Philips DVDR985 Technical Training Manual page 51

Servo Circuit Description
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:
The SPIDRE
The MACE3
The Encoder/Decoder
The AWSOME.
Servo Power and Reset
The Servo receives: 12Vdc, 5Vdc, 3.3Vdc and
-5Vdc from the Power Supply. There are three
2.5V supplies on the Servo Board connected to
the 3.3Vdc supply. The MACE3 is reset by the
Digital Board, via the Reset_BE signal. A Reset
signal comes from the MACE 3 for the rest of the
servo. The Mace3 is the Host for the local I 2 C
Bus.
Figure 24 - Servo Block Diagram
SPIDRE
The SPIDRE (Signal Processing IC for DVD
REwritable) is a multi-purpose analog pre-
processor IC specifically intended for writing
applications.
The SPIDRE receives two Power Supplies:
-5Vdc and 5Vdc. Its has three main tasks. One is
is to interface the Servo signals that go to the
MACE3 Servo Processor. The Second is
Preprocessor for the RF signal coming from the
disc during playback. The third is to process the
RF signal coming from the Encoder during
record.
The SPIDRE is controlled by the AWSOME via a
serial bus on Pins 35, 37, and 38. The AWSOME
communicates: gain information, data type, and
operation mode, Play or record.
The Servo signals to be processed include:
Playback HF/RF, the focus servo feedback sig-
nals, the radial feedback, the track loss signal,
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