Mackie_SR40-8,_SR56-8_Service_Manual电路图.pdf

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1、SR408 SR568 SERVICE MANUAL VERSION 1.11997, 1999 MACKIE DESIGNS, INC. 820-176-00 RadioFans.CN 收音机爱 好者资料库 Page 3 is interactive Go To Bulletins CAUTION AVIS RISK OF ELECTRIC SHOCK DO NOT OPEN RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR CA UTION : TO R E DU C E THE RIS K O F ELE C TRIC S HO C K D O N O T

2、R E M O VE TH E C O V ER (O R B AC K) NO U S ER SE R VIC EA B LE PA R TS IN S ID E RE F ER SE R VIC IN G TO Q U ALIFIE D P E R S O N N E L W A RN ING : TO R E DU C E TH E R ISK OF FIRE OR E LEC TRIC S HO C K, D O N O T EXP O SE THIS PR O D UC T TO R AIN OR M O IS TU R E TO PR E V EN T ELE CTR IC S H

3、 O C K , D O NO T U S E THIS PO LAR IZE D PLU G W ITH AN EXTE NS IO N C OR D , R E CE P TAC LE O R O TH E R O U TLE T U NLE S S TH E BLA D E S CA N B E FU LLY IN S ER TE D TO P RE V E NT BLA D E E XP O SU R E . ATTE NTIO N: P O UR E VITE R LES RISQ UE S DE C HO C E LE CTRIQU E, NE PA S EN LE VE R LE

4、 CO UV E RC LE . A U CU N EN TR ETIE N DE P IE CE S IN TE RIE UR ES PAR LUS AG E R. C ON FIE R LE NTRETIE N AU P ER SO NN EL Q UA LIFIE . AV IS :P OU R EV ITER LES R IS Q U ES DINC EN DIE O U DELE CTRO CU TIO N, NE XP O S EZ PA S CE T ARTIC LE A LA PLUIE O U A LH UM IDITE . PO UR PR E VE N IR LE S C

5、 H O C S ELE CT RIQU ES N E PA S UTILISE R CE TTE FICH E PO LA RIS EE A VE C UN PR O LON G ATEU R , UN PR IS E D E CO UR AN T O U UN E A UTRE S O RTIE D E CO U RA NT, SA UF S I LE S LA M E S PE UV EN T E TR E INS ER EE S A FO ND SA NS LAISS ER A UC UN E PA RTIE A DE C O U V E R T. This apparatus doe

6、s not exceed the Class A/Class B (whichever is applicable) lim its for radio noise em issions from digital apparatus as set out in the radio interference regulations of the Canadian D epartm ent of Com m unications. ATTENTION :Le prsent appareil num rique nm et pas de bruits radiolectriques dpassant

7、 las lim ites applicables aux appareils num riques de class A/de class B (selon le cas) prescrites dans le rglem ent sur le brouillage radiolectrique dict par les m inistere des com m unications du Canada. This equipm ent has been tested and found to com ply with the lim its for a Class A digital de

8、vice, pursuant to part 15 of the FCC rules. These lim its are designed to provide reasonable protection against harm ful interference when the equipm ent is operated in a com m ercial environm ent. This equipm ent generates, uses, and can radiate radio energy and, if not installed properly and used

9、in accordance with the instruction m anual, m ay cause harm ful interference to radio com m unications. Operation of this equipm ent in a residential area is likely to cause harm ful interference in which case the user will be required to correct the interference at his own expense. The lightning fl

10、ash w ith arrow head symbol w ithin an equilateral triangle is intended to alert the user to the presence of uninsulated dangerous voltage w ithin the products enclosure, that may be of sufficient magnitude to constitude a risk of electric shock to persons. Le symbole clair avec point de flche linte

11、rieur dun triangle quilatral est utilis pour alerter lutilisateur de la prsence linterieur du coffret de vlotage dangereux non isole dampleur suffisante pour constituer un risque dlctrocution. The exclamation point w ithin an equilateral triangle is intended to alert the user to the presence of impo

12、rtant operating and maintenance (servicing) instructions in the literature accompanying the appliance. Le point dexclamation lintrieur dun triangle de la prsence dinstructions importantes pour le fonctionnement et lentretien (service) dans le livret dinstrucion accompagnant Lappareil. RadioFans.CN 收

13、音机爱 好者资料库 CONTENTS INTRODUCTION.4 TECHNICAL SUPPORT. 4 DISCLAIMER . 4 SYSTEM OVERVIEW .5 THE SR408 IN A NUTSHELL. 5 MATRIX . 5 STAGE MONITORS 1 OF 56, SR56-8) MAIN AUX RETURN (1 OF 4) B AUX RETURNS (4 TOTAL) that is, they alternate. D11 couples the LCR-MUTE line to U2D, ensuring that the RSL is exti

