StageAccompany-SA800-pwr-sm维修电路原理图.pdf

CONTENTS: This manual contains confidential information. Any form of duplication is prohibited ! 1 2 3 4 5 7 8 9 10 11 12 80 RadioFans.CN 收音机爱 好者资料库 SA 1600/800 SERVICE MANUAL -Warning lnside the SA 1600/800, AC voltages up to 240 V may be present! -Connection to the mains voltage The SA 1600/800 chassis is connected to ground by the grounding conductor in the power oord. To avoid electrical shock, plug the power oord into a properly wired receptacle. When this ground connection is not present or interrupted, all accessible parts of the amplifier can cause an electrical shock. -Fuses To avoid fire hazard, only replace fuses value. -Servicing Do not perform internal service or adjustments unless there is another person present, capable of rendering first aid and reanimation. Try to perform all service work with mains power off. Remove mains plug to be sure that there are no internal voltages present. 1.2 WARRANTY SUMMARY Stage Accompany warrants to the original commercial purc each new Stage Accompany product, from the date of purch original purchaser until the end of the warranty period, product is free of defects in materials or workmanship. WARRANTY PERIOD The warranty period on all Stage Accompany products is five years from the date of the first consumer purchase, with the exception of: all electrical products: three years trom the date ot the tirst consumer purchase; cone assemblies in the loudspeaker and diaphragms in the Compact Drivers: one year trom the date of the first consumer purchase; - - page: 2 date: 20-08-1990 issue: 1 by the same type and purchaser of purchase by the riod, that the t. RadioFans.CN 收音机爱 好者资料库 SA 1600/800 SERVI CE MANUAL movable 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 the date of the first consumer purchase. - - HOW TO VALIDATE THE WARRANTY To validate warranty. customers should fill out the enclosed warranty card and return it to Stage Accompany within ten days of the purchase date. The purchaser must always keep the original billof sale to establish the date of purchase. ITEMS EXCLUDED FROM WARRANTY Appeal 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 been defaced, altered or removed; - of damage due to shipment; - of damage resulting from neglection of instructions listed in the user manual; - of damage caused by incorrect, abnormal or abuse during delivery; - the unit has been repaired (or shown signs of repair) by someone not authorised by Stage Accompany; - if the warranty registration card has not been returned to Stage Accompany within 10 days of purchase; - the original billof sale can not be presented whenever warranty service is required; - the cause of damage is unknown WHAT WE WILL DO Shipment of the product to a Stage Accompany dealer is at the risk and responsibility of the customer. Stage Accompany will pay all labour and material expenses for all repairs covered by this warranty. Stage Accompany will not pay the oost of shipment to the Stage Accompany dealer or to the factory. However Stage Accompany will pay the return shipping charges if repairs are covered by the warranty. 3 20-08-1990 1 page: date: issue: SA 1600/800 SERVICE MANUAL CAUTION Warranty work can only be centers or at our factory. authorised party will void Stage Accompany reserves the right to alter specifications without prior notice. page: date: issue: 4 20-08-1990 1 performed at our authorised service Every repair or attempted repair by a non the warranty. SA 1600/800 SERV I CE MANUAL 2 DESCRIPTION OF THE SA 1600/800 The SA 1600/800 is a high power, high efficiency power amplifier. It features: -high power Peak 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 2 x 550 W / 2 Q and continuous power up to 2 x 300 W / 2 Q. -high efficiency Heat dissipation is reduced by a conventional designs. -small size, medium weight Very compact design, only 2 units high. The efficient design has reduced the weight to 17 kg (SA 800: 15 kg)! -balanced input The input is electronically rejection. -speakon output connectors Each channel is equiped with two high cu Speakon output -easy use of the bridge mode facility Bridge mode switch and separate bridge mode output makes rewiring unnecessary. -reduced inrush current Mains inrush current is less than 5 Ampere! on when multiple units are used. page: date: issue: 5 20-08-1990 1 