A R - 1 2 2 0 A C L I N E V O L T A G E R E G U L A T O R
nal output voltage (though it may still be restored
to a usable level) but is not high or low enough to
cause an extreme voltage shutdown.
The AR 1220J has switchable output voltages, and
also has multiple scales on the Input Voltage meter
corresponding to the selected voltage.
OUTPUT VOLTAGE MONITORING
A green LED labelled OUTPUT IN REGULATION
indicates proper function (i.e., that the output voltage
is within ±5V of the selected output voltage). Your
equipment always will work normally when this light
is on, and often will work satisfactorily even when
the OUTPUT IN REGULATION LED is off.
If you wish to monitor your AR-1220’s output volt-
age more pre-cisely, you may want to use a Fur-
man Sound PL PLUS Power Conditioner and Light
Module in conjunction with it. The PL-PLUS is the
perfect complement to a Furman Voltage Regulator
to assist in rack power distribution. It offers a 20 LED
bar graph line voltage meter to monitor the incoming
line (the Voltage Regulator output), twin slide out,
swiveling lights with a dimmer control for equipment
illumination, and eight additional outlets with their own
spike and surge protection and RFI fi ltering.
DEFINITIONS
VOLTAGE REGULATION. The AC line voltage is a
number indicating the nominal electrical potential
that has been adopted in a region for powering
electrical equipment of all kinds. In most of North
America it is 117 120 volts AC; in Japan, 100 volts;
and in many other countries 220, 230, or 240 volts.
The actual voltage can fall below or rise above this
nominal level due to brownouts, power cutbacks,
use of substandard wiring, and other causes. These
deviations can cause poor performance or malfunc-
tion. A regulator is a device which, through use of a
transformer, corrects the voltage deviation by step-
ping it up or down so that it is as close as possible to
the nominal level.
SPIKE: A pulse of energy on the power line. Spikes
can have voltages as high as 6000 volts. Though
they are usually of very short duration, the energy
they contain can be considerable, enough to dam-
age sensitive solid state components in audio and
computer equipment. Spikes can also foul switch
contacts and degrade wiring insulation. They are
an unavoidable component of electric power. They
are caused unpredictably by electric motors switch-
ing on or off (on the premises or outside), utility
company maintenance operations, nearby lightning
strikes, and other factors. Spikes (also called surges
or transients) are absorbed by special components
called MOV’s in the AR series to provide safe volt-
age levels to protect your equipment.
RF11EMI INTERFERENCE: Noise from RFI (Radio
Frequency Interference) or EMI (Electro Magnetic
Interference) involves lower voltages and less ener-
gy than is found in spikes, but it is continuous rather
than transient in nature. It is not likely to cause
physical damage, but it can certainly be annoying,
producing static in audio circuits, “snow” on video
screens, or garbled data in computers. Noise can be
introduced into AC lines by nearby radio transmit-
ters, certain kinds of lighting, electric motors, and
others. Because noise occurs at higher frequencies
than the 50 or 60 Hz AC line, it can be effectively
reduced through use of low pass fi ltering.
INSTALLATION
Because of their toroidal transformer design, Fur-
man Voltage Regulators may be positioned near
most other equipment without fear that the other
equipment will be disrupted by leakage of a strong
50/60 Hz magnetic fi eld. Nevertheless, suggested
rack lo-cations would be either at the top or bottom.
As with any rack-mount equipment, be sure to use
10 32 machine screws for mounting in the rack’s
tapped holes (this is not a metric size). In particular,
beware of 10 24 screws, which may fi t if forced but
which will strip the threads. To avoid marring the
front panel fi nish, use plastic washers under the
screw heads.
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