SDRAM
SDCLK
SDCKE
DCS
DRAS
SWE
DQM0
DQM1
DQ0~DQ15
MA0~MA11
URST
PWR
PRD
PCE
A0~A20
AD0~AD7
MT 1389
FLASH
EEPROM
24C02
SDA
SCL
Reset Circuit
Clock
1.8V voltage
stabilization
V18
27M
Figure 3.2.2.1 Block diagram of decode circuit
2. Working principle: this decode circuit is mainly composed by MT1389, SDRAM and FLASH. The
important conditions for decode circuit working are:
1
Reset: for detail working principle, you can refer to reset circuit working principle.
2
Clock: this system adopts 27M external clock input, and clock signal needed by internal
system can be produced through internal frequency multiplier circuit.
3
Power: decode chip adopts two groups power supply which are 3.3V and 1.8V. 1.8V mainly
supplies power for internal logical control circuit here we call nuclear voltage.
When power on, reset circuit resets built-in CPU of MT1389 and FLASH; decode chip outputs reset
signal at the same time to reset other circuits. After system resets, reading signal is outputted to FLASH
to read out information stored in FLASH and machine displays power on. Servo signal starts to work in
order to check whether tray is closed to right position and whether switch is closed. If switch is not
closed, tray closing motion is performed. Until tray detecting switch is closed, machine starts to perform
disc reading function and panel display function is also performed at the same time.
Playing process: pick-up picks disc information and sends to decode circuit to decode after
processed by servo system. Signals after decoding is stored in SDRAM temporarily. When machine
needs to replay signal, decode circuit outputs information in SDRAM.
User information storage: information setted by user is stored in EEPROM, which will be stored in
IC forever if it is not upgraded or resetted by user.
Audio, video output circuit: MT1389 integrates audio video D/A convertor. Manufacture may selects
by its own need. So, part of decode audio output is nalog output and the other part is digital output. For
details, please refer to circuit principle diagram and audio circuit instruction.
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Summary of Contents for DK2810HD
Page 1: ...DK2810HD service manual DK2871HD DK2870HD...
Page 89: ...Chapter Cinque PCB board Circuit diagram Section One PCB board 5 1 1 Surface layer of Panel 85...
Page 90: ...5 1 2 Bottom layer of Panel 86...
Page 91: ...5 1 3 Surface layer of DECODE SERVO Board 87...
Page 92: ...5 1 4 Power Board 98...
