Philips DVDR985 Technical Training Manual page 46

DVD Mechanism and Servo
Board
Basic Engine
The Basic Engine consists of a DVD-Mechanism
with dual laser Optical Pickup Unit (OPU), a tray
loader, a fan unit, and a PCB containing all elec-
tronics to control the module. The OPU contains
the Focus and Radial Motors. The Mechanism
holding the OPU contains the Sled and the Tilt
Motors. The electronics of the module are
responsible for all the basic servo tasks. It reads
and writes data to and from the disc.
The PCB is multilayer, using Surface Mounted
Circuitry with a very high component density.
Detailed diagnostics and fault finding are avail-
able via ComPair.
Basic Engine Block Diagram
Some specifications:
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The Servo circuit provides the interface between
the Mechanism and The Digital Signal
Processing Board. It is mostly on one board
attached to the bottom of the mechanism. It is
made up of four main circuits:
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Record DVD+R and R/W
Lossless linking
Recording speed: 1.2 x
Playback DVD, DVD+R(W), DVD (SL/DL),
DVD-R, DVD-RW (V1.1)
Playback speed: 1.2 x
Playback CD, CD-DA, CD-R, CD-RW, CD-
ROM, VCD/SVCD
Playback speed: 3 x
It controls all other functions like tray control,
start/stop, disc rotation, tracking, jumping,
and communication to the Digital Board.