I.R.T. ELECTRONICS PTY LTD 6 Hotham Parade, ARTARMON, N.S.W. 064 Australia Phone: (ISO Code 6) (0) 4393744 Fax: (0) 439 7439 Telex: AA30 AA-89 0x AUDIO SWITCHER 805-08-985 DESIGNED AND MANUFACTURED IN AUSTRALIA

AA-89 0x AUDIO SWITCHER INSTRUCTION BOOK Section Contents Page. General Description 3.. Technical Data 4. 3. Circuit Description 5. 4. Installation 7. 5. Circuit Diagrams 6. Parts Lists W A R N I N G OPERATION OF ELECTRONIC EQUIPMENT INVOLVES THE USE OF VOLTAGES AND CURRENTS WHICH MAY BE DANGEROUS TO HUMAN LIFE. OPERATING PERSONNEL SHOULD OBSERVE ALL SAFETY REGULATIONS. DO NOT CHANGE COMPONENTS OR MAKE ADJUSTMENTS INSIDE THE EQUIPMENT WITH POWER ON UNLESS PROPER PRECAUTIONS ARE OBSERVED. NOTE THAT UNDER CERTAIN CONDITIONS DANGEROUS POTENTIALS MAY EXIST IN SOME CIRCUITS EVEN THOUGH POWER CONTROLS ARE IN THE OFF POSITION. 805

GENERAL DESCRIPTION The AA-89 Audio Switcher is a ten input Audio Switcher designed to operate as the AUDIO FOLLOW Switcher for an IRT Video Switcher. For Stereo Audio applications two AA-89 Switchers can be controlled from one Video Switcher by connecting the Tally control lines to each of the two AA-89 Switchers. The AA-89 Audio Switcher can also be used as a STAND-ALONE Audio Switcher when it is controlled from a VA-9 Control Panel, again for Stereo applications two AA-89 Switchers can be controlled from one VA-9 Control Panel by connecting the control data lines of the VA-9 to each of the AA-89 Switchers. Provision is made on the AA-89 and the VA-9 to link pairs of the units together and so implement a 0x Audio Switcher. The input circuit of the AA-89 is designed to bridge across a balanced 600 ohm line. The output circuit will drive two 600 ohm balanced circuit loads, to a maximum level of +0 dbm. An internal 40 Volt AC powered regulated Power Supply supplies the operating voltages for the AA-89 circuitry. The AA-89 is housed in an IRT one rack unit (44mm high) 483mm (9 inch) rack mounting metal chassis. The Input and Output circuit connections are by means of compression screw terminal strips mounted on the edge of the main printed circuit board, accessible from the rear panel of the unit. Control input signals are connected via a pair of 5 pin "D" Connectors mounted on the rear panel, which are wired in parallel to allow the looping of the control signals to an extra AA-89 for Stereo applications. 805

TECHNICAL DATA Inputs: Outputs: Ten 600 ohm balanced circuit, bridging (0 Kohms) input impedance Two balanced 600 ohms Maximum Output Level: +0 dbm Frequency Response: Harmonic Distortion: Noise: Crosstalk: Control inputs: Power requirements: Dimensions: Accesories available: Switched common Audio circuit for linking to another AA-89 when a 0x Switcher is implemented +/- 0.5 db in the range 0Hz to 5KHz. (Referenced to KHz) Less than 0.% in the range 0Hz to 5KHz at an Audio level of +6dBm. With input terminated by 600 ohms:- Less than -90dBm. (Bandwidth 0Hz to 5KHz) Between inputs:- Less than 80dB at 5KHz. (Input of measured channel terminated) One of 0 grounding circuits. (Internal 4.7 Kohms pull-up resistors to + volts) OR 4 bit BCD (TTL Levels) 40V AC 7VA 44mm x 480mm x 30mm VA-9 Control Panel Instruction manual 805

