Yamaha PSR-S770, Service Manual

Page: 55 / 110

55
PSR-S770/PSR-S970
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PSR-S770■SYSTEM■BOOTING■FLOWCHART
If accessing SDRAM doesn’t
start, SH7731 (IC001) may be
faulty.
If accessing Program Flash
doesn’t start, SH7731
(IC001) may be faulty.
A
Power ON
Setting CPU registers.
Initializing SH7731 port.
BL-ON = L (CN401, 3)
BL-PWM =L (CN401, 4)
BL_POW_EN = L (IC412, 4)
PSWO = H (IC013, 2)
/DA-MUTE = L (IC005, 13)
/PRG-WP = L (IC008, 16)
/BACKUP-WP = L (IC010, 16)
/CPU-MUTE = L (IC009, 1)
/CPU-SP-OFF = L (IC009, 9)
/USB-IC = L (IC012, 18)
/SWP-IC = L (IC012, 17)
/DAC-IC = L (IC012, 14)
MIDI-IC = H (IC012, 13)
Initializing SH7731 port.
BL-ON = L (CN401, 3)
BL-PWM =L (CN401, 4)
BL_POW_EN = L (IC412, 4)
PSWO = H (IC013, 2)
/DA-MUTE = L (IC005, 13)
/PRG-WP = L (IC008, 16)
/BACKUP-WP = L (IC010, 16)
/CPU-MUTE = L (IC009, 1)
/CPU-SP-OFF = L (IC009, 9)
/USB-IC = L (IC012, 18)
/SWP-IC = L (IC012, 17)
/DAC-IC = L (IC012, 14)
MIDI-IC = H (IC012, 13)
Resetting negation.
/SWP-IC =H
/USB-IC = H
MIDI-IC = L
Keyboard and
switch status taken in.
BL-ON = H
BL_POW_EN = H
BL-PWM = H
/DAC-IC = H
DA-MUTE = L (IC005, 12)
Initializing EBUS driver.
(EBUS Start)
EICN = H
Initializing EBUS driver.
/SWP-IC = H
(EBUS Start)
EICN = H (IC016, 1)
/SWP-IC = L
EICN = L
BL-ON = H
BL_POW_EN = H
BL-PWM = H
Opening screen displayed.
(Tuning fork mark)
Installation screen
displayed.
No
Yes
Installation mode?
(Start SW)
Initializing SDRAM for BOOT,
0 clearing,
setting constant.
END
Installation
by user
Accessing Program
Flash (IC008) starts.
If failed to reach here, possible cause
may be in;
• SDRAM
Accessing SDRAM
(IC206, 208) starts.
Communication with
EBUS starts.
Normal
starting
ERR-DETECT pulse output
(IC006,1)
Yes
No
Test mode displayed.
Test mode?
END