QSC-RMXseries-pwr-sm 维修电路原理图.pdf

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1、Technical Service ManualRMX SeriesLLLLLRMX 850LLLLLRMX 1450LLLLLRMX 2450*TD-000098-00*TD-000098-00Rev. BRadioFans.CN 收音机爱 好者资料库RadioFans.CN 收音机爱 好者资料库RMX Series Technical Service Manual1QSC Audio Products, Inc.Technical Services GroupPhone:1-800 QSC AUDIO (1-800-772-2834) USA only+1 (714) 957-7150Fa

2、x:+1 (714) 754-6173Postal:1665 MacArthur Blvd.Costa Mesa, California 92626 USAE-mail:tech_Web:http:/ (product information and support)http:/ (parts and accessory sales)RMX 850RMX 1450RMX 2450RMX SeriesTechnical Service ManualCopyright 2001, 2002 QSC Audio Products, Inc. All rights reserved.Document

3、# TD-000098-00, Rev. B. Released February 2002.2QSC Audio Products, Inc.RMX 850RMX 1450RMX 2450OUTPUT POWER in wattsFTC: 20 Hz20 kHz 0.1% THD, both channels driven8 per channel1852604504 per channel280400650EIA: 1 kHz 0.1% THD, both channels driven8 per channel2002805004 per channel3004507501 kHz 1%

4、 THD, typical, both channels driven2 per channel4307001200Bridge Mono:8, 20 Hz20 kHz, 0.1% THD53080013008, 1 kHz, 0.1% THD60090015004, 1 kHz, 1% THD, typical83014002400DYNAMIC HEADROOM2 dB 4DISTORTIONSMPTE-IM 0.01% 0.01% 300 8NOISE (unweighted 20 Hz to 20 kHz, below rated output)100 dB100 dB100 dBVO

5、LTAGE GAIN31.6 (30 dB)40 (32 dB)50 (34 dB)INPUT SENSITIVITY, V RMSfull rated power 81.15v (+3.4 dBu)1.15v (+3.4 dBu)1.23v (+4.0 dBu)INPUT IMPEDANCE10 K unbalanced20 K balancedCONTROLSFront: AC switch, Ch. 1 and Ch. 2 gainRear: 10-position DIP switchINDICATORSPOWER:Green LEDCLIP:Red LED, 1 per channe

6、lSIGNAL:Yellow LED, 1 per channelCONNECTORSInput:Active balanced; XLR and (6.3 mm) TRS, tip and pin 2 positive, and barrier stripOutput:“Touch-Proof” binding posts and Neutrik SpeakonCOOLINGContinuously variable speed fan, back-to-front air flowAMPLIFIER PROTECTIONFull short circuit, open circuit, t

7、hermal, ultrasonic, and RF protectionStable into reactive or mismatched loadsLOAD PROTECTIONTurn-on/turn-off muting, AC coupling, triac crowbar (on each channel)OUTPUT CIRCUIT TYPEABABHAB: Class AB complementary linear outputH: Class AB complementary linear output with Class H 2-step high efficiency

8、 circuitDIMENSIONS19.0 (48.3 cm) wide, 3.5 (8.9 cm) tall (2 rack spaces)15.9 (40 cm) deep (rack mounting to rear support ears)WEIGHTShipping:41 lb. (18.6 kg)46 lb. (20.9 kg)50.5 lb. (23 kg)Net:35 lb. (15.9 kg)40 lb. (18.2 kg)44.5 lb. (20.2 kg)POWER REQUIREMENTSAvailable for 120 or 220240 VAC, 50/60

9、HzPOWER CONSUMPTION 120 VAC(both channels driven)Multiply currents by 0.5 for 230V unitsUS patents pendingSPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICEl ac i pyT1l l uF2xaM3e l d IA5 . 08 A3A1 . 4A4 . 74 A5 . 4A6 . 6A5 . 112 A5 . 6*A5 . 9*A71l ac i pyT1l l uF2xaM3e l d IA5 . 08 A7 . 3A4 . 5A014 A6

