Adcom GFA-5400 - Protection Circuit Power Supply PCB Components

There are several different ways to connect the wiring to the RIGHT and LEFT OUTPUTS. The methods used will
depend on the specific type of connectors supplied with the loudspeakers, the speaker cables, etc. As a matter of course, we
prefer the use of banana plugs, generally it is the most secure method of connection. Also, the springs of the banana plugs
create a self-cleaning action, which ensures the best contact between the binding posts and the connectors themselves. There
are “sockets” provided in the center of the binding posts’ studs which permit secure seating of the banana plugs. Before
inserting the banana plug into the binding post, ensure the binding post is securely hand tightened in a clockwise direction.
Additionally, when connecting the cables to the amplifier and loudspeakers, it is important that you “tin” the wires with
good quality electronic solder in order to minimize contact resistance. Tinning prevents the buildup of surface compounds,
which can form on copper wire and increase its contact resistance.
If you prefer to use other methods of connection, unscrew the insulated head of the binding post until the hole in the
binding post stud is accessible. You can then insert the bare or tinned wire, or terminal pin, through the hole. You can also use
the many variety of spade lugs available by simply placing the tines of the spade lug onto the binding post stud. Turn the
insulated head of the binding post clockwise until the wire or connector is firmly secured. Finger pressure is sufficient and you
should not use pliers or other tools, which could damage or over tighten the binding post assembly. The binding post has been
designed in such a way that finger pressure is all that is required to cause a “pinching” action among the different metal
surfaces to ensure proper connection.
All loudspeakers having nominal impedance down to 4 ohms can be connected to, and driven by the GFA-5400. The
amplifier can drive these low impedance at more than adequate power levels with no difficulty. It should be noted here that
many loudspeaker systems which are nominally rated at 4 ohms, in actuality drop in impedance, in some areas of their
frequency range, to below 2 ohms. You should not experience difficulties even with these very low impedance loads unless
you demand excessively high volume levels from the system.
In most applications, you can drive two or more sets of loudspeakers. You should note, however, that when
loudspeakers are run in parallel, the impedance presented to the amplifier is lower than the nominal impedance of each
loudspeaker. In other words, if you parallel two 8 ohm sets of loudspeakers, the resultant impedance presented to the amplifier
will be 4 Ohms If 8 ohm and 4 ohm loudspeakers are paralleled, the resultant impedance will be approximately 2.6 ohms. In
this last situation depending upon the lowest impedance of the nominally 4 ohm speakers, and if excessive power demands
are placed on the amplifier, you may trigger the THERMAL PROTECTION on the amplifier. See its respective section for more
information. For convenient switching of multiple sets of speakers with impedance protection for the amplifier, you should
consider the use of an ADCOM speaker selector. These are available from your local ADCOM dealer.
AC LINE CORD ©
The AC cord provides power to operate all the GFA-5400’s circuits. Its plug can be connected to a standard wall outlet
provided the outlet supplies a voltage compatible with the “Power” requirements printed on the rear of the GFA-5400.
The GFA-5400's power cord is supplied with a “polarized” AC plug as required by UL/CSA standards and the National
Electrical Code. To minimize the risk of electrical shock and to ensure minimal hum from the system, do not defeat the polarity
ensuring feature of the plug (one wide blade and one narrow blade). To prevent electrical shock, do not use this polarized plug
with an extension cord or other outlet unless the blades can be fully inserted to prevent blade exposure.
AC POWER FUSE©
The AC POWER FUSE protects the electronic circuits of the GFA-5400. This fuse will normally blow only if there is an
overload within the GFA-5400. For continued protection of the electronic circuit the fuse should only be replaced with a fuse of
the same type and value as printed on the rear panel of the amplifier.
If turning on the amplifier does not cause the POWER LED to glow, this may indicate that the AC POWER FUSE is
blown. Unplug the AC LINE CORD from the AC wall outlet and turn the AC ON/OFF SWITCH off and check the fuse. If the
fuse is blown, replace it only with one of the same type and value as printed on the rear panel of the amplifier. If, after
replacing the fuse, it blows immediately upon turning on the amplifier (POWER LED does not glow), a failed electronic
component or other internal problem must be suspected. Make no further attempts at fuse replacement or operation of tne
amplifier Refer the problem to competent ADCOM authorized service personnel.
To remove a blown or suspect fuse from its holder, use only a # 2 Phillips screwdriver to prevent damage to the fuse
holder Simply press lightly on the fuse holder cap and turn counterclockwise. The cap will pop out after a quarter turn. Once
a new fuse has been installed in the fuse holder cap, insert it into the fuse holder body and press lightly while turning the cap
clockwise until it is firmly seated. Be certain not to cause cross threading of the fuse holder body and cap to prevent damage to
the fuse holder. DO NOT FORCE THE FUSE HOLDER CAP INTO THE THREADS.
WARNING!
Before attempting to check or replace a blown fuse, be certain to unplug the AC line cord from the AC wall outlet to
prevent possible electrical shock.
Replace the AC POWER FUSE 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.
AC POWER FUSE For 115 Volt operation: 8 AMP AGC/250V
AC POWER FUSE For 230 Volt operation: 4 AMP AGC/250VAC_
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