Transfer Characteristics; Hfdet Setting; Audio Part - Dac; I2S - Philips CDR775 Service Manual

Faultfinding Guide

Transfer Characteristics

Set the power and reset connections as described above in
"1.1.1. Supply Voltages". Connect a function generator via a
serial resistor of 1k5 to pin 4 of connector 1000. Use the
Frequencies
300 Hz
10 kHz
100 kHz
300 kHz
800 kHz
1.5 MHz
3MHz

HFDET Setting

Set the power and reset connections as described above in
"1.1.1. Supply Voltages". Connect a function generator via a
serial resistor of 1k5 to pin 4 of connector 1000. Use the
8.3.8

Audio Part - DAC

Description
The DAC used, is the UDA1320 bit stream, continuous
calibration. I2S signals from various formats can be entered at
pins 1,2 and 3. If these signals are in phase with the delivered
system clock at pin 6, the DAC will reproduce analog output
signals at pins 14 and 16. 0dB level is 0.85Vrms. These analog
signals are at 1.65Vdc level.
The DAC has features which can be checked on the input pins.
Mute will switch off the analog signals. De-emphasis is not
used, since this is done in the decoder. Attenuation of -12dB is
not used because this is also done in the decoder.

I2S

I2S is a kind of digital audio format, consisting out of 3 lines :
CLOCK, WORDSELECT and DATA.
WORD-SELECT
Word select (WS) indicates whether the data-sample is from
the left or the right audio-channel. It has the same frequency as
the sample rate of the digital audio signal. This can be 32, 44.1
or 48kHz. Normal polarity is low for a left sample and high for a
right sample. So within the low state of the WS-line the data bits
for the left channel are transferred, and within the high state the
data bits of the right channel are transferred.
CLOCK
The CLOCK signal (CLK) indicates when DataTips must be
set, and when DataTips must be read. The frequency depends
on the speed of the I2S-bus, but is always a factor of the
frequency of the WS-signal. It can be 48x, 64x, 96, 128x... .In
our case it is 48x the sample rate frequency = 2.1168MHz. The
S1 and S2 " low"
Input V
AC
< 100mV ± 20%
200mV
200mV
310 mV ± 20%
200mV
385 mV ± 20%
200mV
655 mV ± 20%
200mV
200mV
200mV
Location
No HF
F190 4.8V± 20%
F192 < 100mV
F206 4.9V± 20%
function generator as a sine wave generator with output level
of 1Vtt. Check this AC value with an AC mV-meter connected
to the input (pin 2) of the CD10 (7000) :
Pin 2 at 7000 Input V
200mV
295mV ± 20%
200mV
200mV
200mV
200mV
1.1V ± 20%
200mV
1.1V ± 20%
200mV
Figure 8-30
function generator as a sine wave generator with output level
of 500 kHz, 1Vtt. Check this AC value with an AC mV-meter :
Voltage DC
HF
4.8V± 20%
1.1V± 20%
150mV± 20%
Figure 8-31
signal is in phase with the WS-signal. Transition of the WS
always happens on a falling edge of the CLK.
DATA
DATA contains all data-bits. Data bits are set by the
transmitting device, and read by the receiving device. The
position of the DATA-bits within the WS-signal is very
important. There are several formats for this. In our case we
always use Philips I2S format, no Japanese or Sony format.
The number of data-bits per channel depends on the used
devices.
Timing of the I2S-bus, in case of Philips I2S is shown in the
next figure :
LEFT SAMPLE
WS
CLK
DATA
MSB
CDR775
S1 and S2 " high"
Pin 2 at 7000
AC
< 100mV ± 20%
330mV ± 20%
330 mV ± 20%
335 mV ± 20%
485 mV ± 20%
760 mV ± 20%
1.1V ± 20%
CL96532086_059.eps
080999
Voltage AC
175mV± 20%
-
-
CL96532086_060.eps
080999
RIGHT SAMPLE
MSB
Figure 8-32
8. GB 63
CL96532086_061.eps
080999