Adcom GFA-585se User Manual page 17

INSTANTANEOUS DISTORTION ALERT LEDs
The INSTANTANEOUS DISTORTION ALERT circuit is a unique ADCOM distortion-detection
system which reads all forms of non-linear distortion such as THD, IM, slew-induced,
"clipping", etc. The INSTANTANEOUS DISTORTION ALERT LEDs will light when distortion
reaches 1% regardless of the impedance or the phase angle of the current voltage and the
reactance of the loudspeakers which the amplifier is driving. Sometimes, when the amplifier
is in use, the LEDs may occasionally flicker under high-volume listening, particularly if you
are driving low impedances. This flickering is no cause for concern. The LEDs are simply
warning you that the amplifier is approaching its maximum power output into the specific
loudspeakers which you are using. If, however, the INSTANTANEOUS DISTORTION ALERT
LEDs glow brightly or are on most of the time during playback, you are overdriving the
amplifier and should lower the volume control to reduce the listening-level demands, or you
may blow the AC RAIL FUSES, cause the THERMAL PROTECTION to be activated or, in
extreme cases, damage your loudspeakers.
THE LIMIT PROTECTION LED
There are two statuses for the LIMIT PROTECTION LED.
Firstly when power on the amplifier, the Limit protection LED will light 8 +/-2 seconds and
then go out, it means the amplifier is no output during these period time, you also can hear
both left & right channel output relay on and go into the operation mode.
Secondly the GFA-585se is provided with an overload protection circuit to protect amplifier
when speaker short circuit or DC voltage is happened on the amplifier output stage, the LIMIT
PROTECTION LED will light.
It means the output relay will open immediately to prevent the output transistor or other parts
from failing.
THERMAL PROTECTION LED
The GFA-585se is provided with a thermal protection circuit which will shut down the amplifier
if the temperature of either heatsinks reaches 70°C. The THERMAL PROTECTION LED will
light whenever the thermal protection circuit on either channel, or both channels, has been
triggered and the amplifier is inoperative. You will know that its heatsinks temperature has
become unacceptably high and the circuitry is protecting the amplification devices. Please
note that the POWER LED will remain on and the amplifier will still be energized.
Once the temperature of the heatsinks drops to a safe operating level, the amplifier will
automatically return to operation.
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