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Contents

Section One

Features..............................................................
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5

INTRODUCTION

Matching Standard
Levels....................................

6

Controls..............................................................
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7

Warranty.............................................................
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7

Section Two

General...............................................................
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8

INSTALLATION

Memory..............................................................
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8

Connectors..........................................................
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8

Audio
Wiring........................................................

9

Recommended
Practices.......................................

10

Connecting Unbalanced Sources.......................... 10
Setting Audio
Levels............................................

11

Setting Alternate
Jumpers.....................................

12

Audio
Outputs......................................................

13

Audio Output
Connectors.....................................

14

Deriving
L+R........................................................

15

Control Connector
Wiring....................................

16

Remote Control
Connections...............................

17

Logic Output Connection to External Devices.....

18

Section Three

READY
Mode......................................................

19

OPERATION

Select Alternate
Mode..........................................

19

Summary of Contents for LX-1

Page 1: ...LX 1 Stereo Selector INSTRUCTION MANUAL 7 Beaver Brook Road Littleton MA 01460 978 486 0086 FAX 978 486 0081 Copyright 1992 1997 by Burk Technology Inc REV A ...

Page 2: ...2 ...

Page 3: ... Audio Wiring 9 Recommended Practices 10 Connecting Unbalanced Sources 10 Setting Audio Levels 11 Setting Alternate Jumpers 12 Audio Outputs 13 Audio Output Connectors 14 Deriving L R 15 Control Connector Wiring 16 Remote Control Connections 17 Logic Output Connection to External Devices 18 Section Three READY Mode 19 OPERATION Select Alternate Mode 19 ...

Page 4: ... Display 20 Section Four Audio Board 21 TECHNICAL DESCRIPTION Display Board 23 Logic Board 24 Section Five Table of Contents 27 DOCUMENTATION Schematics 28 Parts Location 36 Printed Circuit Board X Ray Views 38 Parts List 41 ...

Page 5: ...5 ...

Page 6: ...lifies and improves studio and transmitter systems by providing elegant selection and mixing of program sources Featuring quality flexibility and easy to use the LX 1 can serve a number of station needs Designed to be the final gateway for broadcast systems the LX 1 can serve as the hub of a multi studio complex or as the switching center for satellite network and studio feeds As a master control ...

Page 7: ...1 with very low distortion typically a few thousandths of a percent When a channel is switched off the LX 1 yields typically 100 dB of isolation This assures there will be no audible noise or crosstalk from fast forwarding of tape or hot inputs Off is OFF Not only is the LX 1 a very low noise device its extraordinary 100dB common mode rejection will reduce hum and noise from ground loops and stati...

Page 8: ...n three circuit boards Burk Technology warrants the LX 1 to be free of defects in materials and workmanship for a period of 24 months from the date of purchase Equipment will be repaired or replaced at the option of Burk Technology and returned freight prepaid to the customer Damage due to abuse or improper operation or installation of the equipment or caused by fire or flood or harsh environment ...

Page 9: ...rmer allows operation from UPS or inverter See the power supply schematic page 37 for 230 volt strapping The LX 1 has memory retention that should be adequate for normal station shutdowns and power outages however it is best not to power it from a switched power source The best practice is to leave the unit powered continuously If power is off too long the LX 1 will reset all functions to off and ...

Page 10: ...dy tally channel ON indication start and stop pulses and permit channel selection The two 12 pin connectors on the top row permit full remote control The audio connectors are located along the lower portion of the rear panel The six 6 pin connectors are the channel audio inputs and the two 12 pin connectors are for program output and Loop functions PIN 1Pin 1 of all connectors is located to the le...

Page 11: ...led as if the LX 1 input is a transformer Generally the shield should be connected to the LX 1 audio input ground terminal and left open at the source end Both the LX 1 and the sources should be connected to a secure ground A star or transmission ground system is recommended That is there should be only one path from each device to station ground It will be observed in practice that the 100dB plus...

Page 12: ...house level standard be established FIRST Field tests have demonstrated that the duplication of level tweaks throughout an installation can deteriorate total system performance Your station can measure better and sound better if the least amount of amplification and the least amount of attenuation is used in the program path For example a line level network news or satellite feed should not be pad...

Page 13: ...ot available or would be inconvenient to use Normal program output level or 0 is indicated by the left and right channel yellow LEDs 0 on the display indicates either 4 or 8 dBu output The point where the LED comes on is a very accurate indication of 0 level There is a very narrow flutter range as the LED comes on This plus the visibility of the distinctive yellow LED permits accurate level settin...

