manual - Furman Sound

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AR-20 II Voltage Regulator / power conditionerogy. Additionally, Furman’s trusted over-voltagecircuitry protects against all too frequentaccidental connections to 208 or 240 VAC, byshutting off the incoming power until the overvoltage condition is corrected.LiFT (Linear Filtering Technology)Unfortunately, traditional AC filter - conditionershave been designed for unrealistic laboratoryconditions. Prior technologies could actuallyharm audio and video performance morethan they help, due to the resonant peakingof their antiquated, non-linear designs. Undercertain conditions, these designs can actuallyadd more than 10 dB of noise to the incomingAC line! Furman’s SMP+ with LiFT takes anotherapproach, ensuring optimal performancethrough linear filtering and no leakage toground. With this exclusive filtration technology,all connected equipment will be free ofnoise and contamination and will operate atoptimum performance levels.Extreme Voltage Shutdown IndicatorThis LED is normally off. It monitors a hazardcommon in the entertainment industry: wiringfaults – for example, accidental connectionto 220VAC where 120VAC is expected, or anopen neutral from a 208 or 240VAC feed. TheSeries II SMP+ circuit senses voltages thatare so high that operation would be impossibleand shuts the power down before damagecan occur. Upon initially applying power tothese units, the Extreme Voltage indicatorLED will light if the input voltage is above theextreme voltage cutoff, and power will not beapplied to the unit’s outlets. If the unit has beenoperating with an acceptable input voltageand subsequently that voltage exceeds 145-150V, it will shut off power to the outlet and theExtreme Voltage LED will light.NOTE: If the mains power is above the highcutoff voltage and has caused the unit toremove power from its outlets, it cannot restorepower without the operator manually turningthe unit off, then on again. Avoid turning theunit back on, without first checking the sourceof the problem, and perhaps changing the ACsource.Protection OK IndicatorAlthough the Furman SMP+ circuit assuresvirtually protection from transient voltagespikes and surges, nature has a way ofoccasionally creating electrical forces that arebeyond the capabilities of any TVSS device toabsorb without some degree of damage. Inthe rare instance that this occurs, the green“Protection OK” LED indicator located on yourfront panel will dim. If this happens some levelof protection from voltage surges will remain,but the Furman’s clamping voltage rating willbe compromised. The unit must be returnedto Furman Sound, or an authorized FurmanService center for repair.Fuses and Circuit BreakersThere is one fuse and one circuit breaker in theAR-Series. In the event that the unit appears tobe completely dead (neither the Power switchnor any LED’s light up), unplug the power cordand the load and check the breaker. If the circuitbreaker is tripped, a white button will popup. Push it back in to reset it. The purposes ofthese circuit protection devices are:1. A fast-blow 20 amp circuit breaker is accessibleat the rear panel without removing theunit from the rack. This breaker will trip if the3
AR-20 II Voltage Regulator / power conditionerunit’s 20 amp capacity is exceeded at anytime.2. A fast-blow 1/4 amp fuse is located insidethe unit. This fuse will blow if the unit hasbeen connected to a voltage that is abovethe range of the Extreme Voltage Shutdowncircuitry. To replace it, the unit mustbe completely disconnected from all powerand removed from its rack. The six hex headscrews and two Phillips head screws holdingthe top cover must be removed. The internalfuse is located in a holder on the printed circuitboard. Replace the fuse only with the exactsame type (1/4 fast blow).Input Voltage & CurrentMonitoringThe digital meter at the left of the front panelmake up a meter that indicates INPUT VOLT-AGE or CURRENT levels. A switch to the leftof the meter allows the user to switch betweenthese two readings. It is important to rememberthat this is the voltage or current coming fromthe wall before it has been regulated. This isNOT the level of voltage going into the equipmentyou have connected to the AR-20 II.Output Voltage MonitoringA green LED labelled OUTPUT IN REGULATIONindicates proper function (i.e., that the output voltageis within ±5V of the selected output voltage).Your equipment will always work normally whenthis light is on, and often will work satisfactorilyeven when it is off.The AR-20 II offers a digital voltage meter tomonitor the incoming line (the Voltage Regulatoroutput).InstallationBecause of their toroidal transformer design,Furman Voltage Regulators may be positionednear most other equipment without fearthat the other equipment will be disrupted byleakage of a strong 50/60 Hz magnetic field.Nevertheless, suggested rack locations wouldbe either at the top or bottom.As with any rackmount equipment, be sure touse 10-32 machine screws for mounting in therack’s tapped holes (this is not a metric size).In particular, beware of 10-24 screws, whichmay fit if forced but which will strip the threads.To avoid marring the front panel finish, useplastic washers under the screw heads.DesignThe AR-Series uses a design based on aneight-tap toroidal autoformer. The toroidal designassures minimal leakage of stray magneticfields, and, because of its high efficiency, a verycompact size for its rating. The Voltage Regulator’scircuitry monitors the incoming line voltagewith each cycle, comparing it to an extremelyprecise voltage reference, accurate to ±0.15%.If a voltage fluctuation requires that a differenttap be selected, the new tap is electronicallyswitched exactly at the zero-crossing, to avoiddistorting the AC waveform. If necessary, it canswitch taps as often as once each cycle. Mostcommercial voltage regulators using multipletappedtransformers switch taps at uncontrolledtimes, thereby creating voltage spikes andclicks that can leak into the audio! Hysteresis inthe switching circuits avoids “chatter” or unnecessaryswitching back and forth between adjacenttaps. Unlike those voltage regulators thatemploy ferro-resonant transformers, Furman4
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manual - Furman Sound

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