SB-412A lilliClearmComn - Clear-Com
Contents
1.2. ER SUPPLY SCHEMATIC 70 DE wade w ust a rwv we 58 412 BLOCK DIAGRAM 4 pO saaaj 4 if Ther wi RO MARS A Singing yp waor esen 4 E wi 14 1 Vini 21135 1 2 co lt 4 e u 27 amp LRS Uns 8 o M per LEAI 12507 IH 5579 831509 A 2 5 gt Z wins K S n Dr S vir Je n wA 1 rdv ai dev ov A Awan m aang 09 Thar ai am 1354 l H lt m A MEUM i Auc S MEET OF SILAS awi mi Yw C AQO 517974 TINNA dev IGHD KAINIS a
3. Vive as eet AWE AS OU THY OD 1215 D83184 ang EP AS DENIS ee eS et J ew 1472812 JHII Q Ve HINAS OM ONIM NG AIDW3ASSY LV W DIINWSHIS 44050912 5 ALZ 726 Br RD Dis CGN31513 92 PING 119 57 Nuno 07 NOLLVIST 8 2 HAD IAL g OST H 5NISOQH L 3709 82 cha 37 7722 3238005 1 5 29 r 4 22 ES 3 yr Tz 067 3 ASST RG x 21018 LE av Law QLh T Lh Lh L h Butt JEP TRO Fons oaa f ow so lo e ew Prev 270222 seul I 4 Qysaw gt 1001 150 AT 128027 oot 722 L2 3077 222 22072 28 tau ihe 76 744545 AWNDIS 9 794916 9 I WSLS NABLA WWL l ROS 9 AOS TAN
4. _ _ E EN 2900419404 5 OOO HOOOOO OOOOOO O60000 56060000 1 LI 106 2 NOLVIS 103135 02831 Y TINNYHO BNNYH 03123135 NOUO 7534 03123135 3000 NO 9QA9Z Z1 490 90AZ 0 52 MS DOWNY 40 SOYNIPRL Su APL 1 ixv34S iY FOVIWA 29 0 5 30 S WNIMH3L 1Y 39Y1104 Pe AL AST dO lv 39YLY04 20 L 03112345 54 SSTWN S310N cd peers amn 1 NOVELS MIN 0 y gt amn 193135 t9 WO2831N 77 091012 ASSY wu 5508 43940 5508 SSNB 10502 NOLLYLS NOU Y1S W 15 p 51101781658 NOLYIS P NOLVIS Lj i j j j w x 5 4 TN WNNVHD NOLLYLS MI wed ua
5. behind reor panel for XLR connectors 3 23 08 for top cover screws 11 Headsets 5 Mics All headset connectors Clear Com gear are the 4 male XLR type To assure proper level and performance your head set or handset or mic should have the following characteristics Microphone type dynamic Impedance 150 250 ohms Output Level 55dBv Ear Element type dynamic Output Impedance 300 2000 ohms Clear Com offers three standard head sets all with boom mounted cancelling microphones Model CC 240B is a double muff headset and Model CC 75B is single muff both have boom activated dynamic mics with built in ON OFF switches Model DT 109 6 is a double muff headset wired for binaural 11 1 Check Out Connect a headset to the SB 412A and be sure that you can access talk and 115 ten all channels needed and that vi sual signalling works both to and from the station The brightly lit button should become go out again imme diately after the calling station s Call switch is released the light stays bright there is problem with the termination in that channel As a check for proper termination connect a belt pack to each channel and verify that the voice null occurs at approximately the 4 o clock position on the trimpot If the null occurs near or before the o clock position there is probably more than one termination
6. SB 412A Switchboard Main Station INSTRUCTION and SERVICE MANUAL if Clear Com Intercom Systems 945 Camelia St Berkeley California 94710 510 527 6666 Clear Com 810023 10 85 REV DOCUMENTATION ADDENDUM x SB 412A MANUAL kx REV A November 17 1987 xx SSCS CSS LINE GAIN LEVEL INCREASE In effecting a 44B Mic to Line increase in gain level the following changes have been made Change At 22K OHM R126 109 100 91 4 7K OHM R45 58 412 Installation 5 Operation Manual 1 INTRODUCTION A Clear Com Concept 8 58 412 Description INSTALLATION Maximum Number of Stations 3 Interconnect Cable System Architecture System Wiring Mounting the Station Station Connection Z gt e gt OPERATION A Quick Guide B Operating Controls C Special Features ISO Split Feed TECHNICAL INFORMATION Circuit Operation Maintenance amp Warranty Troubleshooting Specifications Parts Lists Component Locations BLOCK DIAGRAM 6 SCHEMATICS 35 NOTICE hile Clear Com makes every attempt to maintain the accuracy of the nformation contained in its product manuals the information is subject to change without notice INTRODUCTION 1 Clear
7. 047 ONE 10 SOV SMH 150005 CAD 100FF DISC 10 150007 CAL 200FF DISC 10 15000 CAT 1UF TANTALUM 259 A L 150019 CAE 22UF ELECTROLYTIC 169 R L 150011 CAE 100UF ELECTROLYTIC 350 R L 150013 15 DISC 10 150015 470FF CERAMIC DISC 10 509 150016 CAD OOSUF NISC 10 150021 CAE 220UF ELECTROLYTIC 35U R L 150026 39FF DISC SZ 350032 CAT 22UF 16UDC TANTALUM R L 159035 CAN 22UF MOHOLYTHIC 50V 150035 1 HONOLYTHIC 10420 509 150043 CAN 47UF HONOLYTHIC 509 150044 4 7 UF TANTALUM 359 R L 150061 680PF DISC 10 509 150065 CAE 2 2UF ELECTROLYTIC 500 150067 CAM O1UF MYLAR SOV 10 150048 0047UF MYLAR SOU 10 150678 047 MONOLYTHIC 10 509 doe we L o D OS 02 10 5 150080 CAM 22UF 10470 1009 120082 022 UF HONO CROS 10 Sov 150091 CAT 47UF 60 TANTALUM R L 150094 amp 8OFF SX DISC OR MONO SOV 2515 159098 DIFF 10 509 2 LS 15 170087 FCR FEVISED 4 CHANNEL SERIES 210075 16 FIN VIF SOCNET 210101 SOC 8 FIN SOCKET Ics 8 1 9 15 IC X 152 RISO 1435 x X X X X X X X 03 154 132 HEALER MULTI 18 FIN 214129 4241 x gt x o 21010 SOC SINGLE FIN SOCKET FOR DLC OFTION JUNFS J3 6 49345 x x x x x x X t x x x A 410001 2 9 OHHS R19 F
8. Two channel speaker station portable K8 111AP KB 112P Two channel wall plate WP 2 WP 6 Three way line splitter QP 100 Universal interface AC 10K or H In line isolator 1 Single muff headset CC 358 CC 758 Double muff headset CC 55 CC 240B Handheld mic push to talk PT 4 Handset push to talk 5 6 STAGE 9 MOUNT HEADSET STATION DIMMER OPERATOR WALL STAGE HANO MOUNT HEADSET STATION LIGHTING DESIGNER ERE L PACK FC 2 CH LIGHTIN Q DIRECTOR Push to Talk Program Feed trom Audio Console To Four Channel Rack Mount Speaker Station in Audio Booth DRESSING ROOM 1 DRESSING ROOM 2 WALL MOUNT SPEAKER STATION ORESSING ROOM 3 FOLLOW SPOTS THEATRICAL INTERCOM SYSTEM WARE HOUSE WALL CY apeaxer STATION Push to talk WARE HOUSE WALL MOUNT SPEAKER STATION SIDE ENTRANCE we GUARD MAIN RECEPTION AREA 10 5 412 11 12 SECURITY OFFICE POUR CHANNEL OFFICE 1 WALL MOUNT SPEAKER STATION OFFICE 2 EXECUTIVE LOUNGE x Push to Talk PARKING LOT ENTRY WALL PLATES ARE INSTALLED IN VARIOUS LOCATIONS THROUGHOUT CORRIDORS OF BUILDING ROAMING SECURITY GUARDS CARRY BELT PACK STATIONS with headsets amp PLUG INTO WALL PLATES WHERE NEEDED INDUSTRIAL SECURITY INTERCOM SYSTEM RACK MOUNT SP