Page 14: ...or in or out of the program path however it can be used for many other purposes such as switching an EBS generator Its ability to be controlled remotely and the fact that the LX 1 will return to normally selected audio when LOOP is turned off add to the usefulness of the LX 1 The 600Ω Main and Sub outputs can drive 300Ω loads with only slight effect on maximum output level and no loss of level bel...

Page 15: ...outputs The LOOP function under remote control could then switch between simulcasting FM on AM or select from a separate AM source via the LOOP input Another use for the LOOP function is for selecting an alternate program source when it is desired to return to the previously selected source This is an ideal way to generate an EBS test Another possibility is relaying EBS tests under control of the ...

Page 16: ... 30dB it is suggested that it be attached to an output that is not feeding an FM transmitter Each of the six channel control connectors provides tally of READY and channel selection See figure 11 Channel Control Wiring Momentarily switching pin 3 to ground will select the channel Pin 6 is control common READY toggle is available on Remote Control connector A pin 10 Pins 1 and 11 of remote control ...

Page 17: ...l devices When a channel is switched on an open collector output on pin 5 will pulse low When a channel is switched off pin 4 will pulse low The start and stop pulses are approximately one second long Lamp control and start and stop pulses are open collector outputs that can sink 250 mA 28 volts See figure 15 for methods of interfacing these control functions to other equipment Figure 12 Control C...

Page 18: ...adds to the flexibility of the LX 1 Control is possible from either the channel control connectors or from the remote control connectors This flexibility allows the LX 1 to be controlled from external control panels or the station s remote control system or both Open collector status outputs on the remote control connectors are separate from those for the front panel and those provided on the chan...

Page 19: ...onnections to External Devices Figure 15 Logic Output Connections to External Devices Methods of interfacing the open collector outputs of the LX 1 to external lamps status indicators and machine start and stop circuits ...

Page 20: ...ul when each studio has its own selection button Accidentally pressing a button will not then switch studios In the READY mode channel selection LOOP and MIX control is possible from the front panel or from remote locations Momentary closure on any channel select pin will select that channel and illuminate the selection status indicators front panel lights and remote control status When the MIX li...

Page 21: ...ry to indicate o dB at 4 dBu output The actual output level will depend upon the setting of the output level jumpers See page 7 on how to set the jumpers The display lights green over the lowest 7 segments yellow at 0 and red for the upper 4 segments The upper five segments have a peak hold feature Left and right displays may be calibrated by means of trimmers V1 and V2 located on the LX 1 Display...

Page 22: ...transformer provides 12 volts for logic use and 22 volts for the audio circuitry The 12 volt winding is bridge rectified by D 1 D4 D 5 and D8 A 2700 uF capacitor C3 filters the rectified voltage and applies it to two 6 volt regulators U3 and U4 U3 provides 6 volts for external connector use and is current limited to 500 mA U4 provides 6 volts for the logic board Unregulated 12 volts is supplied to...

Page 23: ... 20dB Attenuating the input signal prior to summing cancels out the 6dB gain that normally occurs in summing In this way the input capability of the LX 1 is increased by 6dB over normal designs This combined with operating at 1 8 volts increases the input range of the LX 1 without compromising common mode rejection The differential amplifier outputs are coupled through decoupling caps to the SSM 2...

Page 24: ...n program amplifier In this case however pairs of 21 42s are driven for each output This parallel arrangement can produce 30dBm with very low distortion Output source impedance is 25Ω and is ideal for driving studio wiring and telco lines See schematic page 36 Display Board The display board mounted behind the front panel holds the three mode switches the six select switches and the audio bar grap...

Page 25: ...across the main power input to the logic board When power is off a power off command PWOFF is generated The purpose of PWOFF is to extend memory time by disabling current draining circuitry when power is off AND gates Ull U12 and U27 hold the inputs of the peripheral drivers to logic 0 when power is off The LX 1 will not accept control commands when power is off All switch inputs are de bounced by...

Page 26: ...5 changes state whenever a channel button is pressed Sensing this change NAND gates U24 and part of U23 generate a reset pulse of required timing U25 and U26 reset the output latches When a channel is selected the latch for that channel is held at logical 1 This turns on the analog switch on the audio board for that channel The latch also activates a dual one shot that produces start and stop puls...

Page 27: ...27 USER NOTES ...

Page 28: ...oning 33 Schematic 5 Logic Mode Functions 34 Schematic 6 Logic Latches and Drivers 35 Schematic 7 Display Board 36 Schematic 8 Power Supply 37 Layout 1 Audio Board 38 Layout 2 Logic Board 39 PC Board 1 Audio Board 40 PC Board 2 Logic Board 41 PC Board 3 Display Board 42 Parts List 1 Audio Board 43 Parts List 2 Display Board 44 Parts List 3 Logic Board 45 ...

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