Cyrus CD T - TECHNICAL DESCRIPTION; Microprocessor control system; Power supplies

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).
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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.
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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.
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