9. that channel in units where good sidetone null is impor tant e g where a gooseneck mic 18 applications Model PH 7 is a double muff high fidelity headset with very wide frequency response greater isola tion from ambient noise and extra rugged physical construction Clear Com s HS 6 telephone style handset has a dynamic mic and push to talk switch and is interchangeable with the above headsets Our Model PT 4 is a hand held push to talk mic for use with speaker stations All headsets and handsets have field replaceable cords An electret element gooseneck micro phone permanently mounted on the 58 412A is available as factory in stalled option speaker are used simultaneously this check should also be done for each of the station s sidetone null trimpots They are located directly behind the unmarked holes next to each talk tog gle switch The Stage Announce output should have the station operator s voice on it only while the front panel s 5 switch is engaged If any channels fed Program from the 58 412 the level to each channel may be adjusted using the trimpot s behind the access panel if any special functions have been set up be sure to verify their operation 111 OPERATION III A Quick Operation Guide Determine which main intercom lines are to be assigned to each channel Plug connecting cable into the appropriate XLR connectors on the rea
10. reduction in performance In situations where a significant current drain occurs 1000 feet or farther from the SB 412A an additional power supply or main station or an extra large gauge cable may be necessary to insure sufficient voltage for full output without clip ping Any number of Clear Com main stations and or power supplies may be connected in parallel In all cases multi pair shielded mic cable should be used to interconnect all stations The next Section describes cable requirements in detail Example f have 40 heodset stotions how many speaker stations can my system support Answer 12 speoker stotion equivalents S S E LE 8 RM 400A s 12 KB 111A s or combination of both See text for calculation 0 123 4 5 6 7 8 91011 12 13 14 15 16 17 18 19 20 SPEAKER STATION EQUIVALENTS 5 5 one or two channel station is 1 0 5 5 A four channel station is 1 5 S S E Maximum Number of Remote Stations 11 Cable Considerations The SB 412A contains one XLR type 3 pin male connector for each of the four main intercom channels and for each of the 12 switchboard lines total 16 output con nectors You ll route shielded cable from the rear panel of the SB 412A then connect it to all the remote stations in the system Allow 3 inches behind the unit for cables to extend from the rear panel Avoid sharp bends in cabling Depending upon your application you will run separate cables for ea
11. Position the unit near a source of 115 or 230 VAC power consumption 80 watts maximum 2 Use standard multi pair shielded ca ble described in Section IIB 3 Route all cables from the remote stations to the main station Use any 11 6 Set Up After connecting the SB 412A to the remote stations set the channel access talk presets and termination switches IMPORTANT Before turning on the unit be sure that the line voltage switch is correctly set and that the fuse is the proper rating 16 rate as the front panel extends only a very small amount beyond the top and bottom of the chassis See next page for mounting dimensions Before mounting the station insure that any special features you require have been set up 150 or operation or split feed headphones or all of the thee wiring methods de scribed in Section 110 Pin assign ments for the rear panel intercom XLR connectors are Pin 1 COMMON Pin 2 VDC Pin 3 INTERCOM AUDIO 4 Route cables away from heavy AC power sources such as lighting panels or electric motors uri in permanent installations cables should be installed in accordance with approved local building codes Next check that the program gain switch is set to match the level of the in going program mic or line level Finally adjust operating controls for desired operation and comfortable le vels 19 00 l MOUNTING DIMENSIONS Allow at least 5 5
12. S 410007 220 OHMS R12 Rit 410010 2 OHMS R1 0 R13 R43 410011 2 25 OHMS R110 R101 R92 R127 410013 4 7K OHMS RAS 410016 5 JON OHMS 24 R107 698 R89 R34 R R183 R182 F181 K149 RS R27 Kaa 32 4 Channel Main Module Assy cont d 410017 410018 410020 410021 410023 410024 410025 410928 410030 410051 410032 410033 410035 410935 410038 419939 410040 410041 310055 410058 419059 410063 410065 410065 410067 410071 410082 410034 419085 410088 410089 410096 410097 410104 479019 480000 480001 480004 480008 480012 480047 480056 480061 480069 480070 480073 510050 510057 560018 710160 ASSEMBLY 710160 F N 159027 170088 210132 410007 410013 470019 510039 RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES RES REV 10 nIO TRA TRA ICS TRA ICS TRA TRN AAA ICS SWT SUT TRN ASY CAE FCE AMP RES RES REV SWT CF 1 4M 5 15N OHMS CF 1 44 SX 22N OHMS 12 CF 174W 95 33 OHMS CF 1 44 5 47 OHMS 18 CF 1 46 5 S h OHMS 2 CF 1 4W 5 100r OHMS 17 CF 1 44 5 68N OHMS 4 CF 1 44 5 220k OHMS 6 CF 1 44 5 479 OHMS 1 4W 5X 12N OHMS 3 CF 174W 5 18 OHMS 10 CF izau 5 OHMS 1 CF 1 4W 5 1 85 OHMS 3 CF 1 44 5 6 58 OHHS 1 CF 1 44 5 82 OHMS 1 CF 1 44 57 47 OHMS CF 174W 5 2 74 OHMS 1 CF 1 4 5 1 2 OHM
13. auxiliary input on the rear panel allows an external program to be monitored at the station and or sent on one or more of the intercom chan nels Its preamp gain is switchable for or line level inputs An external speaker jack is also provided Special functions allowing 150 and IFB may be set up with internal jumpers See Section 111 for a detailed discussion of all controls and jumpers 11 INSTALLATION II A Maximum Number of Stations 58 412 has a maximum output current capacity of two amps the total current draw all channels cannot exceed this output The maximum number of remote stations that one 58 412 will support depends upon three factors 1 the current requirements of each remote station 2 the cable length 3 the cable gauge If your system includes headset stations only the SB 412A can operate a maximum of 100 units If your system contains speaker stations only the SB 412A can operate up to 20 units note if all remote stations are RM 400A s the maxi mum capacity is 13 If your system contains a combination of headset and speaker stations typical of most appli cations you must determine the maximum system capacity HEADSET STATIONS Consult the graph below Match the num ber of speaker stations in your system to the number of headset stations lf the point reached falls within the shaded section of the graph one S8 412A will operate the entire system with no