Watts (SA 1600) compared to1000 tor excellent hum and noisebalanced ent 4 pole Neutrik No need for delay turn SA 1600/800 SERVICE MANUAL 3 TAKING THE SA 1600/800 APART The 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 left and 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 the front by removing a screw on the left and right side of the amplifier (see fig. 2). Af ter removing the connectors to the front board and the mains switch, 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: 6 date: 20-08-1990 issue: 1 1 a similar way. this panel does not need to be war. SA 1600/800 SERVICE MANUAL Fig. 2 Removing the front panel Next rou will find two schematic of the amplifier and the war the page: 7 date: 20-08-1990 issue: 1 diagrams that explain the operation several boards are connected. :JZ CLZ 1- :JI I z :z ! , . () Ilo I-Z fi-Z I- 0 z z H SA 1600/800 SERVI CE MANUAL 5 BASIC OPERATION OF THE ELECTRONICS This 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 CIRCUITRY See page 16 tor the schematics. The front board contains the electronics tor the input amplifier and the protection circuitry. The input amplifier is a straightforward opamp differential amplifier. Low frequency common mode rejection can be trimmed with TR2 and TR4, high frequency CMR with TRl and TR5. These are the only adjustments to be made in the complete amplifier. See page 27 tor the exact adjustment procedure. The input impedance is 20 ka tor both input legs. Af ter the debalancing stage, the input signal can be attenuated by conductive plastic potentiometers. The signal is also fed to a network which detects the presence of input signal. A led willlight if the input signal exceeds -34 dBu, regardless the setting of the attenuators. 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 power amplifier as weIl as the transformer temperature. IC4-d calculates the appropriate fan speed. IC5-a/b compares the temperatures to the J ,:_:- - -: , , ,., programmed limits and activates the input mute relays if necessary. The power amplifier temperature limit is 85 .C. the transformer limit 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. A transformer thermal overload mutes both channels. The DC protection sens es the amplifier output for DC and very low page: 10 date: 20-08-1990 issue: 1 Thermal protection Fan speed control DC protection Inrush current protection SA 1600/800 SERVI CE MANUAL frequency contents. The output relay is muted when more then 3 volts DG (positive or negative) is detected. The circuit also provides delayed turn on of the output relays. IC10-c controls the mains inrush current limiter. One second atter power turn on, the transtormer series resistance is bypassed by means ot a relay activated by IC10-c. 5.2 POWER SUPPLY CIRCUIT See page 19 tor schematics. The power supply board contains all the electronics tor rectitying and filtering 6 different supply voltages. ! 95 and ! 45 V voltages feed the power amplifiers (! 72 and ! 35 V for the SA 800) and ! 20 V supplies feed the relays and regulators tor the ! 15 V supplies. Inrush current reduction is obtained by R4 and RLI. When the power switch is turned on, RLI is not active and R4 is in series with the mains transformer. Therefore, maximum inrush current cannot exceed 220/47 - 4.7 A. Af ter! 1 second, RL! is activated and the transformer is connected normally to the mains. TBI protects R4 in case 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 on the supply board and CN12 or CN13 on the mains switch board. The correct 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. In case a current overload occurs (e.g. because of a faulty component), the internal impedance rises to a high value, simulating a blown fuse. When this happens, turn the amplifier off and perform the needed repair. The multifuses reset automatically and do not have to be replaced. page: 11 date: 20-08-1990 issue: 1 SA 1600/800 SERVICE MANUAL . 5.3 THE POWER AMPLIFIER BOARD The power amplifier board contains a preamplifier (driver) and the actual power amplifier. The basic electronics of the poweramp driver are shown in figure 3. T21 farms a current source together with RSO and ZS. The collector current is ! 