Bose FreeSpace Business E4 II Series Service Manual page 86

Amplifier alarms – input and output
status
The Input and Output Status sections display
the fault condition which caused the alarm
and the current status of the amplifier output.
A number of fault conditions can be dis-
played in the Input Status section:
DC Sense Fault: A power supply fuse, output
FET, amplifier module, or some combination
of the above has blown. The amplifier mod-
ule should be replaced.
Amplifier Module Fault: When the Amplifier
Module fault occurs by itself it can be caused
by any of the following:
• Shorted loudspeaker line – Check the
loudspeaker line for shorts.
• System power exceeds 400W – Check that
system power does not exceed 400W.
• Loudspeaker transformer saturation –
Check that proper loudspeaker EQ is being
used or use a high-pass filter for loud-
speaker EQ.
• Line voltage too high (surge) – Check Error
Log for a rail voltage that exceeds 150V, in
70V mode, or 190V, in 100V mode.
• Line voltage too low (brownout) – Check
Error Log for a rail voltage which is lower
than normal by at least 20%.
• 70/100V mode switched with unit operating
– Check that output voltage and AC input
voltage selector are correct.
• Blown power supply fuse (as opposed to
AC line fuse) – Replace the fuse and per-
form the test procedures in this manual. If
the fuse blows again, replace the amplifier
module and retest.
TROUBLESHOOTING
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AC Power Fault: Might be an AC line dropout
or severe brownout, or simply AC power
turned off without first placing the E4 Series
II in standby mode. You can check that the
power has been removed from the unit, or
that you experienced a power dropout.
Sleep Mode: The host microcontroller has
told the amplifier and power supply to turn
off. This only occurs in conjunction with
another alarm (usually AC power fault),
because it in itself is not an alarm condition.
When an AC power dropout occurs, the
amplifier immediately shuts the amplifier and
loudspeaker relay off, then the other pro-
cessing is shut down. This all happens fast
enough to prevent data loss or corruption,
and to prevent loud pops in the loudspeak-
ers. When this occurs you should check the
alarm history to determine what other faults
occurred at this time.
High-Frequency Sense Fault: This protection
mode is designed to prevent damage to the
amplifier or loudspeakers from excessive
high-frequency audio or ultrasonic energy.
The amplifier is not capable of sustained
operation at full power in the 10kHZ to
20kHz (+) range.
Generally, this fault results in a one-time 3-
second dropout. If, when the amplifier tries
to restart after 3 seconds, the excess HF is
still present, the amp (and loudspeaker
relay) will remain off for another 3 seconds
and the loop repeats. Six of these in a row
will cause the amp to shut down, and will
trigger a Retry Fault.
When this fault occurs you can check your
program material for excessive high-fre-
quency content, or for a potential ground
loop which has created an oscillation internal
to the system. You can also reduce the
output gain for this amplifier zone in an
attempt to reduce the high-frequency energy
going to the amplifier.