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15. 172 R103 R112 R94 R129 R205 R203 165 R164 R162 R148 R74 R B R21 6189 188 167 5155 R143 Ri l RB KIO R131 R122 R105 R96 R18 R17 R7 R58 R9 R47 R85 R79 R73 R67 R25 R22 R204 R8 55 6148 R141 134 R125 108 R99 APO R24 R93 R195 R23 28 R72 Ros R16 147 140 6135 54 R14 R88 R7o 70 R2 R63 R62 Kad R28 F130 95 R121 6104 R39 R290 R26 42 145 R139 K140 153 K106 97 F3O K123 R81 R 5 R111 R102 R93 R55 RIS 7 R15 F4 F3 37 136 035 033 132 231 030 128 127 626 025 024 G22 D21 020 119 018 1017 815 1012 011 1090 19 7 DS HS 14 03 D2 k s 848 ni 038 07 QA AS 012 011 010 09 163 018 017 016 015 014 013 na 03 168 1 8 1064 IC 01 IC 165 55 53 56 57 58 59 T1 REF DESIG C103 C104 C102 101 J101 R203 R201 R207 K205 R204 F202 R208 206 Pioa 103 101 6102 6101 1 6 Component Locations Remove R 9 for split feed JP 1 installed in units x with gooseneck mic Option page 24 2 Add one 47k ohm resistor to each IFB channel in addition to the diode page 24 Add one diode 1N 4148 type to each ISO or IFB channel page 23 A 35904 MOW MANS awy 357 NOMLYH3IAD AOT 2 NO GALNHOW 383 JNN 031109 JASNI 5
16. 2 MIC HOT PIN 3 EAR ELEMENT COMMON PIN 4 EAR ELEMENT HOT While using the 58 412 do not position the headsets within two feet of an AC power transformer the mics may pick up hum If the optional gooseneck mic 1 is installed it is controlled by the MIC ON OFF switch The HEADSET VOLUME 4 and SPEAKER VOL UME 5 controls permit independent adjustment of the intercom audio tevel the station s headset and external speaker outputs If using an external Speaker connect it via the rear panel jack 30 The front panel SPEAKER ON OFF switch 6 allows the external speaker to be muted instantly without disturbing its volume setting Programming Channel Access The set of recessed DIP switches that are labelled Talk 8 allows each channel s INTERCOM SELECT button 9 to be programmed for Talk access as well as the usual Listen access that button controls These switches are set OFF at the factory so that Talk access is normally controlled only by TALK toggle switch 10 If the operator requires both Talk and Listen access when the Intercom Select button is engaged set the talk pre sets ON for the channel s desired Channel Access SB 412A operator accesses the de sired main channel s by using the In tercom Select and Talk toggle switches Each channel s Intercom Select switch is push on push off illuminated switch It Tights dimly while engaged brightly when Call signal is recei
17. 412 SE 412A SWITCHEOARD REU A F N DESCRIFTION 180000 TRN FILTER CHOKE 15MH CARSON 6450 210046 AMP 7 FIN MTA HOUSING 640440 7 210048 AMF 12 FIN HOUSING 1 640440 2 210062 AMF 4 FIN MTA HOUSING 640440 4 210066 5 FIN HT HOUSING 640440 5 210082 TER CRIMF SLIF ON 187 IN AHF 6409465 1 210117 AMF 6 FIN MTA HOUSING AMF 640440 6 250264 3 1 2 IN RACK CHASSIS REVISED 250265 MET 3 1 2 IN RACK COVER 280030 HIS INS STANDOFF 1 4 DIA 1 41N LONG FOR 4 SCREW 280103 ROS SUFFORT RICHCOS LCRSB 4 HA 280115 HOS CHASSIS WIRE TIE 350A 710044 ASY 1 2 REG FOYER SUFFLY MODULE REV E 710159 ASY REVISED 4 CHAN MAIN MODULE ASSY 720043 ASY SR 412A FRONT FANEL 720046 ASSY SB 412A REAR FANEL 735006 ASY HARNESS REVISED 4CH Ji J3 J4 735008 ASY HARNESS REVISED 4CH SR 412A 735010 ASY HARNESS J 8 413 810023 SE 412 INSTRUCTION MANUAL gt 2 lt lt e 4 E Dy p ASSEMBLY 710159 ASY REVISED 4 CHAN MAIN MODULE ASSY DESCRIFT ON GTY REF DESIG 50002 zl CAE IUF ELECTROLYTIC SOV 14 C74 75 C54 C46 Cs C16 cri 82 C77 97 95 C20 62 C84 C19 C i ce 25 C C23 C26 C33 cio2 C24 C465 C34 C100 C80 C75 C70 Cis C53 C78 C29 ces C27 css C45 C44 CI C33 2 CBL C76 C71 C1 4 CSO C83 150005
18. 50 channel add a diode 1N4148 type to the pin sockets for D30 032 034 or 036 which correspond to the channels 8 C and D IFB operation cueing Talent audio cueing tercom tion to operation used extensively for causes muting of program and simultaneously switches the station s Talk feed for the in to the IFB channel s In addi jumpers in the SB h12A IFB requires a PIC 4 which sup ports up to four separate IFB channels active Like 150 the circuitry is only while the designated channel s Talk toggle is switched to the momentary ON position The PIC 4 mutes the program audio in response to the signalling voltage that the IFB circuitry sends on the FB channel Converting a channel to operation requires two jumpers 47k chm resistor 1 4 or 1 8 watt for the pin sockets of R136 R143 R150 or R157 corresponding to channels A B C and D AND the diode listed above in the 150 conversion procedure The cther special feature that involves an internal jumper is split feed for the headsets program in one ear inter com the other In most systems the program and intercom audio are combined in both the headset and speaker outputs By removing the 220k ohm resistor from the pin sockets for R9 you prevent program audio from being part of the intercom headset output Next connect the program headset output the white brown wire coiled up near the front panel to Pin 4 o
19. Com Concept Clear Com is closed circuit intercom system that consistently provides high Clarity two way communications in high noise and low noise environments A basic system consists of a single multi channel power supply or main sta tion connected to various single or multi channel remote stations Clear Com manufactures a wide variety of both portable and fixed installation units 11 compatible with each other Clear Com can also interface with other communication systems see Section 110 or ask your dealer for details Clear Com stations are interconnected with two conductor shielded microphone cable using 3 pin XLR connectors One wire carries the DC power 28 30 volts from main station or power supply to all remote stations and the other wire carries audio information The shield acts as a common ground Only one ter mination is needed throughout the inter com network and is located in a main station or power supply Clear Com is distributed amplifier system each main and remote station houses its own mic preamplifier for headset or speaker and signalling cir cuitry The Automatic Headset Detection Circuit shuts off when any station s mic preamp is disconnected so background noise on the line is not increased by an unused yet on line station Low impe dance mic input lines 200 ohms and specially designed circuitry make Clear Com channels virtually immune to RFI and dimmer noi
