Alesis Fusion 6 HD Service Manual page 213

11.3. Audio
11.3.1. Internal
The schematic/PCB signal net name of failing signals will be displayed in the
list box under the heading for the appropriate PCB (Main PCB or Expansion
Digital PCB). When the net name is highlighted, the system will send a
continuous signal on that net that can be checked with an oscilloscope.
If this signal can not be found anywhere on the net, including the pin of the IC
driving the net (consult IC datasheets if necessary to determine if the pin is
an output that will drive the net), the signal net may be shorted to power,
ground, or another signal net, or the IC may be damaged or defective. If the
signal is present on the pin or on some parts of the net but not others, check
the solder joints and signal net trace continuity. If none of these are at fault,
and the signal cannot be seen, try replacing the sending IC. If the signal can
be seen everywhere along the net, try replacing the receiving IC. If the
sending or receiving IC is a BGA part (such as the FPGA U25), and no other
cause can be found, the PCB may need to be replaced.
11.4. Media
11.4.1. HD Test
WARNING!: This test is destructive to user HD data and should only be used
after User data is backed up or there are no other alternatives to diagnose
the problem. This test should also be used when the HD is replaced to verify
proper operation.
11.4.2. HD Info
WARNING!: This test is destructive to user HD data and should only be used
after User data is backed up or there are no other alternatives to diagnose
the problem. This test is for engineering purposes only and has no value to
service technicians.
11.5. Memory
11.5.1. GPIO
The schematic/PCB signal net name of failing signals will be displayed in the
list box under the heading for the appropriate PCB (Main PCB or Expansion
Digital PCB). When the net name is highlighted, the system will send a
continuous signal on that net that can be checked with an oscilloscope.
If this signal can not be found anywhere on the net, including the pin of the IC
driving the net (consult IC datasheets if necessary to determine if the pin is
an output that will drive the net), the signal net may be shorted to power,
ground, or another signal net, or the IC may be damaged or defective. If the
signal is present on the pin or on some parts of the net but not others, check
the solder joints and signal net trace continuity. If none of these are at fault,
and the signal cannot be seen, try replacing the sending IC. If the signal can
be seen everywhere along the net, try replacing the receiving IC. If the
sending or receiving IC is a BGA part (such as the FPGA U25), and no other
cause can be found, the PCB may need to be replaced.
Confidential Alesis Service Manual 8-31-0167-A