TECHNICAL
DESCRIPTION
©
Cyrus
Audio
Ltd
Jun
2014
7
CD
t
Service
Manual
Issue
1
Microprocessor
control
system
System
control
is
provided
by
microcontroller
IC701
on
the
main
PCB.
The
microcontroller
accepts
external
user
commands
(IR
handset,
front
panel
keys
and
MC
‐
BUS
loop)
and
translates
them
into
instructions
that
operate
the
CD
mechanism,
via
commands
sent
to
the
servo
PCB.
The
microcontroller
communicates
with
the
decoder
on
the
servo
PCB
via
the
CD_CL
and
CD_DA
lines.
Digital
Outputs
The
digital
audio
data
from
the
servo
PCB
is
fed
to
the
main
PCB
via
cable
assembly
CON701.
The
data
is
then
buffered
by
IC601
and
IC604.
The
SPDIF
data
is
fed
to
the
optical
output
(TOTX401)
and
to
the
RCA
coaxial
output
(via
digital
transformer
L402).
Power
supplies
The
internal
regulated
power
supplies
for
the
CD
t
are
derived
from
a
switching
power
supply
on
the
main
PCB.
This
has
two
separate
outputs,
+5V
and
+10V.
The
10V
supply
drives
the
display
backlight
via
a
switchable
current
source
T702/T706/T707.
The
5V
supply
drives
the
other
parts
of
the
circuit.
Front
panel
display
The
front
panel
display
is
a
backlit
LCD
module
mounted
in
a
moulding
behind
the
front
panel.
The
LCD
module
is
driven
by
signals
from
microcontroller
IC701
pins
37
and
38
(DISP_DATA
and
DISP_SCLK).
IC701
also
reads
back
an
analogue
voltage
encoded
from
keys
pressed
on
the
front
panel
(via
KEYS_IN1
pin
7),
and
remote
control
information
from
the
eye
via
line
RC5_IN
pin
32.