20. EAKER STATION RACK MOUNT QPEAKER STATION T3 Push to Talk 4831NI OML MOL OV eur adAy 092141 115 OL q p ES YON HLOOH GAONNONNY NOLVIS 13SGY3H LINDON TIVA 0 15 LONIY T3NNVHI YNOS YOOr gt WILI 3NIOWTAL NOUVIS ONAY 3NNYHO 8n03 VOOY WaHLSAS 141 IN TN 7 SOIHdV I D q p X2Yd qp NOLLVLS 31034 T3NNYHI YNOS WM 10 1 09 L NOWVLS 5 1 VOCL Wd 015 JOMLNOO OCIA 1138 XS HOLOWNIG OQNILHDIT UYU NVA Z 2 gt Q re E NOLVHSdO AK Wood v _ WVO NOU V1S ONIY 13 3 vOOYT W3 TVOINHOS IL Oranv WOA 11 Mounting SB 412A SB 412A is designed to mount in a standard 19 rack using 3 5 vertical ly It can also mount in a console or sit atop a shelf if necessary The station extends 9 back from the front panel but avoid sharp bends in cabling and allow additional 3 behind the unit If mounting the station in a console the cut out must be very accu Station Connection Once you determine the configuration of your intercom system decide upon a location for the main station Then 1
21. OFF 5 78 25 4 40 HEX MACHINE SCREW BLACK 5 16X4 40 HEAD NYLON SCREW FANEL MTG SQUARE RED LEM GEN INST amp CMF 4 8 REZEL SET FOR 390010 G I HF55 4 BED CF 1 44 5 3 9K OHMS CF 1 4W 5 220k OHMS REV 100K LINEAR MTG CTS F 6645 POWER ILLUM ROCKER A RCOL 1403ACBER2 MINI TOG W LONG LEADS 2012 5613 SUT SNAF ACTION C amp h 812148025REIUS SNAF ACTION 822iYAU2 1 6 A CAT BAR 0051 11 0572 MATRIX SWITCH MODULE W O 150 MATRIX CIRCUIT MODULE REV H 720046 ASSY SB 412 PANEL REV A AAA Suc TER TER TER TER HET RES RES RES SUT SWT FUS FUS AAA CHL STR SUC SF CONNECTOR SUC 3M CONNECTOR JACK FOR SFEANEH EXT U SUITCH H112A WIRE NUT FOR 22 GUAGE WIRE HOL NP S115 CRIMF SLIF ON 187 IN AMF 6409446 1 CRIMF SFALE LUG 40811 1 CRIMF SLIF ON 25 AMF4 640932 1 5 412 KEAR PANEL 1 44 5 47K OHMS CF 1 4W 5 680 OHMS CF 1 4W 5 560 OHMS DFBT SLIDE SUT SCRFT 45625S6LFF LINE ULT SELECT SLIDE SW CHASSIS MTG SUCRFT S6206L1 3AG 1 AMF SLOW BLOW 313001 SQ REZEL FUSEHOLI IER MOUSER 44FH113 FOWER XFORHER CARSONt BA3J2 CORE SET 3 CONTDI BELDEN 12237 SR SF 4 QTY DO FJ re p D b GI UI EQ FJ eta b 19 FJ lt hd ee GL o ay ker t ASSEMBLY 58
22. S 4 CF 44 57 1 54 OHMS 5 CF 1 44 57 1 MEGAOHM 5 CF 1 4W 5 10 CF 1 84 1X 6 81 OHHS CF 1 24 95 22 OHMS CF 1 20 5 10 OHMS CF 174W 52 1 5 CF 1 48 5 100 OHMS CF 1 24 5 370 OHAS CF 174W 5 43 5 CF 1 8U 1 2 67M OHMS CF 178W 1 20 0 OHMS 1 8 1X 10K OHMS CF SZ 1 4 820 CF 1 40 SZ 240N OHMS CF 1 44 SZ 3 0h OHAS SON TRIM FO V MTG FI EREFT 10H 5Oh NN ee 1N4148 SIGNAL DIODE 3 144001 RECTIFIER DIODE 1 MFS 13 TRANSISTOR 4 MFS 63 TRANSISTOR 4 LH3B4 IC FOWER AMF 14 FIN 1 2N4401 NFN TRANSISTOR 8 RC4SS9NRB DUAL OF 5 245486 CHANNEL JFET 1 2NS639 CHANNEL JFET 1 ICS NES532 DUAL LO NOISE OF ANF 2 DG3O8A ANALOG SWITCH QUAL t SCHEF N 00 3U EE N 21 01 145 01 B AG 3 03 4 SFUT 2019 612 319 REV THROW 4 amp 00CT 600CT MAGNETICS 108 1 REVISED 4 CHAN ALJUST ASSY REV 6 1 5 1006 ELECTROLYTIC 169 R L 4 REVISED 4 CH SERIES ADJUSTMENT 1 20 PIN HEADER 1 87563 0 1 CF 1 48 5 220 OHMS 4 CF 1 4M 5 4 7 OHMS 4 SOK TRIM MIG 10 50 4 MINI FIANO DIF SUITCH GRAYHILL 76 5 04 ASY REVISED 4 CHAN ADJUST ASSY SEV A R171 158 Rist 144 RI37 R202 R3 R32 R40 R35 R199 126 R109 R100 R91 R57 R31 R36 R29 R201 R198 R27 R71 R159 R156 R152 R149 145 R142 R138 R135 R157 R150 R143 R136 F
23. ain many stations along interconnect path Or you can use Clear Com s line splitter one input three outputs to feed individual lines to station inputs see diagrams on the following pages for various configurations Daisy chaining and line splitting decrease the amount of cable required and simplify installa tion PERMANENT INSTALLATION CABLE We recommend you use vinyl insulated and jacketed cable for connections to perma nently installed stations it costs less and is easier to pull through conduit than the rubber insulated cable You must use low capacitance cable We suggest you try BELDEN 8762 20 gauge stranded for applications up to 500 feet and BELDEN 8760 18 gauge stran ded for up to 5000 feet If conduit is available when installing permanent remote stations run intercon nect cables through the conduit to each wall or console mounted unit NOTE chassis ground and signal ground XLR connector Pin 1 are NOT the same point DO NOT connect the chassis to Pin 1 The chassis is insulated from the signal ground with a capacitor 01 microfarad 1 4 This eliminates the hum potential shock hazard that can arise if stations are at different ground potential In some situations existing wire in a conduit may be used consult the factory for guidelines where conduit is NOT used and equipment doesn t share a common ground it is good engineering practice to run an additional g
24. arding operation modifica tions applications of your intercom system call us during business hours at 415 861 6666 Pacific Standard Time IV C Troubleshootin Symptom Cause Remedy System non operable power switch not lit Circuit breaker trips repeatediy short circuit LED remains lit Hum or buzz i system Excessive background noise pick up by mic A B loss of AC power or internal fuse is blown could be caused by power supply failure shorted or mis wired cabling defective remote station inductive pick up caused by close proximity of main or remote station to power lines or transformers ground Joop caused by improper ground of system 10 ohm chassis ground resistor R14 in power supply is open inductive pick up by headset mic check by switching mic on and off distance from mic to lips is too far volume too high too many mics on in system CONTINUED plug unit into dependable AC source replace fuse if it blows repeatedly bridge rectifier or other component probably shorted inside power supply Have power supply fixed remove cables one at a time from main station until faulty line is located for shorts between Pins check remote units relocate offending unit reverse power cord lift ground see Section 11 check resistance between chassis and Pin 1 of conn ector it should be 10 ohms If not open power supply and replace resis
25. cabling all stations beyond the break are disabled this problem is solved by the loop through shown in Method 2 fee 999 Loop Through Method 2 provides another advantage in that the DC resistance accu mulated in the cable is no more than half as great as in the standard daisy chain arrangement However it also results in a cumulative cable capacitance which may be twice as great as Method I s D GP i 88 HEB O BBB HI Hub This hub method is especially useful for belt packs and situations in which running two cables to the remote stations is cumbersome The hub method usually results in fairly low cable resistance between stations but cumulative capacitance is often the highest of the three methods cS WHLSAS CHXIW Vole 8S D 5 ATWOIAIONI 6228 318 2 30138 00 29 8 f 318vO N3q138 ale 214 001 583 001 54 0 9 51 V1LL B IVOIdAL Q3013lHS Z 3719792 N30138 4 201 signalling Configurations in Multi Channel Systems In normal circumstances the CALL light on a two channel remote station lights only when someone signals on the channel that station has selec ted for communication This is because the Visual Signal travels on the audio line in the form o
