96-8005549_3-18-21
Information subject to change
25
8508 OPERATOR’S MANUAL – SECTION 8
amplifier’s internal transformers may need to be
replaced. Please see the
Factory Service
infor
-
mation at the end of this section.
8.6
Run/Standby LED Remains Amber
When the Run/Standby LED is lit solid amber, the
amplifier is in Standby mode. Press the Power
switch to the ON position to place the amplifier in
Run mode.
If the amplifier does not return to run mode, check
to see if the High/Low Line, Overtemp, or Fault
LEDs are lit, and then follow the instructions in
this section for remedying the fault condition and
returning the amplifier to Run mode.
If the remedies given fail to restart the amplifier,
the amplifier may require servicing. See the Fac-
tory Service Information at the end of this section.
8.7
Amplifier Overheats (Over Temp
Fault Condition)
There are two possible reasons why the 8500
series amplifier is overheating: Excessive power
requirements or inadequate airflow.
8.7.1 Excessive Power Requirements
An amplifier will overheat if the required power ex-
ceeds the amplifier’s capabilities. High duty cycles
and low-impedance loads are especially prone to
cause overheating. To see if excess power require-
ments are causing overheating, check the follow-
ing:
1.
The application’s power requirements fall
within the specifications of the amplifier. See
the amplifier’s
Specifications
sheet.
2.
Faulty output connections and load.
3.
Undesired DC offset at the Output and Input
signal.
If the amplifier chronically overheats with suitable
power/load conditions, then the amplifier may not
be receiving adequate airflow. To check for ad-
equate airflow, proceed with the following steps:
8.7.2
Check for Inadequate Airflow
1.
Check air filters. Over time they can become
dirty and worn out. It is a good idea to clean
the air filters periodically with a mild detergent
and water.
2.
Visually inspect fans to assure correct op-
eration while amplifier is On (I). When an
OverTemp fault occurs, the amplifier fans will
automatically be placed in continuous high-
speed operation. Any inoperative, visibly slow,
or reverse-spinning fan should be replaced.
Please see the Factory Service information at
the end of this section.
An OverTemp condition places the amplifier in
Standby mode. If the OverTemp pulse is ex-
tremely short, as in the case of defective wiring or
switches, the OverTemp pulse may be too brief to
observe.
8.7.3 Resetting After OverTemp
To reset the amplifier after an OverTemp has oc-
curred, make sure fans are running (the amplifier
fans should switch to high-speed operation when
an OverTemp fault occurs). Remove the input
signal from the amplifier and allow the fans to run
until the amplifier has cooled sufficiently and the
amplifier automatically returns to Run mode..
NOTE:
Typically, overheating that occurs in the
amplifier outputs due to inadequate airflow or very
low impedance lows will clear within 5 minutes.
Overheating in the amplifier transformers due to
excessive power requirements will take from 5 to
15 minutes to clear. Timing the cool-down period
for the amplifier may help to determine the cause
of the overheating.
If the fault condition does not clear, return the am
-
plifier for Factory Service.
8.8 Fault LED is Illuminated
The 8500 series amplifier contains protection cir-
cuitry that disables the amplifier if an output stage
is behaving abnormally. This usually indicates an
output transistor has shorted.
Summary of Contents for 8500 Series
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