10、A6 . 9A612 A3 . 9*A7 . 41*A52l ac i pyT1l l uF2xaM3e l d IA6 . 08 A4A7 . 9A4 . 614 A3 . 6A6 . 51A722 A2 . 9*A32*A14RMX Series Performance SpecificationsRMX Series Technical Service Manual3Table of ContentsRMX Series Performance Specifications . 41. Introduction . 61.1 Service bulletins. 61.2 The wel

11、l-equipped service bench . 61.3 Working with surface-mount components . 61.4 Series description . 81.5 Technical descriptions and theory of operation. 82. Component identification and pinout . 103. Troubleshooting: Symptoms, causes, & remedies . 123.1 Excessive current draw . 123.2 Protection, mutin

12、g, and turn-on/turn-off delay problems . 123.3 Faults with signal present. 133.4 Instability. 133.5 Power supply & rail balancing problems . 144. RMX calibration procedures . 144.1 Setting bias . 144.2 Setting positive and negative current limits. 155. Servicing RMX amplifiers . 165.1 Mechanical dis

13、assembly and re-assembly. 166. Replacement parts. 176.1 RMX 850 Replacement Parts. 176.2 RMX 1450 Replacement Parts. 206.3 RMX 2450 Replacement Parts. 237. Schematics and diagrams. 277.1 RMX Assembly/Disassembly Diagram 1 of 2 (All models).277.2 RMX Assembly/Disassembly Diagram 2 of 2 (All models).2

14、87.3 RMX 850 Schematic Diagram 1 of 3 Channel 1 .297.4 RMX 850 Schematic Diagram 2 of 3 Channel 2 .307.5 RMX 850 Schematic Diagram 3 of 3 Power Supply .317.6 RMX 1450 Schematic Diagram 1 of 3 Channel 1 .327.7 RMX 1450 Schematic Diagram 2 of 3 Channel 2 .337.8 RMX 1450 Schematic Diagram 3 of 3 Power

15、Supply .347.9 RMX 2450 Schematic Diagram 1 of 3 Channel 1 .357.10 RMX 2450 Schematic Diagram 2 of 3 Channel 2 .367.11 RMX 2450 Schematic Diagram 3 of 3 Power Supply .377.12 RMX 850 Chassis Wiring Diagram . 387.13 RMX 1450 Chassis Wiring Diagram . 397.14 RMX 2450 Chassis Wiring Diagram . 404QSC Audio

16、 Products, Inc.Solder braid1. Introduction1.1 Service bulletinsContact QSC Technical Services to make sure you have the most up-to-date service bulletins for RMX Series amplifiers. Service bulletinsmay be distributed in hard copy, via fax, and electronically (Adobe Acrobat PDF) via CD-ROMs, FTP from

17、 the QSC web site(), and e-mail.These service bulletins had been issued at the time this manual was printed: RMX0001, “Q205 Lead Stress” (RMX 2450 only); RMX0002,“RMX Turn-on Delay” (all RMX models); RMX0003, “RMX 2450 Turn-off Mute” (RMX 2450); RMX0004, “RMX 2450 AC Wire Routing”(RMX 2450); RMX0005

18、, “RMX 2450 AC Wire Replacement” (RMX 2450); and RMX0006, “RMX 2450 IRFZ44N Field Effect Transistors (RMX 2450).1.3 Working with surface-mount componentsRMX amplifiers, like many modern electronic products, use surface-mount technology (SMT) components where appropriate in order tomake high-density

19、circuitry that is reliable and economical to manufacture.SMT components in the RMX amps are used in the small-signal and control circuits, so they do not handle significant amounts of power;therefore, they are subject to very little stress and should seldom fail. Sometimes they do fail, or they requ

20、ire replacement for a performanceupgrade or modification. Thus, it is important to know how to work with SMT components.Specialized tools and equipment exist for soldering, unsoldering, and removing SMT components quickly andefficiently, but they are often expensive. Most SMT repairs, though, can be

21、 handled reasonably well with commontools and equipment, such as tweezers, solder braid, and fine-tip soldering irons. The original factory componentsare tacked to the board with a spot of glue, so you might have to apply some force to break the adhesive.Two-terminal components (resistors, capacitor