14、nguished when nothing is soloed (the resting state for U1A and U1B is low, which would allow the RSL to be on). D8 couples the IP-SOLO line to the input to the SOLO-CNTL-OP comparators. Since U1D acts as a current-sink, it (via D8) prevents the output solo comparators from functioning any time that

15、SOLO-CNTL-OP is present. This means that inputs have precedence over outputs in the solo system; if an output is soloed, and the user solos any input, that input will be heard, and the output solo muted. The corresponding output solo LED is extinguished during this time. 18 CLEAR COM INTERFACE The C

16、lear Com production intercom system is the de-facto standard within the music industry. The SR408 has an integral Clear Com interface that emulates a standard belt pack and ties it into the consoles headphone system. To use it, you use the consoles talkback microphone and the solo system headphones.

17、 The interface provides the standard Clear Com beltpack features: call button, call light, receive level control, and push-to-talk switch. Of course, like any Mackie product, theres some new thinking going on to make your life easier. One major problem for any intercom system is the possibility of a

18、 ground loop between the audio consoles ground system and whatever ground the production intercom system is using. In many situations, the stage lighting company provides the intercom. In this case, the intercom system ground is most likely the same as the dimmer racks (nasty, really nasty). It is b

19、est if this ground not come in contact with the audio consoles ground. The SR408s Clear Com interface uses an isolation transformer to keep the two ground systems completely separate. There is no possibility of a ground loop regardless of who supplies the intercom system and where they get their gro

20、und from. CIRCUIT DESCRIPTION (Refer to the MASTER PCB schematic.) The Clear Com intercom system uses a standard microphone cable as its means of interconnection. Signal levels are low enough that the system can use a spare mic line in the microphone snake. The three wires of the mic cable are used

21、for: pin 1 - ground, pin 2 - 28V dc power, pin 3 audio. This is a party-line intercom system since all talkers and all listeners share the same line. All stations are connected in parallel. The DC voltage on pin 2 supplies power for the entire system. Any station can talk and any station can listen.

22、 The system uses a low voltage DC signal applied to the audio line for signaling. A simple darlington transistor switch monitors the DC conditions on the line and turns on a light bulb when it detects a call signal. One other competing intercom system, pioneered by RTS Systems (now a division of Tel

23、ex), uses a balanced line for the audio signal with the audio modulated onto the power supply voltage. Ultrasonic tones provide addressable signaling. This system has found a home within the broadcast and video production fields. The two systems are not compatible without use of a special interface

24、system. 19 TRANSMIT SIGNAL PATH The transmit signal path begins at the talkback microphone. The intercom interface takes the line level signal at U1705A and sends it to the intercom sub-system via JP1704 and JP1803. Analog switch U1801A passes the transmit audio when the INTERCOM button has been pre

25、ssed. U1802A buffers the analog switch output and U1802B operates as a bi- directional current source that drives the intercom line via isolation transformer T1801. RECEIVE SIGNAL PATH Audio signals from the common party line appear on pin 3 of the XLR connector, pass through isolation transformer T

26、1801, and on to one input of diffamp U1803B. As far as signals coming into the interface are concerned, the non-inverting input of U1803B is all that matters. This audio passes on to analog switches U1801B (ignore), and U1801C (listen when called). The output of the analog switches drives U1803A, co

27、nnected as an active variable gain amplifier. The stage gain is variable from off to unity to 16dB. U1803A then feeds a mono input into the headphone amplifier. The input to the non-inverting side of the diffamp, U1803B, is also common to the output of the bi-directional current source used to drive

28、 the line. Since the current source has a high output impedance, it presents a minimal load to signals coming from the line. Another input to the diffamps inverting input comes from the current source op-amp, but prior to the current sensing resistor, R1807. The two signals are subtracted from each

29、other in the diffamp, and this partially cancels the audio signal (sidetone) that would otherwise appear at U1803B during transmit times. Without sidetone cancellation, the talkers own voice would be very loud in their own headset. CALL SIGNAL When the outside world calls the SR408s intercom station

30、, the DC call signal travels through T1801s primary, turning on darlington pair Q1802 and Q1803, which turns on opto-isolator U18. The intercom line powers this circuitry. The lowpass filter formed by R1821 and C1807 and the filtering action of C1806 prevents the call system from being activated by

31、audio signals on the line. Opto-isolator U18 isolates the intercom system ground from the SR408s ground system for call signals. On the revision 6 output PCB, the output of U18 drives the call lamp (physically located in the INTERCOM switch) via Q1805 and simultaneously turning off the LED located i

32、n the talkback switch, SW1 via Q1806. U18 also drives the listen-when-called switch U1801C. From revision A on, Q1806 was replaced by a comparator, U1804D. U1804C drives the lamp kill feature via JP1804. When the SR408 originates a call signal, current source Q1801 supplies about 3 milliamps to the

