Bose FreeSpace E-4 Manuale d'uso - Pagina 8

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8.3.4 Amplifier alarms

Each ampliﬁer section monitors its own operation and perfor-

mance. If a fault condition occurs, it is reported in the Ampliﬁer

Alarm section of the Error Log. Upper ampliﬁer alarms affect

channels 1 and 2, and Lower ampliﬁer alarms affect channels 3

and 4.

The ampliﬁer section of the alarm log indicates the following:

• Alarm type – The generated alarm type is the ﬁrst item.

• Ampliﬁer status – When an alarm is generated, the ampliﬁer

reports its current operating status for diagnostic purposes.

The following items are reported in the status:

Date & Time: Date and time when alarm condition occurred.

Rail Voltage: The ampliﬁer positive and negative rail voltages.

Normally, the ampliﬁer rail voltage should be between 100V

and 190V. Voltages outside this range will cause the ampliﬁer

to shut down. In the 70V mode, a normal rail voltage is approx-

imately 125V. In the 100V mode, a normal rail voltage is

approximately 165V.

Temperature: The internal operating temperature of the ampliﬁer.

Normally, this will be between 0 and 160 degrees Fahrenheit.

Output Voltage: The actual output voltage of the ampliﬁer at

the time of the alarm.

Output Current: The actual output current of the ampliﬁer at the

time of the alarm.

Input Status: The status of the input signal to the ampliﬁer.

Possible status messages are DC sense fault, ampliﬁer module

fault, AC power fault, sleep mode, high-frequency sense fault,

and retry fault.

Output Status: The status of the ampliﬁer output at the time of

the alarm. Possible status messages are "ampliﬁer module

muted," and "speaker relay off."

Fan Speed: The fan speed at the time of the alarm.

Operating Mode: The current setting of the output voltage

select switch, 70V or 100V.

8.0 E-4 System Troubleshooting

65 of 76

Amplifier alarms – using output voltage and

current

Reviewing the output voltage and current can help to diagnose a

problem. Compare the output voltage and current for each of the

two ampliﬁer outputs to determine the nature of the problem.

High Voltage

(>20V)

High Current

Driving an impedance <12Ω

(>2A)

•

Reduce total speaker load

•

Check for partial short of speaker line

High Current

Loudspeaker trans-

(<1A)

former saturation at

low frequency

• Check for proper

Speaker EQ setting

• Set Speaker EQ to

high-pass ﬁlter

Amplifier alarms – using rail voltage

Normally, the ampliﬁer rail voltage should be between 100V and

190V. In the 70V mode a normal rail voltage is approximately

125V. In the 100V mode a normal rail voltage is approximately

165V.

By comparing the + and – rail voltages, you can determine if you

are driving an impedance which is too low (<12Ω). In this case

the difference between the two rails will probably be greater than

20%.

If one of the rails shows a voltage, and the other does not, the

ampliﬁer should be replaced.

As you review all alarm records you can compare the plus rail

voltage in each of the status sections. For example, a drop of

50% in one status could indicate a brownout condition occurred.

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.

Low Voltage

(<20V)

Short on speaker line