StageAccompany-SA1600-pwr-sm 维修电路原理图.pdf

CONTENTS:This manual contains confidential information. Any form ofduplication is prohibited !12345789101112 80RadioFans.CN 收音机爱 好者资料库SA 1600/800SERVICE MANUAL-Warninglnside the SA 1600/800, AC voltages up to 240 V may be present!-Connection to the mains voltageThe SA 1600/800 chassis is connected to ground by the groundingconductor in the power oord. To avoid electrical shock, plug thepower oord into a properly wired receptacle. When this groundconnection is not present or interrupted, all accessible parts ofthe amplifier can cause an electrical shock.-FusesTo avoid fire hazard, only replace fusesvalue.-ServicingDo not perform internal service or adjustments unless there isanother person present, capable of rendering first aid andreanimation.Try to perform all service work with mains power off. Remove mainsplug to be sure that there are no internal voltages present.1.2 WARRANTYSUMMARYStage Accompany warrants to the original commercial purceach new Stage Accompany product, from the date of purchoriginal purchaser until the end of the warranty period,product is free of defects in materials or workmanship.WARRANTY PERIODThe warranty period on all Stage Accompany products is five yearsfrom the date of the first consumer purchase, with the exception of:all electrical products: three years trom the date ot thetirst consumer purchase;cone assemblies in the loudspeaker and diaphragms in theCompact Drivers: one year trom the date of the first consumerpurchase;-page: 2date: 20-08-1990issue: 1by the same type andpurchaser ofpurchase by theriod, that thet.RadioFans.CN 收音机爱 好者资料库SA 1600/800SERVI CE MANUALmovable parts, such as castors, locks, handles, hinges, fans,etc: one year trom the date of the first consumer purchase;computers and associated peripherals: six months trom thedate of the first consumer purchase.-HOW TO VALIDATE THE WARRANTYTo validate warranty. customers should fill out the enclosedwarranty card and return it to Stage Accompany within ten days ofthe purchase date.The purchaser must always keep the original billof sale toestablish the date of purchase.ITEMS EXCLUDED FROM WARRANTYAppeal on warranty will be voided in case:- of defects caused by influence from the outside, accident,misuse, neglect or influence of water;- the serial number on the warranty and/or product has beendefaced, altered or removed;- of damage due to shipment;- of damage resulting from neglection of instructions listed inthe user manual;- of damage caused by incorrect, abnormal or abuse duringdelivery;- the unit has been repaired (or shown signs of repair) bysomeone not authorised by Stage Accompany;- if the warranty registration card has not been returned toStage Accompany within 10 days of purchase;- the original billof sale can not be presented wheneverwarranty service is required;- the cause of damage is unknownWHAT WE WILL DOShipment of the product to a Stage Accompany dealer is at the riskand responsibility of the customer.Stage Accompany will pay all labour and material expenses for allrepairs covered by this warranty. Stage Accompany will not pay theoost of shipment to the Stage Accompany dealer or to the factory.However Stage Accompany will pay the return shipping charges ifrepairs are covered by the warranty.320-08-19901page:date:issue:SA 1600/800SERVICE MANUALCAUTIONWarranty work can only becenters or at our factory.authorised party will voidStage Accompany reserves the right to alter specifications withoutprior notice.page:date:issue:420-08-19901performed at our authorised serviceEvery repair or attempted repair by a nonthe warranty.SA 1600/800SERV I CE MANUAL2 DESCRIPTION OF THE SA 1600/800The SA 1600/800 is a high power, high efficiency power amplifier.It features:-high powerPeak power output varies from 2 x 440 W / 8 0 to 2 x 1100 W / 2 Q.Continuous output power up to 2 x 640 W / 2 Q.The SA 800 features a peak output power from 2 x 220 W / 8 Q to 2x 550 W / 2 Q and continuous power up to 2 x 300 W / 2 Q.-high efficiencyHeat dissipation is reduced by aconventional designs.-small size, medium weightVery compact design, only 2 units high. The efficient design hasreduced the weight to 17 kg (SA 800: 15 kg)!-balanced inputThe input is electronicallyrejection.-speakon output connectorsEach channel is equiped with two high cuSpeakon output-easy use of the bridge mode facilityBridge mode switch and separate bridge mode output makes rewiringunnecessary.-reduced inrush currentMains inrush current is less than 5 Ampere!on when multiple units are used.page:date:issue:520-08-19901Watts (SA 1600) compared to1000tor excellent hum and noisebalancedent 4 pole NeutrikNo need for delay turnSA 1600/800SERVICE MANUAL3 TAKING THE SA 1600/800 APARTThe SA 1600 and the SA 800 can be taken apart in the following war:Access to the electronics can be obtained by removing the top panel.Remove the eight screws at the top and the two screws on the leftand right side of the amplifier. See figure 1.Fig 1 Removing the top panel.Then, lift of the top panel.To obtain access to the front panel, remove the bar on top of thefront by removing a screw on the left and right side of theamplifier (see fig. 2).Af ter removing the connectors to the front board and the mainsswitch, the front panel can be taken out.The back panel can be taken out in a simil.However, tor most servicing work, this panetor mostHowever,removed.page: 6date: 20-08-1990issue: 11 a similar way.this panel does not need to bewar.SA 1600/800SERVICE MANUALFig. 