Furman Sound, Inc. 1997 South McDowell Blvd. Petaluma, California 94954-6919 USA Phone: 707-763-1010 Fax: 707-763-1310 Web: http://www.furmansound.com E-mail: techsupport@furmansound.com Balanced AC Power Isolation Transformer, 30A MODEL IT-1230 Owner's Manual Introduction Thank you for your purchase of a Furman IT-1230 30 Amp Balanced AC Power Isolation Transformer, and congratulations on your choice. This specially wound and shielded toroidal isolation transformer is designed specifically to reduce hum pickup by sensitive equipment when ultra-low-noise is a must. Description Designed for the most critical, ultra-low-noise installations, the IT-1230 can supply 30 amps of balanced AC power to a recording studio, video or film production facility, broadcast station, etc. Its purpose is to drastically reduce hum and buzz caused both by ground currents from power supply filtering and by radiation from supply cables into sensitive signal sources like guitar pickups, tape heads and microphones. Its effect is startling! It not only dramatically reduces the noise floor but also noticeably improves dynamic range and sonic clarity. The IT-1230's heart is a specially wound and shielded toroidal isolation transformer with a center-tapped secondary. It is housed in a 3-unit (5.25" high) rack mount chassis. The back panel provides a 30-amp twistlock inlet and outlet, plus ten 20A balanced Edison outlets, widely spaced with plenty of clearance for "wall warts"; the front panel provides two more outlets. An IT-1230 can be installed in minutes, though you may require some help in choosing and wiring an appropriate supply cable. The IT-1230 provides clean and completely safe power--there is no need to "lift grounds" or compromise the integrity of safety ground wires to achieve hum reduction. Special features include an accurate, self-checking AC voltmeter that not only measures normal voltages, but also flashes eye-catching special pattern alerts for off-scale but not extreme conditions (80-90 or 130-140 volts); an Extreme Voltage Shutdown circuit to cause a protective shutdown if the unit is exposed to dangerous voltages (like accidental connection to 220V); and a special "Soft Start" circuit to prevent the large inrush surge currents and spikes that would otherwise occur at turnon and turn-off with such a large transformer. 960129-2332 Features Provides precisely balanced AC power for ultra-low-noise installations Typically gives a 16 dB improvement in background noise floor in systemwide installations Toroidal transformer with center-tapped secondary is the most efficient, compact design, with least magnetic field leakage Soft Start circuit prevents turn-on transients and high inrush currents Faraday shield reduces electrostatic coupling between primary and secondary Extreme Voltage Shutdown circuit protects against dangerously high or low input voltages Microprocessor-controlled "smart" AC voltmeter monitors line voltage, flashes alerts for marginal and extreme conditions Provides basic power conditioning functions (spike suppression, RFI filtering) Ground fault interrupter (GFCI) protection 1-9843 Background In much the same way that balanced audio lines can reduce the pickup of hum and other types of electromagnetic interference (EMI), the use of balanced AC power lines in sensitive audio, video, or computer installations can make an enormous difference in system noise. But power distribution in North America, unfortunately, is not balanced. The distribution standards currently in use were derived from practices established over a century ago, when electric power use was limited to lighting and motors--long before any EMI-sensitive applications existed. The emphasis then was on convenience (from the power utilities' standpoint) and safety, but not noise cancellation. The result was a three-wire distribution scheme in which 120V branch circuits have a hot wire and a neutral wire, with the neutral tied to a third wire connected for safety to an earth ground. The third wire does not carry any current unless there is a short circuit. This unbalanced scheme causes hum in audio circuits for two main reasons: First, the current flowing in the hot wire induces hum in any other nearby wires, which may carry vulnerable lowlevel audio signals. Second, because the impedance of chassis and cable shielding to ground is not zero, ground current flowing from power supply capacitors and from EMI pickup causes a voltage drop at 60 Hz and its harmonics which is added to the audio signals. With a center-tapped isolation transformer, the AC power feeding a studio can be balanced at its source. The current-carrying wires then are no longer "hot" (120V) and "neutral" (0V), but two equal and opposite lines of 60V each (referenced to the safety ground connected to the center tap), which add to 120V. This type of power, when run around a room, does not induce hum into nearby audio wiring, because the two power conductors induce equal and opposite voltages that cancel each other out. Similarly, ground currents are all but eliminated by the same common-mode cancellation effect. No longer is it necessary to adopt cumbersome and expensive star-ground systems or use massive bus bars or heavy ground rods. All such systems are doomed to yield only mediocre results because of the impossibility of reducing the ground impedance to zero. The common-mode rejection of a truly balanced AC supply is far simpler, cheaper, and more effective. Balanced, or "technical" power, is recognized by the US National Electrical Code (Article 530) for critical, low noise applications. INPUT 80 - 140 VAC 60 HZ 30 AMPS MAX 60 / 120V 1 Ø AC GFCI PROTECTED 30 AMPS MAX BREAKER GROUP 60 / 120V 1 Ø AC GFCI PROTECTED 20 AMPS MAX B 20 WARNING -- TECHNICAL POWER DO NOT CONNECT TO LIGHTING EQUIPMENT. FOR ELECTRONIC EQUIPMENT USE ONLY. 20 CAUTION! RISK OF ELECTRIC SHOCK. DO NOT OPEN. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL. TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN AND MOISTURE. BREAKER GROUP MADE IN U S A RISQUE DE CHOC ELECTRIQUE -- NE PAS OUVRIR AVIS: (INCLUDES FRONT PANEL OUTLETS) A 60 / 120V 1 Ø AC GFCI PROTECTED 20 AMPS MAX IT-1230 Rear View wired with 10 gauge wiring, if continuous operation near 30 amps is anticipated. A dedicated (nothing else connected) 30 amp circuit is the minimum acceptable to comply with NEC requirements. Consult a qualified electrician if in doubt. The IT-1230 is designed for mounting in a standard 19-inch rack. Because of its weight, the best position for it is at the bottom of the rack. Its toroidal transformer minimizes magnetic leakage, but nevertheless, due to its high capacity, it will radiate an appreciable magnetic field. Therefore, we recommend that it not be positioned adjacent to sensitive, low level signal processors, especially mic preamps, mixers, tape recorders, etc. Power amps may be more suitable "rack neighbors." The maximum benefit is derived from balanced power when ALL equipment in an installation is powered with it. Therefore, try to position the IT-1230 in a central location so its power can be easily distributed everywhere it's needed. If the total power consumption of all equipment exceeds 30 amps at 120 volts, delete high level or mechanical devices first (such as power amps, etc.). If possible, physically isolate any such equipment that has to be powered with conventional power through a different circuit, and route their AC cords away from all other cabling. The balanced power produced by the IT-1230 is restricted to use with electronic equipment only. Balanced power may not be used for lighting equipment, and access must be limited to use by qualified personnel only. If you are installing the IT-1230 in a rack that has rear as well as front mounting rails, you may wish to order adjustable rear rack ears from Furman. They allow the IT-1230 to be securely attached both in front and in back. Order model RRM-2. Operation Circuit Breaker/Switch: The IT-1230 has just one control: the large blue switch on the front panel that is both a precision magnetic circuit breaker and an on-off switch. This breaker will trip (snap to the "off" position) if the total current drawn through the IT-1230 exceeds 30 amps. If this occurs, reduce the load by unplugging some equipment, then flip the switch back to "on." Installation The power source to which the IT-1230 is connected must be adequate for use at 30 amps. We recommend a 30 amp circuit, LINE VOLTAGE 90 100 110 120 128 AC VOLTS Mains Below 80V 80-90 90-104 106-108 110-120 122-124 126-128 130-140 Above 140V Voltage Status Extreme (Shutdown) Low Marginal Low Medium Low Normal Medium High High High Marginal Extreme (Shutdown) Voltmeter Reading Meter off--Extreme Voltage LED flashes The LED beneath the 90V mark flashes Meter Reads in Low Red Meter Reads in Low Yellow Meter Reads in Green Meter Reads in High Yellow Meter Reads in High Red All Meter LEDs Flashing Meter off--Extreme Voltage LED Flashes Outlets OFF ON ON ON ON ON ON ON OFF Since safety agencies dictate that the 20 amp Edison outlets be overcurrent limited to 20 amps maximum, they are broken into two groups: Group A includes the two front panel outlets and two duplex receptacles on the rear. Group B is comprised of the remaining three duplex Edison outlets. Each group is protected by its own 20A breaker. The twistlock is capable of a full 30 amps, however. Soft Start/Outlets On/Off Indicator: When power is first applied to the IT-1230, the Soft Start feature is activated, indicated by a steady yellow color. Soft Start limits the inrush current to the IT-1230's transformer, which would otherwise be excessive. The result is that the IT-1230's output voltage does not reach its full level until several seconds have elapsed. When it has reached its maximum level, the LED color turns to green, indicating that all outlets are fully powered. Should the power at the IT-1230's outlets go off for any reason--either because the power switch is in the "off" position or because an Extreme Voltage Shutdown has occurred, the LED will light up red. Extreme Voltage Shutdown: This LED status indicator is normally off. It monitors a hazard particularly common in the entertainment industry: wiring faults--for example, accidental connection to 220V. The IT-1230 senses voltages that are so high or low that operation would be impossible (under 80V or over 140V) and shuts the power down before damage can occur. Upon initially applying power to the IT-1230, this indicator will be lit if the input is receiving below 80 volts or more than 140 volts, and power will not be applied to the IT-1230's outlets. If the unit has been operating with an acceptable input voltage and then that voltage goes out of the acceptable range, the IT-1230 will shut off power to the outlet and this LED will begin flashing. NOTE: If the mains power is below 80 volts and has caused the IT-1230 to remove power from its outlets, the IT-1230 will not restore power to the outlets until the mains voltage is more than 90 volts. If the mains power is above 140 volts and has caused the IT-1230 to remove power from its outlets, the IT-1230 will not restore power to the outlets until the mains voltage is less than 130 volts. The reason for this is to prevent the power oscillating on and off in marginal conditions. LED Voltmeter: This three-color, 20-LED bargraph is an accurate, self-checking AC voltmeter that continually measures the IT-1230's input voltage. The meter reads from 90 to 128 volts in two-volt steps. The normal range voltages are indicated in green, with moderate and extremely high or low voltages in yellow and red respectively (see chart on the previous page). The voltmeter provides three special flashing patterns to indicate abnormal power conditions: 1. If only the single LED located beneath the number 90 on the voltmeter flashes, voltage at the IT-1230 input is below 90 volts. Power to the IT-1230 outlets will remain on unless the incoming voltage falls below 80. 2. If all of the LEDs on the voltmeter flash, voltage at the input is between 130 and 140 volts. Power to the IT-1230's outlets will remain on unless the incoming voltage exceeds 140. 3. If none of the LEDs on the voltmeter are lit, and the Extreme Voltage LED indicator is flashing continuously, then the IT-1230 has shut down power to its switched outlets due to input voltage below 80 volts or above 140 volts. The IT-1230's voltmeter has a basic accuracy of plus or minus two volts, and extreme cold or heat may cause an additional one volt of error. Please note that the voltage reading is advisory only. The IT-1230 does not compensate for high or low line volt- age. If you frequently move your rack to different locations, derive power from generators, use long extension cords, travel internationally, or are in an area prone to brownouts, you may benefit from the use o ...