10 mA. This source provides drain current for the dual FET T19. The input of the amplifier is connected to the gate of the left FET, the feedback network to the gate of the right one. In a steady state situation both input and feedback voltages are equal so bath the gate-drain voltages are the same. IIPJT Fig 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 T12 and the other of T14 and T15. In a steady situation 11 - 12 so all current pushed out of T13 is pulled into T15 and bath the drive currents will be zero. 12 20-08-1990 1 page: date: issue: driver circuit SA 1600/800 SERVI With a rising input voltage, 11 becomes larger than 12, and not all the current produced by T13 will be pulled into T15. The residual current will be pushed into the power amplifier as drive current (source). With a negative input voltage. 12 is larger than 11 and drive current will be pulled out of the power amplifier (sink). DC stability is achieved by the circuit around IC3 (see page 21). To detect DC offset, the power amplifiers output signal is integrated and fed into the feedback loop. Fig. 4 shows the Fig 4 power amplifier setup The driver circuit provides two signaIs, drive + and drive -. The positive drive current is boosted by T4 and Tl and fed to the NPN power transistors T24.T26. The negative drive current is boosted by TS and T3 and fed to T30.T32. T6 is set as a constant voltage source and provides the bias current for the amplifier. page: 13 date: 20-08-1990 issue: 1 MANUALCE basic SA 1600/800 SERVI CE MANUAL The amplifier normally works on the ! 45 V power supplies through diodes 013, 021, 024, 016 etc. Current limiting is handled by T7 and T8. When the current drawn from the amplifier rises, the voltage across R26 and R27 rises too. At the moment this voltage reaches ! 0.65 V, T3 and T4 start conducting and limit the drive current for the power stage. Current limiting depends on the output voltage. At 0 V output the.maximum current per transistor is ! 5 A rising to t 12 A at 50 V. The circuit around T22 is a current source that provides bias current 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 T27 to T29 having a constant emitter voltage of 45 V, this current amplifier is biased through T22 when the output voltage is 42 V or more and the collector voltage of T24. .T26 will rise liniair with the output voltage. So under 42 V output, the T24. .T26 collector voltage is 45 V. Above 42 V, the collector voltage will be Vout + 3 Volts. Thus the maximum CE voltage of any conducting power transistor 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 power amplifier has 4 pairs of output transistors instead of 6. The complete schematics can be found on 1600 and page 21 and 24 tor the SA 800. page: 14 date: 20-08-1990 issue: 1 21 and 22 tor the SA ti) C2 l:I:l (-1 < p. SA 1600/800 page: 27 SERVICE MANUAL date: 20-08-1990 issue: 1 7 ADJUSTMENTS Af ter repair, all adjustable signals should be checked and re- adjusted if necessary. Channel 1 low frequency common mode rejection input voltage: 0 dBu, 400 Hz sine, attenuator at 0 dB output load: 8 a adjustment location: TR4 on the front board instrument: AC volt meter measure 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 rejection input voltage: 0 dBu, 20 kHz sine, attenuator at 0 dB output load: 8 Q input voltage: 0 dBu, 20 kHz sine, attenuator at 0 dB output load: 8 Cl adjustment location: TR3 on the front board instrument: AC volt meter measure 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 rejection input voltage: 0 dBu, 400 Hz sine, attenuator at 0 dB output load: 8 a adjustment location: TR2 on the front board instrument: AC volt meter measure location + : Channel 2 output connector pin 1+ measure location - : Channel 2 output connector pin 1- value: minimum, typical < 7 mV Channel 2 high frequency common mode rejection input voltage: 0 dBu, 20 kHz sine, attenuator at 0 dB output load: 8 C adjustment location: TRI on the front board instrument: AC volt meter measure location + : Channel 2 output connector pin 1+ measure location - : Channel 2 output connector pin 1- value: minimum, typical 70 kHz Fig 6 Typical frequency response Next check harmonic distortion. Final test specs are: Uout - 40 Y (SA 800: 30Y) into 8 Q THD + N 10 Hz - 20 kHz 0.08 % Uout - 40 Y (SA 800: 30Y) into 4 Q THD + N 10 Hz - 20 kHz 0.2 % 29 20-08-1990 1 page: date: issue: -3 dB SA 1600/800 SERVI CE MANUAL Typical distortion graphs are shown in fig. 7. An 80 kHz low pass filter is applied to eliminate unwanted