CIRCUIT DESCRIPTION The Audio Input signals are switched by Relays RL to RL0 to the input circuitry of feedback amplifiers composed of (U8.Q and Q) and (U9,Q3 and Q4).the input to each amplifier is AC coupled to eliminate any DC off-set that may be present on the incoming Audio signal. Each amplifier has a gain of two to boost the signal level so that an overall gain of unity is achieved when the output signal is terminated by a 600 ohm load. The output circuitry is DC coupled through sourcing resistors R43 to R46 to set the output impedance of the amplifier. A feature of the circuitry is the isolation between each side of the balanced Audio circuit, achieved by using non-inverting amplifier circuits. This gives equal loading on each side of the balanced Audio lines, and allows the AA-89 to be used to switch a Stereo pair of Unbalanced Audio Circuits. Since unbalanced Audio circuits normally have an input impedance greater than 0 Kohms the gain in the amplifiers is then not required and could be changed to unity by removing resistors R34 and R40. Note the links LK and LK which (when completed) allow the relay common Audio circuit to be looped via TB to another AA-89 when a 0x switcher system is implemented. The Control circuit of the AA-89 is arranged so that the control signal can be either a single ground contact to one of ten inputs OR a 4 bit BCD (TTL level) signal. The one of ten grounding inputs makes the AA-89 directly compatible with the VA-4 Video Switcher TALLY circuit and thus can be used as an Audio Follow Switcher for the Video Switcher. A ground on one of the 0 control inputs is inverted by U or U3 and the resulting high logic level is passed through an OR gate U4 or U5 to switch on the appropriate relay driver transistor (Ql to Q0). Note the 0K ohm, luf RC network in the base circuit of each BC07 relay driver transistor, this interfaces the 5 volt logic to the base circuit of the transistor and also acts to give a faster TURN-OFF than TURN-ON switching action to the transistor. This means that when switching between Audio signals the original signal is released a few milliseconds before the next signal is switched through to the output. The BCD input allows the AA-89 to be used as a STAND-ALONE Audio Switcher together with a VA-9 Control Panel. A VA-9 control panel is a 0x switch panel with its own encoder and tally circuitry, it requires power from the AA-89 switcher and outputs a 4 bit BCD (TTL level) signal to control the switching of a AA-89. Provision is made on a VA-9 to deselect a companion control panel when two panels are used together with two AA-89 switchers to implement a 0x Audio Switcher. A 4 bit BCD signal applied to the inputs of Ul will be decoded to a one of 0 signal to be passed through an OR gate U4 or U5 to switch on the appropriate relay driver transistor. 805

CIRCUIT DESCRIPTION When the one of 0 grounding input circuitry is used to control the AA-89, pullup resistors RN3 apply a signal to inputs of Ul the decimal decoder overranging its circuit and no output will be selected by it. Note this feature is not available in the 408 decoder C of some manufacturers care must be taken if replacement is ever necessary. Similarly when the 4 bit BCD signal is used to control the AA- 89, pullup resistors RN give logic low signals at the outputs of U and U3 and no output will be selected from the one of 0 control input circuits. The power supply consists of two bridge rectifier circuits and three terminal integrated circuit regulators to provide +/- 5 volts to operate the audio amplifiers, + volts for the relays and + 5 volts for the logic circuits. 805

INSTALLATION The AA-89 is housed in a 483mm (9 inch) rack mounting chassis one rack unit (44mm) high. Signal Connections are by means of compression screw terminal strips, which plug into sockets mounted on the rear of the printed circuit board and protruding through the rear panel of the chassis. The Input and Output connection sets consist of groups of three terminals vis. Active+; Active-; Ground. Input to the left of the chassis looking at the rear. Control Signal Connections are made to a pair of 5 pin 'D' sockets on the rear panel. Note: The 5 pin connectors are wired in parallel to allow one to be used for control signal wiring from the control switcher or control panel and the other to loop control wiring to a second AA-89 when pairs of switchers are used as a Stereo Switcher. This eliminates the need for wiring different cable sets to the same plug. The Connections are: a) For interfacing to a VA-4A Video Swithcher Pin Input Grounding control signal " " " 3 " 3-4 " 4 " 5 " 5 "6 " 7 " " 6 7 " 8 " 8 9 " 9 " 0 " 0 7 GROUND b)for interfacing to a VA400/40 Video Switcher or VA-9 RCP " Bit A BCD Input (TTL level) 0 " B ".. 9 " C 8 D " 7 GROUND 4 +5 volt power for VA-9 Control Panel Note. when connecting two AA-89 and two VA-9 units together to make a 0x Audio Switcher complete links LK and LK on the AA-89 circuit board and wire the two switchers audio common circuits together by connections to terminal blocks TB-. Note. when looping the control signals from a VA-9 control panel to two AA-89 switchers for Stereo operation, only loop the control and ground wiring, between the AA-89 swithers. DO NOT loop the +5 volt line. The AA-89 switchers source the +5 volts to operate the VA-9 circuitry, thus only one AA-89 must have its +5 volt line connected to the VA-9 control panel. 805

