H.f Eye Pattern - Arcam DiVA CD73 Service Manual

The laser current can be measured a voltage drop
across R101 this should directly relate to the Laser
current as set by Sony and printed label on the side
of the optical block, this will be seen as-
KS213C
18x21
dS489
The line of text at the bottom of the label that reads
dS489 indicates that this laser optic was set to
48.9mV and will read as a measurement across
R101 as 489mV +/- 5% (the tolerance of R101 itself).
We can observe the operation of the Focus control
circuit on Pin 16 of M102 (FCS), with no disc loaded,
open and close the tray the player will now search for
a disc, at this time we should se a 170 kHz saw tooth
that saw tooth should transverse through the 0V
DIGGND as the Focus coils moves the Laser lens up
and down.
The R.F going in on pins 6 – 9 feed the internal R.F
summing amplifier, we can then see the combined
R.F output as RFDC on jumper link R222. The
signal at this point should look very similar to the
diagram in Fig 3 when the scope is set to .2uS/Div
we should see roughly 400mV pk-pk.
Fig 3. H.F eye pattern
Please note: The R.F output will obviously differ from
disc to disc use the Phillips SBC 444 playability disc if
possible.
We can see the FE error output signal on R107, this
will appear as a high frequency R.F stream of 200mV
pk-pk any excessive bounce or noise on the R.F may
indicate a damaged or worn/borderline optic. The
focus is correct when (A+D) – (B+C)= 0
The tracking error (TE) signal can be seen as a high
frequency R.F stream on R218 we should expect to
see 150-200mV pk-pk, under tracking error
conditions the R.F will rise up 300-600mV pk-pk
dependent on the severity of the error. The tracking
error is derived as E - F = 0 when correct.
The RFDC, RFAC, EF, TE, SE are now fed into
U201.
The CXD3017Q micro at location U201 performs
the majority of the Data processing and control
tasks within the CD player, the micro receives the
RFDC, RFAC for processing along with the EF,
TE, SE flags these signals are fed into the micros
A/D converter and into the Servo DSP and the
PWM modulator from this point the mechanism
control signals leave the micro and travel to the
BTL driver at location U202 as SFDR, SRDR,
TFDR, TRDR, SFDR, SFD PWM lines, the
turntable motor control line leaves the micro as
MDP and is filtered and referenced to VC to form
a single SPDR line.
The presence of the +3.6V(D) power supply is
crucial to the operation of the micro's internal
PLL.
The micro initiates a programmed Disc load
procedure when the Disc tray is operated i.e. the
tray is closed. Do not look directly into the
beam.
Tray Close
o
Spin turntable motor
o
Light laser
o
Attempt focal alignment
o
Read TOC
o
o If the player fails to read the disc check.
Movement of Laser lenses.
o
+5V (D) supply.
o
+3.6V (D) supply.
o
+8V supply.
o
Operation of the tray micro switches.
o
Laser current.
o
Focus control.
o
The micro contains a CPU interface; this port
sends and receives Data packages from the front
panel CPU at location U701.
The active communication ports can be seen as
inputs from the CPU on DATA, XLAT, CLOK,
SYSM and XRST the output ports are SQSO (CD
text), SENS and SCOR. We should see active
data streams on SENS, DATA and SQCK and all
times when a disc is playing.