33、intercom line whenever CALL switch, SW1801 is pressed. 20 IGNORE SWITCH (Rev 6 PCB) If the SR408 shares the intercom line with the lighting company, there is a high degree of activity on the line, which would ordinarily be distracting to the mix engineer. The ignore switch isolates the SR408 from th

34、e intercom line, while still allowing it to be accessible. When the IGNORE switch, SW1802, has been depressed, analog switch U1801B opens, disconnecting the headphone system from the intercom receive audio. When a call signal comes in, U18.4 goes low, which closes analog switch U1801C, re-connecting

35、 the receive audio from the intercom to the headphone system in the SR408. During the time that the call lamp is lit, the console operator is connected to the intercom system again (assuming that theyre wearing the headphones). Answering the call by pressing the INTERCOM switch charges C144 via D180

36、6, closing analog switch U1801.8, temporarily defeating the effect of pressing the IGNORE switch for a time determined by the discharge of C144 through R1899. Double-clicking the ignore switch quickly discharges C144 through R1832, resetting the ignore state. The ignore LED monitors the state of the

37、 ignore timer (C144 and R1899) via analog switch U1801.16 and Q1807. IGNORE SWITCH (Rev A and higher PCBs) If the SR408 shares the intercom line with the lighting company, there is a high degree of activity on the line, which would ordinarily be distracting to the mix engineer. The ignore switch iso

38、lates the SR408 from the intercom line, while still allowing it to be accessible. When the IGNORE switch, SW1802, has been depressed, analog switch U1801B opens, disconnecting the headphone system from the intercom receive audio. When a call signal comes in, U18.4 goes low, which closes analog switc

39、h U1801C, re-connecting the receive audio from the intercom to the headphone system in the SR408. During the time that the call lamp is lit, the console operator is connected to the intercom system again (assuming that theyre wearing the headphones). Answering the call by pressing the INTERCOM switc

40、h charges C144 via D1806, closing analog switch U1801.8, temporarily defeating the effect of pressing the IGNORE switch for a time determined by the discharge of C144 through R1899. Double-clicking the ignore switch quickly discharges C144 through R1832, resetting the ignore state. Another comparato

41、r section monitors the state of the ignore timer (C144 and R1899) and drives the ignore LED D1803. 21 CLEAR COM JUMPER OPTIONS NameDescriptionProcedureDefault Setting Intercom pre- fader Makes talk level independent of R1741. JP1704, cut trace between pins 2 and 3, jumper pins 1 and 2. Post fader. M

42、odify talk levelUse with pre- fader mod JP1803, cut jumper between pins 2 and 3, install resistor voltage divider across pins 1, 2, and 3. Keep total value below 10k bypassed Change sidetone level (rev A and later) Use to raise or lower sidetone level using a resistor, bridge E1804/E1805 to lower, b

43、ridge E1805/E1806 to raise it. Try 4k7 for starters. See schematic. Not present. Normal sidetone cancellation is about 10 dB. More cancellation than this is highly dependent on the intercom line and its loading conditions. Listen when called Bypasses ignore switch when call signal detected locate JP

44、1801, cut trace between pins 2 and 3, jumper pins 1 and 2. Enabled. (call signal bypasses ignore switch). Talk when calledEnables microphone when call signal detected Locate JP1802, install jumper. Disabled. Could cause trouble in high-noise environments. Lamp Kill (rev A and later) Flashes console

45、lamps when call signal detected Locate JP1804, install jumper. Disabled. 22 ULTRA MUTE CIRCUIT DESCRIPTION ULTRA MUTE is a microprocessor based system that stores and recalls specific mute states on the SR408 console. The system uses a 12MHz 80C51 processor. The 80C51 CPU produces a 14 bit address.

46、The lower 8 bits are latched by a 74HC573 from the multiplexed address/data bus. User presets are stored in a 24C65 non-volatile RAM. To communicate with the console, the 80C51 CPU uses serial data sent along chains of shift registers. There are three chains of shift registers; LED, FET, and SWITCH.

47、 The serial-in- parallel-out LED chain controls all mute LEDs, the Ultra Mute control panel LEDs, and numeric display. The FET chain is also SIPO and controls the DG213 analog switch ICs, which perform the actual signal path muting. The SWITCH chain is parallel-in-serial-out. It scans all mute switc

48、hes and Ultramute control switches. All serial data is sent along the MUTE BUS. MUTE BUS PINOUT AND FUNCTION Pin #NameFunction 1LED DATASerial data for all mute LEDs, control LEDs and numeric display 2LOAD LED Updates LED data to shift register parallel outputs 3SW DATASerial data from all mute and control switches 4LOAD SWUpdates sw itch data from shift register parallel inputs 5FET DATASerial data for all FET anal