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! Part No. I.R.T. ELECTRONICS FTY.LTD. Replacement Parts List 805 0x AUDIO SWITCHER AA-89 ISSUE 3 Page of 80535 PC803 PC8033 DN5SY TB5 L78 0X5. 5A 70-P3 FR840 8054 8055 8056 80333 8046B SNU/050/7/4 80335 33G R03-0/00 5.60.0353 5.60.0653 Description. PCB SUB-ASSEMBLY PCB CONNECTOR "D" PCB TRANSFORMER MOUNTING SOCKET 5 PIN D [PCB] THREADED BLOCK FUSED APPLIANCE INLET (IEC30) 0x5mm 500mA PUSHBUTTON LEVER DPDT TRANSFORMER POWER FRONT PANEL AA-89 REAR PANEL AA-89 BASE PLATE AA-89 SIDE PANEL R/U MOUNTING BRACKETS "U" NUTS 6BA CHASSIS COVER LED GRN INCL HOUSING DIP CABLE ASSEMBLY AA-89 PLUG 3 PIN 8/3 PLUG 6 PIN 8/6 Qty i o pr 9 3 5 Jl, Jl, Fl Fl SW Tl LP PI, TB.3 TB Get Ref. SUP 68 68 6 35 0 43 9 39 * 6 70 6 9 99 6 6 805 0/0/89

I.R.T. ELECTRONICS FTY.LTD. Replacement Parts List 80535 PCB SOB-ASSEMBLY AA-89 ISSUE 3 Page I of Part No. Description. IQty Get Ref.,Sup! RMF55-00R RMF55-70R RMF55-470R RMF55-K RMF55-4K7 RMF55-0K RSM55-00K RMF55-lMeg RSM5-0K 09-4K7 CC7P CC0P CC470P CC00N CC470N RB4.7/63 RB0/5 RB47/5 RB470/35 TT/35 TT./35 TT/6 N4004 N448 BC07 BC77 9050-09-0 NE5534 RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W 5% RESISTOR METAL FILM.5W % RESISTOR NETWORK 9x4K7 CAPACITOR CERAMIC 7pF CAPACITOR CERAMIC 0pF CAPACITOR CERAMIC 470pF CAPACITOR CERAMIC loonf CAPACITOR CERAMIC 470nF CAPACITOR ELECTRO 4.7uF 63V CAPACITOR ELECTRO louf 5V CAPACITOR ELECTRO 47uF 5V CAPACITOR ELECTRO 470uF 35V CAPACITOR TAG TANT luf 35V CAPACITOR TAG TANT.uF 35V CAPACITOR TAG TANT uf 6V DIODE POWER A DIODE 75V 00mA NPN GP AUDIO TRANSFORMER PNP GP AUDIO TRANSFORMER TRANSISTER STANDOFF TO-8 HIGH PERFORMANCE OP-AMP 4 8 4 0 4 8 0 4 3 8 0 4 R35,4 R43,44,45,46 R3.37 R47 RN R-30,3,36,38,4,RN,RN4 RN3 Rl-0 R33,34,39,40 RN 04, C5, C3.0 06,7,3,4,9,35-37 C8 0-0 0,,8,9 C38,39 C5,6,7 03,34 030,3 C33 Dll-8 Dl-0 Ql-,3 Q.4 Ql-4 U8,9 49: 49: 9: 43: 43: 43: 9: 9: 8: 8: 8: 8: 67: 67: 67: 8 8 43 8 80535 0/0/89

! Part No. I.R.T. ELECTRONICS PTY.LTD. Replacement Parts List 80535 PCB SOB-ASSEMBLY AA-89 ISSUE 3 Page of 78L05 78L 785 795 6073 THM 408 4049 407 W308T W34T W36T V300WA04 Z5. 598. 6353 Z5. 598. 6653 Z5. 598. 753 H07Z0 PC80096 Description. C REGULATOR 5V. A C REGULATOR V. A C REGULATOR 5V A C REGULATOR -5V A HEAT SINK TO-0 C DECIMAL DECODER C HEX INVERTER C QUAD I/P OR C SOCKET 8 PIN C SOCKET 4 PIN C SOCKET 6 PIN RELAY C/0 9-4V SOCKET 3 PIN 8/3 SOCKET 6 PIN 8/6 SOCKET PIN 8/ PCB PINS PCB AA-89.AA-90 Qty 3 3 5 0 3 0 U3 U U0 Ull U0 Ul 0,3 U4,5,6 U8.9 U4,5,6 0,,3,8, RL-0 TB.3 TB TB Get Ref. SUP! 8: 99: 99: 99: 69: 6: 6: 6: 54: 68: 80535 0/0/89