Adcom GFA-7700 - Manual (Page 7)

Front Panel
On/Off Switch (6)
The On/Off Switch controls power to the power transformer and circuits of the GFA-7700. Whenever
the GFA-7700 is energized the Power LED (7) will glow. To turn the GFA-7700 on, press the push-button.
It will remain in the “engaged” position while the unit is energized. To turn the GFA-7700 off, press the
push-button in and release and it will move to the “disengaged” position.
Power LED (7)
This LED will glow whenever the On/Off Switch (6) is turned on and the GFA-7700 is energized. The
Power LED indicates that there is AC voltage being fed to the amplifier, but it does not signify that all
the amplifier’s circuits are in operation. If, for example, one of the Thermal Protection LED (9) glows,
that amplifier channel will not produce sound even though the Power LED may still glow. When the
GFA-7700 is turned off, the Power LED will take some time to fade out completely. It may take up to 30
seconds to fully extinguish.
Additionally, the internal power transformer is provided with a thermostat which will interrupt power
into the transformer if its temperature exceeds 125°C. This high temperature will seldom, if ever, be
encountered unless the amplifier is subjected to abnormal conditions, such as operation into loads of
less than 3 ohms at very high listening levels, etc. If the AC Fuse (4) has not failed, the Power LED is
out, and the Thermal Protection LED (9) does not glow, this would indicate that the thermostat within
the transformer has opened.
Once the temperature within the transformer decreases to a normal level, the thermostat will reset
itself automatically and normal operation will resume. If you are to avoid continually tripping the
thermostat in the transformer, you must reduce the sound level demands, correct the load impedance
of the loudspeakers, or both.
7
(6) (7) (9) (8)