Digital To Analogue Conversion; Optional Dac Stage Notes; Pin Connections For Sk203; Pin Connections For Sk301 - Arcam DiVA CD73 Service Manual

The CPU is located at component position U701 and
can be found on the front panel display board, the
CPU contains a Keyboard scan this is driven from
the resistive array powered by the VREF output at
Pin 98 the voltage drop sensed can be seen on Pin
97 (AVSS) and as 4.9 V on R701.
The CPU also receives and decodes the IR from
both the display board remote receiver and the rear
panel remote input 3.5mm jack.
Please note: The IR from the from the display panel
pickup device is not driven directly into the CPU it
takes a path onto the main board and into the IR
micro circuit the signal is mixed into the rear panel
sourced IR signal by the circuit based around Q301,
Q302, Q303 the result is a signal called RMIN this
signal is fed back to the display board and into Pin 32
of the CPU.
IR RC5 electrical signals driven into the rear panel
3.5 mm jack passed thru the Opto-isolator package at
location OP301 the signal is then clamped to 3v9 by
Zener diode D301 before reaching R-C filter network
provided by C340, C341 and R304 final drive is
supplied by U301(a) and U301(b).

Digital to Analogue conversion

The BCK, PCMD and LRCK lines from the DSP are
buffered by U406 (74HCU04) before arriving at the
D to A converter at location U401 (WM8740) these
lines are now labelled as BCLK, ADATA and
LRCKIN (left, right clock in).
The WMA740 DAC is driven from its own 5 Volt
supply, this can be seen on pin 8 as DVDD.
The de-emphasis flag arrives from the DSP on pin
number 27 (high = on)
The master audio clock arrives at pin 5 labelled at
DACLK and is supplied by the previously mentioned
circuit built around U402
The Audio outputs from the DAC can be seen via
an x10 probe on R416 and R414 Left channel and
R415 and R417 Right channel, these are differential
outputs and as such will have +/- offset respectively.
The differential Audio outputs from the DAC are
summed by U403a and U404a before driving into the
output Op-amps U403b and U404b, D.C errors are
removed by servo Op-amps U405a and U405b
providing a D.C coupled output.
(see page 2)

Optional DAC stage notes

As previously mention the main board has been
designed to provide a platform for other players
within the Diva range and as such provisions
have been made for the addition of optional D to
A stages; these can be connected to the flexi foil
sockets at locations SK203 and SK301 see Fig
3a/b for relevant pin information for these
sockets.
When fitting an optional Audio stage we need to
adjust the jumper settings on the existing main
board information on jumper settings appear
within Fig 4.
Fig 3a Pin connections for SK203.
Pin Number(s) Power supply and function
1 Digital ground
2,6,7,12,13,19,20 Analogue ground
3,4,5 +11v unregulated
9,10,11 +5v Digital supply (DAC)
14,15 +5v Analogue supply
16,17,18 -12v Analogue supply
21,22,23 +12v Analogue supply
Fig 3b Pin connections for SK301.
Pin Number(s) Function
1,2,5-9,18- Analogue ground
20,23,26,28,30,32.
17 Emphasis
21 Reset
22 Mute
25 Left/Right clock in (LRCKIN)
27 A DATA
29 B-Clock (BCLK)
Fig 4. Option jumper settings.
Location CD73
PL100 Open
PL202 Open
PL203 Short
PL204 Open
PL205 Short
PL300 1/2 Short
PL300 2/3 Open
PL400 Short
PL401 Short
PL402 Short
PL403 Open
Option
Open
Short
Open
Short
Open
1/2 Open
2/3 Short
Open
Open
Open
Short