12VDC Triggering (4a)
The GFA-7700 is a very high power amplifier and as such must be directly connected to the wall outlet or an appropriate surge protector or AC line conditioner. It must never be connected to the “switched” outlets on the rear panel of a pre-amplifier. Usually this would mean that when you turn on/off
your pre-amplifier you would have to turn on/off your power amplifier separately. We have however provided the ability to control the OFF/ON function of the GFA-7700 by a 12Volt DC output jack on the rear of certain ADCOM pre-amplifiers and tuner pre-amplifiers. When using this feature the front panel Power Switch must be left in the in “on” position. To connect you will need a monaural mini phone plug to monaural mini phone plug cable of appropriate length (not included) to reach from the rear panel of the amplifier to the rear panel of the pre-amplifier. Contact your dealer for information on using this feature with ADCOM and other brand pre-amplifiers. Although 12VDC is optimal, the circuit will operate from approx. 5 to 30VDC. Center conductor (tip) is positive (+).
AC Fuse (4b)
The AC Fuse protects the electronic circuits of the GFA-7700. Normally, this fuse will fail only if there is an overload within the GFA-7700. It may, however, fail if the amplifier attempts to deliver very high power into very low-impedance loudspeakers. In either case, BE SURE TO REPLACE THE AC Fuse ONLY WITH AN EXACT REPLACEMENT FUSE. The proper fuse values are:
| Fuse Rating | BUSS® | Littlefuse® |
For 115 volt operation | 15 Amp 250 Volt | AGC-5/250V | (3AG) 312005/250V |
For 230 volt operation | 8 Amp 250 Volt | AGC-3/250V | (3AG) 312003/250V |
WARNING
Before attempting to replace a failed fuse, be certain to unplug the AC Power Cord from the AC wall outlet to prevent possible electrical shock. Replace the AC 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.
If the Power LED (7) does not glow, it may be an indication that the AC fuse has blown. If you are using the 12VDC Triggering feature (above) it may be possible that there is a problem with that connection. To determine if the problem is caused by a malfunction in the 12VDC system, remove the small plug inserted into the 12VDC Triggering jack. Press the front panel power switch to turn off the amp, and immediately re-press the power switch. If the problem is caused by the 12VDC triggering circuit the amp will turn on and the LED will glow. DO NOT attempt repair of the 12VDC system. If you are not sure, or the amplifier displays other symptoms, please consult the RESOLVING PROBLEMS section on page 13. To remove the fuse-holder cap, you will need a 1⁄4” standard flat-blade screwdriver. Place the screwdriver in the recessed slot in the cap. Turn the cap 1/8-turn counter-clockwise, until the cap pops out towards you. Grasp the cap with your fingers and pull it completely out. The fuse is inserted in the back of the cap; gently pull it free.
Since the fuse has a ceramic body, you cannot visually examine the fuse element. It is therefore suggested that you replace it with an identical substitute or bring the fuse to your Adcom dealer so they may check its integrity. To replace the fuse, insert it in the back of the fuse-holder cap. Place the cap into the fuse- holder. Place the screwdriver in the recessed slot, gently press in and turn 1/8-turn clockwise.
AC Power Cord (5)
The AC cord provides power to operate all the GFA-7700’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 panel of the GFA-7700.
