Overall Block Diagram; Information Gathering; Cd Playback - Sony CDP-CX235 Training Manual

Overall Block Diagram

At the core of the 200 disc CD Changer is the System Control (Syscon)
IC501. IC501 serves as the interface between the user and the mecha-
nism. Before IC501 can respond to the user's commands for a disc to
play, it must know the following:
· If the Disc door is closed.
· If the CD Mechanism is in the chucked position.
· At which disc slot is the tray table is positioned.
Some of this information is stored in an external memory IC; the remain-
der IC501 will have to gather at power ON using the sensors and switches
linked to the Door, Tray Table and Loading Motors.

Information Gathering

Pressing the power ON button causes IC501 to use "IC SW" to switch on
regulator IC506. IC506 apples power to the BD board, which houses the
optical assembly. D+5V is also applied to the LED in the door compart-
ment to inform the user power is ON.
After Syscon IC501 turns on power, IC501 accesses its external memory
IC. Data about the disc last loaded in the CD Mechanism is returned to
IC501. The disc label information is output as data to the FL Display IC
for display on the front panel fluorescent tube. If there was no label infor-
mation, then just the disc's number is displayed.
Syscon now takes a series of steps to check the memory information:
1. Syscon activates the disc door motor to close the door if its corre-
sponding switch indicates the door is open.
2. Next, Syscon checks the loading motor switch position to see if the
CD Mechanism is in the chucked position (disc loaded).
•
If chucked, IC501 will initiate disc PB to read its TOC.
•
If unchucked, IC501 will drive the tray table motor, rotating its discs
past the disc sensors. While the tray is rotating, the tray sensors
inform IC501 of the disc slot location while the disc sensor tells
IC501 if there is a disc present at that slot. The last disc played
according to memory will be loaded and its TOC read (if present).
3
Once Syscon IC501 is confident the tray table information is valid, IC501
turns the CD Changer control over to the user by accepting pushbutton
commands.
The user can use the front panel controls to select another disc or play
that one. When Syscon knows the loading motor is in the chucked posi-
tion (loading motor switch), the CD can be played.

CD Playback

Syscon IC501 initiates CD play by sending data, clock and latch commu-
nications to IC101 on the BD board. This causes IC101 to turn on the
laser, focus, tracking and spindle servos that employ the laser diode, along
with the focus coil, tracking coil, sled motor and spindle motor in the opti-
cal assembly.
Once these servos are operating, the disc information (RFO) is output.
RFO is received by Servo Control IC101 which:
•
Converts the data back to the original modulation scheme (EFM).
•
Error corrects the data (parity error correction).
•
Reconstructs its original pattern (CIRC).
•
Creates additional digital samples (oversampling) to reduce noise in
the final analog audio.
•
Converts the signal from digital to analog form (D/A Converter).
Analog audio is output from IC101 to the rear panel jacks.