Adcom GFA-5500 - Manual (Page 9)

THERMAL PROTECTION LEDs ®
The GFA-5500 is provided with a thermal protection circuit which will shut down the amplifier if either heatsink’s
temperature reaches 85°C. The THERMAL PROTECTION LEDs will light whenever the thermal protection circuit on its
respective channel has been triggered and the amplifier is inoperative. The thermal protection circuitry will typically be
triggered by very high power demands into impedances much lower than the amplifier is capable of driving at those
levels. If either amplifier channel’s output through the loudspeaker(s) ceases abruptly, and one or both the THERMAL
PROTECTION LEDs glow, you will know that its heatsink 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 heatsink(s) drops to a safe operating level, the amplifier will automatically
resume operation.
NOTE
ACTIVATION OF THE THERMAL PROTECTION CIRCUITRY IN THE GFA-5500 IS AN INDICATION THAT THE
AMPLIFIER HAS BEEN OVERDRIVEN OR THAT THE LOAD THE LOUDSPEAKERS ARE PRESENTING TO THE
AMPLIFIER IS UNREASONABLY LOW. IF YOU WISH TO PREVENT RECURRING ACTIVATION OF THE
THERMAL PROTECTION CIRCUITRY, YOU MUST REDUCE THE VOLUME LEVEL DEMANDS OR CORRECT
THE LOAD-IMPEDANCE CONDITION WHICH MAY BE CAUSING ACTIVATION OF THIS CIRCUITRY, OR BOTH
EXTERNAL PROTECTION FUSES ©
There is an additional protection provided to the GFA-5500 in the form of EXTERNAL PROTECTION FUSES for the DC
rails on each channel. These fuses will blow if excessive current demands are made of the amplifier, either long term or
short term, and are meant to protect not only the loudspeakers, but the power output devices as well.
If the amplifier ceases to operate from either one or both channels, particularly during high level passages or long term
high volume playback, and the POWER LED glows while the THERMAL PROTECTION LEDs are out, chances, are that
one or more of the EXTERNAL PROTECTION FUSES are blown.
Your GFA-5500 is designed to activate its protection devices reliably, particularly when the amplifier is carelessly
operated beyond its limitations Other types of protection circuits, beyond the methods used in your amplifier usually
result in deterioration of the audio quality of the unit.
Should the EXTERNAL PROTECTION FUSES on the DC rails need to be replaced, only a fuse of identical value and
type as printed on the rear panel must be used.
WARNING
The fuses listed here and their time/current blowing points have been carefully selected and thoroughly tested to
deliver optimal performance while still accomplishing their protective functions. Replace the EXTERNAL
PROTECTION FUSES only with one identical in type and rating as printed on the rear panel. DO NOT USE ANY
SUBSTITUTE FUSES WITH DIFFERENT RATINGS OR VALUES Failure to observe this precaution may cause
serious damage to the amplifier circuits, MAY CREATE A FIRE HAZARD, AND MAY VOID THE WARRANTY.
EXTERNAL PROTECTION FUSE VALUE/TYPE; 8 AMP AGC/250 VOLT
WARNING
THERE ARE POTENTIALLY LETHAL VOLTAGES WITHIN THE GFA-5500 AMPLIFIER. REMOVING THE TOP
COVER GREATLY INCREASES YOUR CHANCE OF INADVERTENTLY EXPOSING YOURSELF TO EXTREME
DANGER. REFER ALL SERVICING TO QUALIFIED, ADCOM AUTHORIZED SERVICE PERSONNEL DO NOT
ATTEMPT TO SERVICE, REPLACE, OR REPAIR ANY INTERNAL COMPONENT YOURSELF.