22、s, diodes, etc.)Removal1 Use two soldering irons, preferably about 25 to 40 watts, with fine tips.2 With a soldering iron in each hand, hold one tip on the solder at one end of the component and the othertip on the other end (Figure 1.1).3 Once the solder melts on both ends, grip the component betwe

23、en the two tips and lift it from the circuitboard.4 Use solder braid and a soldering iron to remove the solder from the two pads (Figure 1.2).1.2 The well-equipped service benchTo properly service RMX amplifiers, a technician needs the right tools. The technicians service bench should have the follo

24、wing equipment: Digital multimeter with RMS AC voltage and current Digital clamp-on ammeter Dual-trace oscilloscope Audio distortion analyzer Non-inductive load resistors, configurable as 8 ohms (min. 500 watts capacity), as 4 ohms (min. 750 watts capacity), and 2 ohms (min.1200 watts capacity) Vari

25、able AC voltage source, such as a Variac or Powerstat variable transformer, with a rated current capacity of up to 25A (for 120Vmodels) or 12A (for 230V models) Low-distortion audio sine wave generator Philips and flat screwdrivers Soldering iron with a fine tip (2560W recommended) Rosin-core solder

26、 (60/40 or 63/37) Long-nose pliers Diagonal cutters Wire strippersAutomated test equipment, such as an Audio Precision workstation, is very useful for servicing RMX amplifiers. Contact QSC TechnicalServices to obtain applicable AP test files.Figure 1.1.Figure 1.2.RMX Series Technical Service Manual5

27、SolderSolderTweezersSolderInsertion1 With a soldering iron and 60/40 or 63/37 eutectic-type solder, melt just enough solder onto one pad tocreate a small mound (Figure 1.3).2 Grasp the component in the middle with tweezers. Melt the small mound of solder with the iron andplace the component across t

28、he two pads (in the correct orientation, if the component is sensitive todirection) and press it flat against the circuit board, with one end of the component immersed in themelted solder (Figure 1.4).3 Hold the component in place and take the soldering iron away. Let the solder harden to tack theco

29、mponent in place.4 Fully solder the other end of the component to its pad. Let the solder harden (Figure 1.5).5 Fully solder the tacked end of the component to its pad (Figure 1.6).Three-terminal components (transistors, etc.)Removal1 With a soldering iron and solder braid, remove as much solder as

30、possible from the middle terminal ofthe component.2 With a soldering iron in each hand, hold one tip on the solder at the terminal at one end of the compo-nent and the other tip on the terminal at the other end.3 When the solder on both ends melts, grip the component between the two tips and lift it

31、 from the circuitboard. You might need to quickly touch the pad on the middle terminal with a soldering iron to melt anyremaining solder that might be holding the component down.4 Use solder braid and a soldering iron to remove the solder from the three pads.Insertion1 With a soldering iron and 60/4

32、0 or 63/37 eutectic-type solder, melt just enough solder onto one pad to create a small mound of solder.2 Grasp the component with tweezers. Melt the small mound of solder with the iron and place the component in the correct orientationacross the three pads and press it flat against the circuit boar

33、d, with one terminal of the component pressed into the melted solder.3 Hold the component in place and take the soldering iron away. Let the solder harden to tack the component in place.4 Fully solder the other terminals of the component to their pads. Let the solder harden.5 Fully solder the tacked

34、 terminal of the component to its pad.Multi-pin components (ICs, etc.)RemovalRemoving a multi-pin SMT component is a delicate procedure. Ideally, you should use a soldering iron with an attachment that allows you toheat all the pins simultaneously.If such a soldering device is not available, use thi

35、s procedure:1 Use a soldering iron and solder braid to remove as much solder as possible from the pins of the component.2 With fine tweezers, carefully try to lift each pin to see if its free. If its not, touch it with the tip of the soldering iron and if necessary, usethe solder braid to remove the

36、 remaining solder.3 Repeat the process until all the pins are free and you can remove the component.Insertion1 With a soldering iron and 60/40 or 63/37 eutectic-type solder, melt just enough solder onto one pad to create a small mound of solder. Itis usually easiest to use a pad that corresponds to

37、one of the end or corner pins of the component.2 Grasp the component with tweezers. Melt the small mound of solder with the iron and place the component in the correct orientationupon its pads and gently press it flat against the circuit board, with the appropriate terminal of the component pressed

38、into the meltedsolder.3 Hold the component in place and take the soldering iron away. Let the solder harden to tack the component in place.4 Fully solder the other terminals of the component to their pads. Let the solder harden.5 Fully solder the tacked terminal of the component to its pad.Figure 1.

