Faultfinding Guide
GB 63
CDR779
8.
8.3
CD Main Board
The CD main board is built around the compact disc
mechanism VAM1250 and a loader 1250. The CDM delivers
diode signals and an unequalised high frequency signal.
These signals are necessary inputs for the decoder CD10.
Based on these signals the decoder will control the disc. The
decoder is able to control the sledge, focus motor, radial
motor and turn table. When everything is "locked", the
decoder delivers a digital output according to IEC958
standard, subcode to the microprocessor and I2S for
reproducing analog audio signals by means of a D/A
converter.
The microprocessor controls the CD10 and is slave of the
master processor on the CDR main board in the CDR779.
Both processors communicate via a DSA connection (data,
strobe and acknowledge).
Figure 8-17
8.3.1
Supply Voltages
Description
The CD main board re5V and +12V from the CDR
main board via respectively pin 16 and pin 15 of connector
1208. The +5V is split up into +5VHF and +5V. The +5VHF
is used mainly for the diode currents and the HF-amplifier.
The +5V is used for the digital part of the board. On the board
a +3V3 is made from the +5V for the decoder CD10 and an
A3V3 for the DAC UDA1320. The +12V is split up into A12V
for the audio output stage and +12V for the power drivers of
the CDM.
Measurements
Connect following supplies to next pins :
•
+5V + 5% to pin 16 of connector 1208.
•
+12V + 5% to pin 15 of connector 1208.
•
Ground reference to pin 17 of connector 1208.
Keep microprocessor 7202 in reset by forcing pin 7 of
connector 1208 to +5V. Check the following voltages :
Figure 8-18
8.3.2
Clock Signals
Description
The microprocessor has its own Xtal or resonator of 12MHz.
The CD10 needs a clock of 8.4 100ppm. This
speed also relates to the disc speed. To avoid locking
problems between the two drives in the CDR779, both drives
run on the same clock. Therefore the CD main board gets the
clock for the decoder from the CDR main board via pin 2 of
connector 1208.
The DAC needs a system clock to drive its internal digital
filters and to clock the I2S signals from the decoder. In our
case this is 11.2896MHz (CL11) generated by the CD10.
Measurements
•
Connect the power supply as described above in "1.1.1.
Supply Voltages".
•
Connect on pin 2 of position 1208 a clock signal of
8.4672 MHz ( 100ppm minimum rise time of 50ns and at
TTL level (0V and +5V).
•
Keep microprocessor 7202 in reset by forcing pin 7 at
position 1208 to +5V.
•
Release the reset. Now, the processor will reset the
CD10 for at least 75
µ
s.
•
The output clock CL11 should be available now at pin 42
of the CD10.
Check the following frequencies :
Figure 8-19
8.3.3
CD10 Decoder/Servo SAA7324 (7000)
Description
The CD10 is a single chip combining the functions of a CD
decoder, digital servo and bitstream DAC. The decoder/
servo part is based on the CD7. The decoding part supports
a full audio specification and can operate at single speed
(n=1) and double speed (n=2).
Diode signals
Radial, focus
Motor, sledge
ANA OUT
IIS, DOBM
Trigenta
HF ampl.
CD10
SERVO
DECODER
UDA1320
DAC
PROCESSOR
DSA
CDM VAM1250
Loader assy
CL96532086_048.eps
080999
Point
Voltage
Position 1000 pins 1,3
+5V
±
5%
Position 7000 pins 5,17,21,57
+3.3V
±
5%
Position 7005 pin 14
+5V
±
5%
Position 7020 pins 25
+5V
±
5%
Position 7020 pins 26,27,28
+10
±
10%
Position 7021 pin 5
+12V
±
10
Position 7022 pin 5
+12V
±
10
Position 7025 pin 16
+5V
±
5%
Position 7202 pin 38
+5V
±
5% ( other appl. 3V3 possible)
Position 7309 pins 4,13
+3V3
±
5%
Position 7120 pin 8
+12V
±
10
CL96532086_049.eps
080999
Point
Frequency
Position 7000 pin 16
8.4672 MHz
±
100ppm
Position 7202 pins 14,15
12MHz
±
5%
Position 7309 pin 6
11.2896 MHz
±
100ppm
Position 7309 pin 1
2.1168 MHz
±
100ppm
Position 7309 pin2
44.1kHz
±
100ppm
CL96532086_050.eps
080999
