Raleigh Audio RAKK dac Mark II Installation Manual - page 8
9. Refer to the Grounding section below and, if needed, install a wire between the (–) pad of
the power supply and the chassis at the point where the green-wire safety ground is
connected to the chassis.
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10. Mount the boards in their locations and secure them in place.
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Grounding
The USB is used to interconnect a variety of devices in many different ways. No single
grounding scheme is most effective in all cases; thus you may need to experiment to determine
the most effective grounding for your system. As a general guideline, devices fall into two
categories for grounding – grounded devices and ungrounded devices.
In the first category are devices like tower computers and media devices which plug into mains
power with a three-prong cord. The chassis of these devices are connected to mains safety
ground, and this ground is carried through the USB connections to other devices that are attached
to the USB interface.
When the RAKK USB to SPDIF Convertor is used in this environment, it picks up its ground
from the attaching device, such as the computer. In this case, to ensure galvanic isolation, there
must be no connection between the negative (–) terminal of the RAKK USB to SPDIF Convertor
5V power supply and the negative (–) terminal of the RAKK dac 12V power supply.
In the second category are devices like media devices which plug into mains power with a two-
prong cord and laptop computers. The chassis of these devices are not connected to mains safety
ground, and thus there is no ground to be carried through the USB connections to attaching
devices.
When the RAKK USB to SPDIF Convertor is used in this environment, since there is no ground
to be picked up from the attaching device (laptop), the RAKK USB to SPDIF Convertor must be
grounded from the RAKK dac chassis. To accomplish this, a wire should be installed between
the negative (–) terminal of the RAKK USB to SPDIF Convertor 5V power supply and the
chassis at the point where the mains green-wire safety ground is attached to the chassis.
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