26. ch chan nel going to the single channel remote stations or two channels combina tion together to two channel remote stations crosstalk considerations dis cussed later in this section When choosing interconnect cable keep the following considerations in mind 1 DC resistance of the ground or common conductor affects crosstalk n per manent installations do not use wire smaller than 20 gauge stranded ex cept runs shorter than 100 feet Keep the total resistance of the ground under 2 ohms 2 The capacitance of the interconnect Cable affects the frequency response and sidetone stabilty Total capaci tance should not be greater than 25 microfarads capacitance between con ductor and shield equivalent to an intercom system containing 5000 feet of cable at 50 pF per foot 3 Clear Com Systems operate best with cable that has no more than 35 pF from conductor to conductor and no more than 70 pF from conductor to shield PORTABLE INSTALLATION CABLE Typical cable for portable system inter connection is rubber jacketed two con ductor shielded microphone cable We suggest you try BELDEN 8413 24 gauge stranded for connections totalling 500 feet or less and BELDEN 8412 20 gauge stranded for connections running from 500 to 5000 feet 4 Portable remote stations such belt packs each have a pair of input and out put connectors when installing a system that includes these you can daisy ch
27. e AC power to the station an integral neon bulb indicates when the unit is on The circuit breaker 24 protects against DC power shorts Any current load greater than two amperes will cause it to trip causing the short indicator 25 to light After removing the short pres sing the breaker button instantly stores normal operation The AC line voltage select switch 26 and external line fuse 27 permit in stant change the field between 115 CHANNEL ASSIGNMENT NOTES Channel A Channel C and 230 VAC operation certain to use the correct slow blow fuse 115VAC 1A 230 0 5A Channel Channel 0 111 Special Features 150 Split Feed Headset Operation Refer to the printed circuit board dia gram page 30 for jumper locations 58 412 similar to the RM 400A and MS 400A provides you with the capabili ty to convert any one or more of its channels from regular two way operation to either 150 or IFB operation simply by adding one or two jumpers the selected channel s circuitry The channel 150 function is engaged only while the channel s Talk toggle is the momentary ON position Channel 150 causes the 58 412 operator s voice feed to all other channeis to be inter rupted except those also in the momen tary ON position so the operator may talk with the selected channel isolated from the rest of the system To set up an 1
28. e audio channel PNP darlington 09 channel A s line circuit operated as a current source to prevent line loading when its base circuit is pulled low The resulting voltage on the intercom line is sensed by the NPN darlington Q5 and its corresponding element all other line circuits con nected to this channel Collector current through the forward biased NPN transistor causes the lamp to light IV B Maintance amp Warranty Clear Com s solid state intercoms power supplies and interfaces are designed with a modular building block approach for easy system expansion and field servicing Our chassis design incorpor ates highly efficient ventilation and conservatively engineered circuitry assuring years of trouble free service Our packaging is the most rugged avail able constructed from 16 gauge aluminum or stainless steel glass epoxy plug in PC Boards Clear Com is heavily shield ed against hum RFI pick up and solid state dimmer SCR noise All Clear Com stations are compatible 26 Before shipping we test each unit to make sure it meets or exceeds all speci fications All units are guaranteed by Clear Com against defects in materials and workmanship for one year following date of purchase 90 days for headsets see warranty enclosed with each unit Our Engineering and Serice Departments will gladly provide you with technical advice and assistance if you have any questions reg
29. f 6 pin XLR insert which you substitute for the standard 4 pin one Connect the inter com headset output to Pin 5 Pins 3 and 6 are circuit common program will be in the left ear the intercom will be in the right See diagram below for the wiring detail of the connector IOO pF IKV HEADSET CONNECTOR 6 PIN INSERT WIRING SIDE 24 TECHNICAL INFORMATION IV A Circuit Description There are two inputs to the main mic preamp one for each headset connector The input from the upper connector is switched is also used for the opt ional gooseneck mic The two inputs are routed to the summing input of the preamp 1 2 pin 2 via J3 pins 5 amp 6 compressor circuit 01 reduces the gain nominally 451 dB with a 55 dBv input as necessary to maintain an output level near 0 dB The talk signal branches to three sections the talk buss which feeds the station operator s voice to the intercom channels the S A stage or set announce circuit and the side path which bypasses the intercom chan nels to feed the operator s voice di rectly to the station s headset speaker output sidetone The feed from the talk buss to the tercom channels is controlled by a four section analog switch 1 5 Each chan nel s talk access may be turned by engaging that channel s Intercom Select button if its talk pre set is on or by using the talk toggle associated with that cha
30. f DC voltage A simple modification may be made to the the system wiring so that stations which are switched to one channel will respond to a call signal on the other channel This modification may be applied in both directions so that all stations will indicate a call signal from either channel white still maintaining two completely separate inter com channels diagram shows how Channel A can send signals to Channel 8 TWO CHANNEL cha MAIN STATION SUPPLY tne 010065 4 914 In Line Isolation In certain applications you may want to isolate conversations in one section of the system Clear Com offers Model BA 1 n Line Isolator which blocks intercom audio while allowing DC voltage to flow to an isolated of the system The BA 1 allows one channel to support several simultaneous and inde pendent conversations The main station cannot communicate with the isolated legs of the system Private locai conversations can go on along a common interconnect line without adding great lengths of cable e or additional main stations You may incorporate any number of 1 Isolator s as long as the capacity of the main station is not exceeded by added remote stations There are a variety of ways to incorporate the BA 1 into a system For instance you can plug the BA 1 directly into a remote station s exten 5 sion output connector main station s channel output co
