander.

EEPROM (IC735) is provided for backing up data. The various adjustment values set when the player was shipped from the factory, the

operating mode when the power is off, etc., have been saved in EEPROM.

The display is controlled with a display microprocessor (IC1001). When the main microprocessor starts up, “SYS ERROR” will be

displayed if communication with the display microprocessor is abnormal. In this case, confirm the clock, the communication lines and the
like.

When replacing the flash ROM for program version upgrades or the like, remove the black ROM cover and replace the ROM. Remove the
ROM cover by sliding it slightly in the direction of the arrow imprinted on it. When the ROM cover has been removed, you can pull out
the ROM with your finger. After replacing the ROM, put the ROM cover back on by reversing the order in which you removed it.
Make sure never to touch the optical block during this process.

EXPANDER
     IC712

 1MB
SRAM
 IC718

 1MB
SRAM
 IC717

CPU
IC701

EXPANDER
     IC711

DISPLAY MICON
       IC1001

       4MB
FLASH ROM
      IC716

EEPROM
   IC735

D0-D7

D8-D15

EEP_SIO

SINO
SINI