2 Removing the front panelNext rou will find two schematicof the amplifier and the war thepage: 7date: 20-08-1990issue: 1diagrams that explain the operationseveral boards are connected.:JZ CLZ1-:JIIz:z!, .()IloI-Z fi-ZI-0zzHSA 1600/800SERVI CE MANUAL5 BASIC OPERATION OF THE ELECTRONICSThis chapter describes some of the key circuits of the SA 1600/800.The complete circuit drawings can be found on page 15 to 26.5.1 INPUT AND PROTECTION CIRCUITRYSee page 16 tor the schematics.The front board contains the electronics tor the input amplifier andthe protection circuitry.The input amplifier is a straightforward opamp differentialamplifier.Low frequency common mode rejection can be trimmed with TR2 and TR4,high frequency CMR with TRl and TR5. These are the only adjustmentsto be made in the complete amplifier. See page 27 tor the exactadjustment procedure. The input impedance is 20 ka tor both inputlegs.Af ter the debalancing stage, the input signal can be attenuated byconductive plastic potentiometers. The signal is also fed to anetwork which detects the presence of input signal. A led willlightif the input signal exceeds -34 dBu, regardless the setting of theattenuators.For protection purposes, each input channel can be muted by relays(RLl and RL2).The protection circuitry contains:-The thermal protection senses the temperature of each poweramplifier as weIl as the transformer temperature. IC4-d calculatesthe appropriate fan speed. IC5-a/b compares the temperatures to theJ ,:_:- - -: , , ,.,programmed limits and activates the input mute relays if necessary.The power amplifier temperature limit is 85 .C. the transformerlimit is 95 .C. Af ter a thermal overload. the temperature must drop- t 5 .C before the input signal is unmuted again.A power amplifier thermal overload only mutes the related channel. Atransformer thermal overload mutes both channels.The DC protection sens es the amplifier output for DC and very lowpage: 10date: 20-08-1990issue: 1Thermal protectionFan speed controlDC protectionInrush current protectionSA 1600/800SERVI CE MANUALfrequency contents. The output relay is muted when more then 3 voltsDG (positive or negative) is detected. The circuit also providesdelayed turn on of the output relays.IC10-c controls the mains inrush current limiter. One second atterpower turn on, the transtormer series resistance is bypassed bymeans ot a relay activated by IC10-c.5.2 POWER SUPPLY CIRCUITSee page 19 tor schematics.The power supply board contains all the electronics tor rectityingand filtering 6 different supply voltages. ! 95 and ! 45 V voltagesfeed the power amplifiers (! 72 and ! 35 V for the SA 800) and ! 20V supplies feed the relays and regulators tor the ! 15 V supplies.Inrush current reduction is obtained by R4 and RLI. When the powerswitch is turned on, RLI is not active and R4 is in series with themains transformer. Therefore, maximum inrush current cannot exceed220/47 - 4.7 A. Af ter! 1 second, RL! is activated and thetransformer is connected normally to the mains. TBI protects R4 incase of failure of RLI.The SA 1600/800 can internally be set tor either 100-120 V or 220-240 V operation. The voltage range is determined by CN3 or CN4 onthe supply board and CN12 or CN13 on the mains switch board. Thecorrect jumper settings are:Note that the :!: 20 V voltages are fused by so called multifuses(F1 and F2). These devices normally have a very low impedance. Incase a current overload occurs (e.g. because of a faulty component),the internal impedance rises to a high value, simulating a blownfuse.When this happens, turn the amplifier off and perform the neededrepair. The multifuses reset automatically and do not have to bereplaced.page: 11date: 20-08-1990issue: 1SA 1600/800SERVICE MANUAL.5.3 THE POWER AMPLIFIER BOARDThe power amplifier board contains a preamplifier (driver) and theactual power amplifier. The basic electronics of the poweramp driverare shown in figure 3.T21 farms a current source together with RSO and ZS. The collectorcurrent is ! 10 mA. This source provides drain current for the dualFET T19.The input of the amplifier is connected to the gate of the leftFET, the feedback network to the gate of the right one. In a steadystate situation both input and feedback voltages are equal so baththe gate-drain voltages are the same. IIPJTFig 3.The current of T21 will be equally divided over the two fets, so 11- 12 - 5 mA.11 passes a current mirror composed of R33, 017 and T13.12 passes two current mirrors, one composed of 017, R34, and T12and the other of T14 and T15.In a steady situation 11 - 12 so all current pushed out of T13 ispulled into T15 and bath the drive currents will be zero.1220-08-19901page:date:issue:driver circuitSA 1600/800SERVIWith a rising input voltage, 11 becomes larger than 12, and not allthe current produced by T13 will be pulled into T15. The residualcurrent will be pushed into the power amplifier as drive current(source).With a negative input voltage. 