31. icate with up to four other people or groups of people and be able to quickly change any remote station s channel assignment from the front panel The SB 412A s four main intercom chan nels can be accessed either individually or simultaneously while still maintain ing isolation between channels Access to the four main channels is controlled by the row of pushbutton and toggle switches along the bottom right side of the front panel Separate con trols for talk and listen for each chan nel enhance the station s versatility The twelve switchboard inputs are indi vidually assigned to of the four main channels or to an isolated OFF po sition via the matrix switches on the left half of the front panel Controls which affect the input and output at the station mic headsets speaker and program are located in a row along the upper right of the front panel Controls that are recessed be hind the front panel are normally used only during installation and set up The SB 412A is self powered and also power up to 20 speaker stations or 100 headset stations it is normally used as a main station which provides system termination at a central loca tion but may be used also as a remote station that provides extra power capa city On the SB 412A rear panel XLR con nector for each of the four channels and the twelve switchboard inputs allows easy connection to the rest of the sys tem program
32. ine 3748 HEADPHONE AMP SPEAKER AMP Load Impedance 50 2000 ohms Load Impedance 8 50 ohms 16 preferred Output Level at least 20dBv Output Level 4 watts max into 8 ohms across 600 ohms Distortion 0 52 THD at 2 Distortion 0 22 THD at 1kHz Freq Response 200 Hz 15 kHz 298 Freq Response 150 Hz 18 kHz 2dB Gain from Intercom Line 41dB Gain from intercom Line 37dB AUXILIARY PROGRAM AMP Gain to Intercom Line switchable 44548 mic 548 line Input Impedance 3 6k ohm mic 300k ohm line both balanced Nominal Input Level 65 mic 10dBv line Frequency Response 150 Hz 18 kHz 2dB Gain to Headset Speaker 7848 POWER SUPPLY Output Voltage 30 volts regulated with electronic overvoltage protection Output Current 2 amperes maximum circuit breaker protected with electronic short circuit current limiting Hum amp Noise 1mV Capacity 100 headset or 20 speaker stations CONNECTORS Headset two 4 pin male XLR Intercom Lines four 3 pin male XLR Switchboard twelve 3 pin male XLR Program Input 3 pin female XLR S A Output 3 pin male XLR SYSTEM OPERATING CONDITIONS Maximum Distance 1000 feet from terminating station to maintain all specifications using Belden 8778 cable System Level 15dBv nominal OdBv max STATION OPERATION Channel Separation 25048 Line Impedance terminating 200 ohms or Signal to Noise 2 6048 bridging 15k ohms 200 10k Hz sw
33. ing four pair cable between multi channel stations atl the shields and ground wires should be connected effectively lowering ground resistance and reducing crosstalk Refer to the diagram on pages 6 amp 9 Also tie unused wires in your interconnect cable to ground Pin 1 thereby further reducing crosstalk 11 0 System Wiring Both physical and electrical considera results ina loss of sidetone null tions are involved in determining the remote stations some level loss best system wiring configuration The remote stations to the station physical aspects center around ease of reduced headset speaker output wiring whereas the electrical aspects clipping and in the ground conductor are dictated by performance requirements a serious increase in crosstalk of the entire system and or particular Stations in the system The two main Build up of capacitance results in electrical considerations for the cable duced sidetone null at all stations are resistance in the conductors and the line s in question and reduced capacitance between the conductors voice clarity due to excessive frequency roll off Build up of resistance in the cable There are three main methods of configuring your system wiring ANY combination of them can be used one system Daisy Chain This daisy chain method requires the least amount of cable but may be impractical because of your facility s physical layout Also if a break occurs in
34. it Visual Signal Send call button sends signal only on lines with monitor switch engaged Minimum output 11 Visual Signal Receive independent of switch settings Minimum sensitivity 4V0C AC POWER REQUIREMENTS DIMENSIONS 105 130VAC 210 260 VAC 48 62 H2 19 W x 3 5 H x 9 D 80 watts maximum 483mm x 89mm x 231mm dBv is referenced to 0 775 volts rms 30 IV E Parts Lists ASSEMBLY 720043 150048 210013 240007 240015 240020 240024 250249 250252 250261 280053 280054 280067 280098 280099 280100 280101 390010 390011 410012 410028 470020 510002 910006 410028 510041 520028 710095 710098 ASSEMBLY 210002 210003 210055 210067 210082 210088 210089 250256 410021 410044 410046 510053 510065 520021 520027 560011 610000 640004 CAL AAA HAN AAA KNE MET MET HIS HTS KIS HIS HES HIS HES LED BEZ RES RES AAA SWT SUT AAA SWT ASY ASY ASY SE 412A FRONT PANEL REV A 5 100PF 1 9 20 FF SWC CONNECTOR PANEL HANDLE 2 INCH SMITH 1618 ROGANSRB 67 0 DC ML 125 1 2 W 1 8 SHAFT RED BUTTON C amp K SWITCH 8121 58 412 SWITCH KNOB GREY WITH 510030 58 412 FRONT FANEL HORZ MS 400A RM 400A SE 412A ACCESS FLATE BRACKET 4CH ADJ SUFFORT GROMMET HARTWELL HN3G 31 1 FLUNGER HARTWELL HN3F 31 4 1 DRESS CONE NUT C amp K 7025 1X1 4 INCH NYLON SPACER SMITH 4062 374 1 4 HEX NYLON STAND
