Leitch DPS-475 - Initialising the Audio Sub-System; Programming the CPLD; Verifying the FPGA; The Analogue Audio Interface

If any voltage fails the test, it is probably due to incorrect component installation. If
all components are installed correctly, check the regulators (BQ1, CQ1, and CQ2) for
proper functionality.
Initialising the Audio Sub-system
This section will program the CPLD on the audio card, and will ensure that the audio
card can be controlled from the main board.
Programming the CPLD
Install the JTAG Programming Cable into header AJ1 on the audio board. Connect
the other end of the cable to the PC parallel port.
On the PC, invoke the program Xilinx JTAG Programmer.
From the File menu, select Open, and open the chain description file 843-573.cdf.
From the Operations menu, select Chain Operations and press Execute. The CPLD
device should now be programmed. If it does not, the device may be faulty or the
cable connections may not be reliable.
Once the CPLD has been programmed correctly, remove the JTAG Programming
Cable.
Verifying the FPGA
At this point, it is necessary to restart the DPS-475. On power-up, the front panel
display should indicate that the audio card is present and loaded. If there is a problem
configuring the FPGA, the front panel display will indicate this. The problem is likely
due to an inter-board communication issue. Refer to page 1of the audio schematic
743-573, reference D-2 for one possible problem area.
Once the FPGA has been loaded, the DPS-475 will enter normal operation. Verify
that the FPGA is operational by reading the version number in the system
configuration register. Compare this value with the current version number.
The Analog Audio Interface
This group of tests will ensure that the analog interface of the audio card is
functioning correctly and within specifications.
Bypass Relays
Set the audio precision analyzer impedance to 100KΩ on both channels. Mute the
outputs on the audio card. With the DPS-475 in BYPASS position, the audio precision
should measure +18dBu on both inputs. Switching the BYPASS relays off should
cause the audio precision to measure the noise floor of the audio card, at a level
somewhere below -40dBu. If the measurement is above this level, it indicates that one
or more of the bypass relays are not switching properly.
Restore the audio channels to active outputs. The audio precision should now measure
approximately +18dBu on both inputs, indicating that the audio card is processing the
analog data.
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DPS-475/575 Service Manual