Cyrus 6 DAC, Руководство пользователя

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TECHNICAL DESCRIPTION
© Cyrus Audio Ltd Jun 2014 10 Cyrus 6 DAC, Cyrus 8 DAC service manual Issue 1
The protection circuits
Over ‐ current protection is achieved by detecting the voltage across the dual emitter resistor
R219. When a high level of current is detected T304 will turn on, switching T307 on etc. The
output signal from this detector is then sent to the microcontroller.
If the DC conditions of the amplifier drift beyond acceptable limits, this is detected by IC200
and associated circuitry and protection will be activated.
Thermal protection is achieved by the microcontroller detecting a high temperature reading
from the thermal sensor.
Power supply failure is detected by IC402 arranged as a window comparator. The window
range is set between 19V and 60V, as the amplifier will work between these voltages. If the
supply voltage is outside that range a power supply error signal is sent to the control
microprocessor.
Mains disconnection is detected by the control microprocessor to prevent switch off noise.
The control system
The system microcontroller and the display are housed on a PCB attached to the back of the
front panel assembly. The inputs to the microcontroller read when the keys are pressed, a
remote control or MC ‐ BUS command is received and also monitor the working status of the
amplifier via fault detection lines. The microcontroller is then configured to update the display
and set the volume, input and other sections within the amplifier.
The front panel control system PCB is connected to the main PCB via a single 25 way flexible
cable. A second 13 way flexible cable connects directly from the front panel PCB to the digital
PCB. Note that this flexible cable is inverted compared to the 25 way cable. When correctly
installed, the writing will be visible on the 13 way cable, and not visible on the 25 way cable.
The front panel control PCB changed during the course of manufacturing these amplifiers. The
second ‐ generation PCB includes a push function on the rotary encoder, whereas the first ‐
generation PCB does not. More information about the differences between the two versions is
shown on the next page.