A R - 1 2 1 5 A C L I N E V O LTA G E R E G U L ATO R
of the Extreme Voltage Shutdown circuitry
(approximately 200 VAC for AR-1215 and AR-
1215J; approximately 400 VAC for AR-2306). To
replace it, the unit must be completely discon-
nected from all power and removed from its rack.
The six hex head screws and one Phillips head
screw holding the top cover must be removed.
The internal fuse is located in a holder on the
printed circuit board. Replace the fuse only with
the exact same type (1/4 fast blow).
INPUT VOLTAGE MONITORING
The row of ten LED’s at the left of the front panel
make up a meter that indicates INPUT VOLTAGE.
Only one LED will light up at a time. There are two
red LED’s at the endpoints. When lit, they indicate
that the input voltage may be above or below the
point where it can be restored to the selected nominal
output voltage (though it may still be restored to a us-
able level) but is not high or low enough to cause an
extreme voltage shutdown.
The AR-1215J and AR-2306, which have switchable
output voltages, also have multiple scales on the
Input Voltage meter corresponding to the selected
voltage. On the AR-2306, there are three scales,
with the top for 220V, the middle for 230V, and the
bottom for 240V.
OUTPUT VOLTAGE MONITORING
A green LED labelled OUTPUT IN REGULATION
indicates proper function (i.e., that the output voltage is
within ±5V [±10V] of the selected output voltage). Your
equipment will always work normally when this light is
on, and often will work satisfactorily even when it is off.
If you wish to monitor your AR-1215’s output volt-
age more precisely, you may want to use a Furman
PL-PLUS Power Conditioner and Light Module
in conjunction with it [use model PL-PLUS-E with
model AR-2306].
The PL-PLUS is the perfect complement to a Furman
Voltage Regulator to assist in rack power distribution.
It offers a 20-LED bargraph line voltage meter to moni-
tor the incoming line (the Voltage Regulator output),
twin slide-out, swiveling lights with a dimmer control
for equipment illumination, and eight [ten] additional
outlets with their own spike and surge protection and
RFI / EMI 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 locations would be either at the top or bottom.
As with any rackmount 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.
DESIGN
The AR-Series uses a design based on an eight-tap
toroidal autoformer. The toroidal design assures
minimal leakage of stray magnetic fi elds, and, be-
cause of its high effi ciency, a very compact size for
its rating. The Voltage Regulator’s circuitry monitors
the incoming line voltage with each cycle, comparing
it to an extremely precise voltage reference, accurate
to ±0.15%. If a voltage fl uctuation requires that a
different tap be selected, the new tap is electronically
switched exactly at the zero-crossing, to avoid dis-
torting the AC waveform. If necessary, it can switch
taps as often as once each cycle. Most commercial
voltage regulators using multiple-tapped trans-
formers switch taps at uncontrolled times, thereby
creating voltage spikes and clicks that can leak into
the audio! Hysteresis in the switching circuits avoids
“chatter” or unnecessary switching back and forth be-
tween adjacent taps. Unlike those voltage regulators
that employ ferro-resonant transformers, Furman
Voltage Regulators are not sensitive to small errors
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