39、3.Figure 1.4.Figure 1.5.Figure 1.6.6QSC Audio Products, Inc.1.4 Series descriptionQSCs RMX Series amplifiers are entry-level professional audioproducts, designed for good, basic performance and reliability atlow price. The series comprises three models: the RMX 850, RMX1450, and RMX 2450. Each one h

40、as two audio channels and is tworack spaces tall. See page 2 for complete specifications.The RMX 850 and RMX 1450 have single-sided printed circuitboards. The RMX 2450 uses double-sided boards.1.5 Technical descriptions andtheory of operationNote: Some of these descriptions concern circuitry that is

41、 duplicatedin the amplifiers two channels. For the sake of simplicity, thedescriptions are of Channel 1 only. Components in Channel 1 have a3-digit designation with “1” asthe first digit; their equivalents inChannel 2 have a “2” as the firstdigit, followed by the same twonumerals. For example, R122

42、andR222 have identical functions intheir respective channels.Power suppliesUnlike other recent QSC amplifiers,the RMX line uses strictly conventional power supplies, with largetransformers that operate at the 50 or 60 Hz frequency of the ACline. The electrical current in the secondary circuitry is c

43、onverted toDC through a full-wave bridge rectifier. The resulting 100 or 120 Hzripple is filtered out by large capacitors that also serve as currentreservoirs for short-term, transient demands.The supply provides a bipolar set of supply rails for each channel, withequal quiescent positive and negati

44、ve voltages, as shown in Figure 1.7.Note that unlike many bipolar supplies for complementary transistorarrangements, the secondary windings are not connected to ground atthe center. This is because the output transistors are directly mountedto the heat sink, metal-to-metal, to maximize heat transfer

45、; this groundsthe collectors, requiring somewhat different output and power supplyarrangements. The grounded-collector concept is described later inthis chapter.In the RMX 2450, thesecondaries are tapped toprovide an intermediate setof bipolar rails for the Class Houtput circuitry. Figure 1.8shows o

46、ne channel. Class Hoperation is described laterin this chapter.The 24-volt cooling fan isdriven by a separate DCsupply that is powered by a+Vcc-Vcc+Vcc-VccChannel 1Channel 2+110V-110V+55V-55VChannel 1Ch. 1 Center TapTo Channel 2 Center Tap125W20.047 F20-volt tap on the transformer primary. To minimi

47、ze fan noise, thefan speed is controlled by varying its actual DC voltage in responseto the amplifiers heat sink temperatures. An optocoupler isolatesthe fan control circuitry from the thermal sensors.Audio circuitryThe audio inputs are balanced to offer a reasonably high amount ofcommon-mode noise

48、rejection. The input balancing is done using asingle op amp (one half of an NE5532 dual op amp) arranged as adifferential amplifier. The degree of common-mode rejection isdependent on a close match between the input resistors (R100 andR101 in Figure 1.9) and between the feedback resistor and the shu

49、ntresistor (R105 and R106). The circuitry uses 1% precision resistorsto ensure at least 40 dB of common-mode rejection.The feedback and shunt capacitors, C101 and C103, add a first-orderhigh-frequency roll-off, down 3 dB at 88.4 kHz (over two octavesabove the high end of the audio spectrum). This ma

50、kes the amplifierless susceptible to RF interference, high-frequency oscillations, etc.Also in this stage, the feedback loop contains one half of a 13600 dualoperational transconductance amplifier (Figure 1.10). The OTA is partof the clip limiter circuitry; when the clip limiter is activated, a cont