7
Operating Manual - MFA-8000 and MFA-6000 Power Amplifier
6.5
Thermal Indicator
This yellow LED indicates that the internal tem-
perature of the amplifier is too high in one or more places.
Intensity of the LED is proportional to temperature above
normal. Note that if the thermal LED occasionally comes
on dimly, this is not considered excessive. If, however,
the thermal LED illuminates brightly, the limiter circuit
will activate and attenuate the input signal until operating
temperature returns to an acceptable range. If the thermal
LED remains brightly illuminated, the amplifier’s operat-
ing temperature should be reduced by one or more of the
following actions:
1. Turn down the applied input signal
2. Allow better ventilation around the amplifier
3. Increase the speaker load impedance by dis-
connecting some speakers
6.6
Protect Indicator
Protect mode in ASHLY amplifiers is automati-
cally activated during extreme fault conditions, as well
as during power-up and power-down . When in protect
mode, as indicated by the red LED, the speaker output
terminals are internally disconnected and the limiter cir-
cuit is activated for maximum muting. Conditions caus-
ing the amplifier to switch into protect mode include the
following:
1. Turn-on delay
2. Instant turn off
3. Extreme internal temperature (this will only oc-
cur after other thermal management efforts within
the amplifier have failed to bring internal operat-
ing temperatures within safe levels)
4. Abnormal high frequency/high amplitude signal
5. DC voltage at the output (signals below 8 hertz
will be interpreted as DC voltage, and may trig-
ger the protect circuit)
6. Output short circuit
After the abnormal condition ceases, the ampli-
fier will automatically recover from protect mode.
Dual Monaural Amplifier
0(Clip)
-3
-6
-9
-12
-15
-18
-21
-24
-27
-30
Channel Two Output Level
Limit
Thrm
Protect
MFA-8000