35. level or line levei Program auxiliary preamp switch located on the rear panel 17 sets the circuit s input sensitivity so that either mic 50dBv line 0dBv level signal will produce full station output The input accessed from a rear panel 3 XLR connector 22 is balanced but may be used single ended if you tie one of the inputs to circuit common Program audio from the preamp feeds to the Pro gram buss for sending onto the intercom lines and to the station s headset and speaker amplifiers Program feed to each intercom line is controlled by individual trimpots 18 behind the ac cess plate The trimpots are set fully OFF at the factory The program level heard in the station s headset speaker is set by the front panel PROGRAM VOLUME control 19 Call Signalling Pressing the CALL button 20 causes the visual signalling voltage to be sent onto the intercom lines of only those channels whose Intercom Select buttons are engaged This voltage is sensed by all stations those channels inclu ding the sending station which cause the corresponding CALL LAMPS 21 to light brightly A signal from another station is indicated in the same manner whether not the Intercom Select but ton is engaged Individual LED s 7 above each of the switchboard assignment levers indicate an incoming call on any switchboard line s even those the OFF position Power The power switch 23 controls th
36. me if necessary If applicable adjust the program level to the station s headsets speaker using the PROGRAM volume control set the level to the intercom lines with the individual trimpots behind the access panel Check the SIGNALLING functions on each channel Check operation of any special features and functions needed See Section IIIC to set up 150 or IFB access operation or SPLIT FEED headset 20 81 126 01 Gt 14023 45 NO N POE E 9 N jaued 1294Y 45 Zt 111 SB 412A Operation The controls on the surface of the front panel are used during normal operation of the station the controls that are recessed behind the front panel cover plate are normally needed only during station set up In the following explanation of con trots the boldface numbers paren theses refer to the diagram of the SB 412A on page 18 The SB 412A has two headset connectors 1 2 the mic input of the upper connector is switched by the MIC ON OFF switch 3 located to its left When neither headset jack is used the mic preamp s gain automatically drops to near unity to avoid noise pick up from the unused input The gain of the switched mic input may be lowered removing either R 15 3 dB or R 14 5 dB DO NOT remove both The headset connector pin out is PIN 1 MIC COMMON PIN
37. nnector or between two runs of cable on any channel This diagram illustrates two ways of isolating any section of your system MAIN STATION SOLATOR BA 1 ISOLATOR e e 10 Interfacing With Other Systems Clear Com s Model AC 10K Universal interface Model AC 10H Telephone Interface Model IFh 8 TV Camera Interface and Model TW 12 Two Wire System Interface allow you to link with virtually any type of communications system When your existing system is upgraded with Clear Com equipment you may continue to use portions of the older system AC 10K and AC 10H are called Adapt a Com s and guarantee compatibility with any in house intercoms and other two three and The AC 10H facilitates on line communication via standard telephones and helps you directly communicate with remote locations using two wire or four wire dedicated TELCO pairs four wire systems 12 Typical Four Channel Intercom Systems The diagram on the next page shows standard Clear Com systems for typical applications Since your requirements are likely to differ both the wiring and your choice of stations may vary SYMBOL KEY Four channel speaker station rack mount RM 400A Two channel speaker station wall mount KB 111A KB 112 Two channel speaker station rack mount RM 120A Two channel headset station wall mount MR 102A One or two channel belt pack CP 100 CP 300 RS 100A 85 201
38. nnel Following the signal path trough Channel A s line circuit the station operator s voice is fed to the intercom line through the line driver while IC6b maintains high impedance to prevent line loading and amplifies signals the line to feed the listen buss A portion of the talk signal is fed directly to the line buf fer through to allow the talk signal to be nulled out at the listen side The output from the line buffer is switched to the listen buss directly by contacts the Intercom Select switch S2 Signals from the selected chan nels are combined in the summing ampli fier ICha which also mixes in side tone via P6 feeding the combined output to the headset driver via P8 and the speaker amp via P7 A signal on the program or auxiliary input is amplified by configured as a differential or balanced input amp For single ended unbalanced use the signal is applied to one of the input terminals and the other is groun ded This output branches to the pro gram buss for feeding to the intercom lines as set by each channeis trimpot P101 104 on the adjustment module and directly to the headset and speaker amps via P5 An extra headset driver permits program and intercom in separate sides of a binaural headset yet program and intercom are always combined in the speaker output The visual signalling circuits utilize a DC voltage momentarily impressed on th
39. on any of the station s other functions Sidetone Sidetone the voice of the operator heard his her own station must be carefully controlled to avoid acoustic feedback and or system instability The SB 412A has a front panel SIDETONE trol 14 to add set amount of side tone to the unit s headset speaker out puts independent of any channel s that the operator is monitoring Each channel s SIDETONE NULL this is located behind the hole 15 beside each Talk toggle switch is set at the factory for best full null with less than 500 feet of connected cable Because of the con trolled amount of added sidetone the number of channels being monitored doesn t have much effect on the overall sidetone level ad justment unmarked When you are using a gooseneck mic with an external speaker it s usually neces sary to turn the sidetone control all the way down counter clockwise to pre vent acoustic feedback Depending upon the relative positions of the mic and speaker it may also be helpful to ena ble the dipper circuit which helps prevent feedback This automatically attentuates the station s speaker output when any of the Talk toggle switches are in the momentary ON position Termination The termination switches 16 are set only during installation and must NOT be changed unless a change in system wiring requires it 22 Program Input The SB 412A has Clear Com s new switcha ble mic
