Adcom GFA-5400 - Manual (Page 6)

ON/OFF SWITCH ©
The AC ON/OFF SWITCH controls power to the power transformer circuits of the GFA-5400, Whenever the GFA-
5400 is energized the POWER LED will glow. Depress the push button switch to energize the GFA-5400. Press the switch
again to turn the amplifier off.
POWER LED ©
This LED will glow whenever the AC ON/OFF switch is turned on and the GFA-5400 is energized. The POWER LED
indicates that there is AC voltage being fed to the amplifier, but it does not signify that the entire amplifier’s circuits are in
operation. If, for example, the THERMAL PROTECTION LED glows, the amplifier will not produce sound even though the
POWER LED may still glow.
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
POWER FUSE is not blown, the POWER LED is out, and the THERMAL PROTECTION LED is lit, 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.
- - - - - - - - - - ________________ - - _________ _______________________ _ ■ - — ...............................
• — .......... — • —
^ ^ ^
/ ^ \ cU stortonalert > •
\ v J Ihenvalprotection > ® •
5400
• - ' — ■ ' ' ■■■' ■' —
......... ...............— ------------------- ----------------- ••••;"----------------
e o o o
5400 Front Panel Diagram
INSTANTANEOUS DISTORTION ALERT LEDs O
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 impedance, voltage/current phase angle or the reactance of the
loudspeakers which the amplifier is driving. Sometimes, when the amplifier is in use, the LEDs may occasionally flicker during
high volume listening, particularly if you are driving low impedance loads. This flickering is no cause for concern. The LEDs
are simply warning you that the amplifier is approaching its maximum power output into the particular loudspeakers you are
using. If, however, the INSTANTANEOUS DISTORTION ALERT LEDs glow brightly or are illuminated most of the time during
playback, you are overdriving the amplifier and should turn down your volume control to reduce the listening level. If not,
excessive level may cause the THERMAL PROTECTION to be activated or, in extreme cases, damage your loudspeakers.