12 is larger than 11 and drivecurrent will be pulled out of the power amplifier (sink).DC stability is achieved by the circuit around IC3 (see page 21). Todetect DC offset, the power amplifiers output signal is integratedand fed into the feedback loop.Fig. 4 shows theFig 4 power amplifier setupThe driver circuit provides two signaIs, drive + and drive -. Thepositive drive current is boosted by T4 and Tl and fed to the NPNpower transistors T24.T26. The negative drive current is boosted byTS and T3 and fed to T30.T32.T6 is set as a constant voltage source and provides the biascurrent for the amplifier.page: 13date: 20-08-1990issue: 1MANUALCEbasicSA 1600/800SERVI CE MANUALThe amplifier normally works on the ! 45 V power supplies throughdiodes 013, 021, 024, 016 etc.Current limiting is handled by T7 and T8. When the current drawnfrom the amplifier rises, the voltage across R26 and R27 rises too.At the moment this voltage reaches ! 0.65 V, T3 and T4 startconducting and limit the drive current for the power stage. Currentlimiting depends on the output voltage. At 0 V output the.maximumcurrent per transistor is ! 5 A rising to t 12 A at 50 V.The circuit around T22 is a current source that provides biascurrent for Z6. So Z6 is a constant voltage source of 6.2 volts.T23, T36 and T27.T29 form a high current gain amplifier. With T27to T29 having a constant emitter voltage of 45 V, this currentamplifier is biased through T22 when the output voltage is 42 V ormore and the collector voltage of T24. .T26 will rise liniair withthe output voltage. So under 42 V output, the T24. .T26 collectorvoltage is 45 V. Above 42 V, the collector voltage will be Vout + 3Volts. Thus the maximum CE voltage of any conducting powertransistor does not exceed 45 V, reducing dissipation significantly.Operation for negative output voltages is identical.Basic functioning of the SA 800 power amplifier is identical.However, voltages and currents are smaller so the SA 800 poweramplifier has 4 pairs of output transistors instead of 6.The complete schematics can be found on1600 and page 21 and 24 tor the SA 800.page: 14date: 20-08-1990issue: 121 and 22 tor the SAti)C2l:I:l(-1p.SA 1600/800 page: 27SERVICE MANUAL date: 20-08-1990issue: 17 ADJUSTMENTSAf ter repair, all adjustable signals should be checked and re-adjusted if necessary.Channel 1 low frequency common mode rejectioninput voltage: 0 dBu, 400 Hz sine, attenuator at 0 dBoutput load: 8 aadjustment location: TR4 on the front boardinstrument: AC volt metermeasure location + : Channel 1 output connector pin 1+measure location - : Channel 1 output connector pin 1-value: minimum, typical 7 mV Channel 1 high frequency common mode rejectioninput voltage: 0 dBu, 20 kHz sine, attenuator at 0 dBoutput load: 8 Qinput voltage: 0 dBu, 20 kHz sine, attenuator at 0 dBoutput load: 8 Cladjustment location: TR3 on the front boardinstrument: AC volt metermeasure location + : Channel 1 output connector pin 1+measure location - : Channel 1 output connector pin 1-value: minimum, typical 16 mV*3 Channel 2 low freQuency common mode rejectioninput voltage: 0 dBu, 400 Hz sine, attenuator at 0 dBoutput load: 8 aadjustment location: TR2 on the front boardinstrument: AC volt metermeasure location + : Channel 2 output connector pin 1+measure location - : Channel 2 output connector pin 1-value: minimum, typical 7 mVChannel 2 high frequency common mode rejectioninput voltage: 0 dBu, 20 kHz sine, attenuator at 0 dBoutput load: 8 Cadjustment location: TRI on the front boardinstrument: AC volt metermeasure location + : Channel 2 output connector pin 1+measure location - : Channel 2 output connector pin 1-value: minimum, typical 70 kHzFig 6 Typical frequency responseNext check harmonic distortion. Final test specs are:Uout - 40 Y (SA 800: 30Y) into 8 QTHD + N 10 Hz - 20 kHz 0.08 %Uout - 40 Y (SA 800: 30Y) into 4 QTHD + N 10 Hz - 20 kHz 0.2 %2920-08-19901page:date:issue:-3 dBSA 1600/800SERVI CE MANUALTypical distortion graphs are shown in fig. 7. An 80 kHz low passfilter is applied to eliminate unwanted HF products.Fig 7The tatal naise level of the SA 1600/800 si. ,.Ine tOtal nOlse level OT tne A IbUU/UU snou!c De !ess than llU dunder 50 V output level (1 kHz). For this test, a 600 C resistorshould be placed between pin 2 and pin 3 of the XLR inputconnector. The best war to test output noise is to measure frequencyresponse without an input signal. A typical graph is shown in fig.8.Next test the common mode rejection. A typicalshown in fig. 12. The norms are:CMRR:page:date:issue:3020-08-19901