40. r panel Route cables from 58 412 to remote locations and connect it to the inputs of the remote stations Repeat Step for the switchboard inputs Remember that each switchboard input is internally terminated by the 58 412 So if any switchboard lines connect to another station or power supply switch OFF the termination at that station If program monitoring is desired connect the program source to the PROGRAM input the SB 412A rear panel and set the gain switch to match the source level Connect a paging amp to the STAGE ANNOUNCE output if used Connect a monitor speaker 16 ohms is ideal is to the EXTERNAL SPEAKER output if used Be sure that the rear panel MAINS SELECT switch and fuse correct for the AC power you re using then connect the power cord and turn on the POWER switch the switch will light up Determine the access methods required for each channel and set the appropriate DIP switches Check the settings of the termination DIP switches and be sure that each chan nel of every station the system is connected to and only one TERMINATION Plug in the headset or turn on the mic and speaker turn the SIDETONE volume up to the 10 o clock position then carefully adjust the HEADSET or SPEAKER volume for a comfortable level without feedback Enable communication with each channel using the TALK toggle and or INTERCOM SELECT switches and re adjust the headset or speaker volu
41. round wire to tie all chassis together this decreases susceptibility to noise fields In installations continued electrical 4 If you don t use Belden cable use similar type with wire gauges capacitance as specified in this manual The conductors in the cable especially in longer runs over 500 feet must have low DC resistance less than 15 ohms per 1000 feet large diameter conductors and low capacitance less than or equal to 55 pF per foot of cable capacitance between conductor and shield Refer to the Belden wire specs on page 6 to ensure that your substitute cable is comparable MULTI CHANNEL CABLE CONSIDERATIONS When installing a system that includes multi channel stations the channel feeds may be routed individually to each station with separate two conductor shielded cables OR four channel feeds may be routed together with one four pair shielded cable such as BELDEN 8725 see multi channel cable connection diagram on page 6 Two channel feeds may be routed with a two pair shielded cable such as BELDEN 8723 Crosstalk When multiple channels are fed to remote stations the amount of crosstalk is proportional to the amount of DC resistance in the ground return Two ohms or less resistance is ideal two ohms will give you 40 dB of isolation Anything greater than two ohms will increase crosstalk Each channel must be fed in its own separate shield When connect
42. se Clear Com main stations power supplies and certain remote station each have an auxiliary program input with its own volume control which allows an external source to be fed to the intercom system Visual Signal Circuitry a standard feature on most main and remote sta tions allows the user to attract the attention of operators who have removed their headsets Depending upon the type of main and remote stations selected a maximum number of remote stations from 13 ali speaker stations to 100 all headset stations can be distributed along a mile of wire Remote stations bridge the intercom line at a very high impe dance and place a minimum load on the line Audio level always remains stant and does not fluctuate as sta tions leave or join the network 28 30 volts DC provided by main stations and power supply units enable remote stations to operate with minimal current 10 milliamperes quiescent for headset stations 20 mA quiescent for speaker stations while generating tremely loud listen volumes greater than 110 dB SPL The higher voltage and low current keep voltage losses to absolute minimum in long lines If the voltage drops due to the addition of great lengths of cable or many more stations Clear Com equipment will con tinue operating with tess than 12 volts available SB 412A Description SB 412A is designed for applications in which person needs to commun
43. tor move mic away from hum field or use carbon or electret headset move closer to mic turn down headset or speaker volume turn off all unused mics 28 Symptom Cause Feedback acoutical check sidetone levels check termination should be only one per channel volume too high at one station two or more speaker stations have mics on at once speak one at a time per channe speaker volume up too high at station with gooseneck mic eee eww wm ee we ee ew P ewww ewe we Power supply s 10 ohm resistor is opened when the system ground comes in contact wtih something with respect to the station s earth ground Should this occur we recommend you carefully check the system ground and AC distribution in the area NOTE This is a potentially dangerous situation if it occurs SHOCK HAZARD may occur between the ground and the metal boom of the headset IV D Specifications AMPLIFIER DESIGN IC amplifiers including solid state switching and signalling cir cuits Current limited and short circuit protected MICROPHONE PRE AMP Input 200 ohms nominal dynamic type Input Level 55dBv nominal 10dBv max Frequency Response 250 Hz 12 kHz contoured for clarity Limiter Range 25dB Gain Adjust 5dB Gain to Intercom L
44. ved It always switches the Listen path of its associated channel and depending on the setting of the Talk pre set will also switch the Talk path The Talk path may always be turned on with the Talk toggle switch which has both momentary and locking positions Switchboard Matrix The twelve assignment switches 28 let you assign the switchboard inputs 29 rear panel to any one of the four main intercom channels D or an isolated OFF position When switchboard inputs are assigned to the OFF position they are isolated from all other switchboard lines and isolated from the four main intercom channels The only links between the SB 412A op erator and the switchboard line s the OFF position are to the remotes via the All Page function described betow or from the remotes via the S 8 412A s call receive LED s Stage Announce The 58 412 operator presses the STAGE ANNOUNCE button 11 and audio from the B 412A s mic s feeds to the rear panel S A connector 12 Normally the Talk signals to the intercom lines are inter 21 rupted but you may add jumper across the switch to prevent this All Page When the ALL PAGE button 13 is pressed the 58 412 operator s voice is sent to all four intercom channels si multaneously whether or not chan nel s Talk access is It also feeds the twelve switchboard lines including those in the OFF position All Page has no effect
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