Arcam-A75-int-sm维修电路原理图.pdf

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1、A65/75DiVA A65, A75 & P75 PlusAmplifi ers Service Manual ARCAMARCAMIssue 1.0RadioFans.CN 收音机爱 好者资料库 Contents List ! Contents list ! Circuit description ! Service guide ! Circuit diagrams ! Component overlays ! Circuit board parts list ! General assembly parts list RadioFans.CN 收音机爱 好者资料库A65/75/75P P

2、lus Circuit Description PSU In order get the output devices to turn fully on and achieve the greatest efficiency, an auxiliary rail is formed from a charge pump driven by the main AC outputs from the transformer. C304,305 & D301,302 charge on alternate cycles. In the other cycle the charge on C304,3

3、05 is pumped into C310,311 respectively. This creates a voltage much greater than the standard rails, but with low regulation and high ripple. This is then regulated to 38V via emitter followers Q300,302,303,305 from a zener stabilized voltage (D304,305) The Pre-amp 15V supply comes from linear regu

4、lators Z300,301. The transformer is a dual voltage unit, the required voltage being selected by which fuse holder is fitted with the appropriate fuse. If an alternative to 115V or 230V is required then a different transformer is fitted. The secondary is centre tapped for the main rails, but a separa

5、te winding is added for the uC supply. The star ground point SP300 is not a component on the PCB and is on the schematic only for layout purposes. Pre-amp The direct signal path (line in, tone controls defeated) consists of a single op-amp gain stage, buffering the j-fet input multiplexers and Tape

6、Monitor and AV switches. The selected input is AC coupled to the op-amp, the output is DC to the Pre-out, via a j-fet pre-mute switch. This switch is controlled by the uC in such a way that when ever the output relay changes state signal is removed from the power amplifier (A65/75). The MM phono sta

7、ge (by passable A75 only, SW100) is opamp based. The circuit is AC coupled to give RIAA/IEC low frequency response. The cartridge is loaded by R100,101,C119,120. The 1kHz gain is 56dB, and RIAA eq set by R110,112,111,113,C127,129,128,130. Each line input has static protection afforded by the back to

8、 back diodes (e.g. D101,103), and RF filtering is set by R118,C134 etc. The selected input is buffered for Tape output by Z104 set as a follower. The output resistor is inside the feedback loop so to keep the output impedance low and short protection is catered for. C121,122 maintain stability into

9、capacitive loads. From the tape monitor switch (Z105) onwards the signal is AC coupled (C151,152). From there the signal is fed to the tone controls. These consist of two stages: Balance and buffer (Z160), and Bass/Treble Z161. The output of this stage is again AC coupled. Switch SW162 selects wheth

10、er the tone adjusted signal or a direct signal reaches the gain section. In the A75 Z164 can be used to bypass the volume control when AV input is selected. This fixes the gain to allow an external AV processor to control the volume setting. The gain stage (Z163) has a gain of 2.2, and the same low

11、impedance output arrangement as the Tape output. The signal from this stage to the Pre- amp outputs and the Power amp input is controlled by a pre-mute (Z171). This removes thumps and clicks, and in the case of the Power amp relay changing state, removes signal so arcing will not take place. Power A

12、mplifier The new topology is a high gain voltage feedback design, with a bipolar output stage. Its signal path is designed to be fully symmetrical, despite not having a symmetrical circuit (symmetrical rail to rail). This is achieved with a new dual differential input gain block, where the input dif

13、ferential sees a symmetrical active load (Q600,601,700,701) before driving the second voltage amplification stage (VAS) differential (Q603,604,703,704). This could be described as two Wilson mirrors with their bases clamped together. The second differential also has an active load of a more traditio

14、nal mirror (Q610,611,710,711), and this gives a push pull signal to the input of the output stage, improving on the traditional single ended current source of the often called blameless topology. The input pair (Q606,607,618,619,706,707,718,719) are in a Darlington configuration to lower input curre

15、nt offset which in turn will lower DC offset at the output, as the impedances seen on the input nodes are necessarily high for the wide bandwidth required. The output stage is a simple bipolar darlington (Q614,615,714,715). However, the devices used are Darlington devices with integral diodes. This

16、means the bias temperature compensation is part of the output device enabling smaller number of devices, no extra devices on the heatsink (vital for this mechanical layout) and more consistent temperature compensation of bias. Also the resistors are also integral, saving a large amount of PCB real e

17、state and hand insertion cost, while also able to be used as bias set test points and protection sensing.Due to the decreased efficiency of this type of output stage over the previous bootstrapped Mosfet output, a separate set of rails is required for the VAS stage in order to saturate the output tr

18、ansistors. The operation of this is outlined in the Power supply section. However, these rails are individually regulated for each channel to decrease power supply crosstalk. The protection of the output stage is taken care of by a proprietary IC (Z101). This takes care of the switch on delay (R150,

19、C149), DC offset (R102,103,C147), Thermal trip (TH100), and safe operating area. The safe operating area is monitored by a network which compensates for the voltage across the output devices, current through them, and duration of power (R627,606,625,605,C617 & symmetrical associated components) and

20、this is sent to the protection IC via (Q605,612,613,616,617,712,713,716,717). The output of the protection IC is sent to the micro controller (uC) to signal the output relay (RLY1) status. Also, for output muting purposes, the uC can switch the relay via Q100. Input Selection The uC controls the ope

21、ration of the unit. IR commands are received from RX900 on a break-off PCB found on the front panel and fed via LK900/LK903 3-way ribbon. On power on/off the current state of the pre-amp switching stored in an EEPROM Z906. The input switching is 5V logic level and is direct from the uC to the DPDT a

22、nalogue switches in the case of Tape Monitor (Z105), AV (Z164,A75 only), Pre-mute (Z171) and Mute Q100. The source selector is achieved by 8 way analogue multiplexors (Z102,103) and the control signals are decoded from the uC from MUX1,2,3 by Z907 which also drives the appropriate front panel LED. T

23、he input selection is set by the remote control or the rotary encoder on the front panel display PCB. Tape monitor and AV mode(A75 only) is set by SW900. Volume Control The volume control is a motorized manual type, where the signals are routed through the 8-way ribbon LK189. The motor drive comes f

24、rom Z905, which is a logic level controllable motor driver. It has its own unregulated PSU (D907,C920),and the speed of the volume knob is dictated by the REF pin. The circuit (Q900,R905,901,C901) allows the speed to vary from just above stall to full as the volume control button is depressed on the

25、 remote. SIM Module The connector PL161 (P75 only) allows the fitting of the ARCAM SIM module. In order to allow this to operate LK172 & LK173 must be removed. This will allow 12V trigger signals to operate the P75. Headphones The Speaker outputs (SK600,700) are connected to the headphone socket (SK

26、162) via an 8-way ribbon LK170,171. The output is attenuated by a resistor network R161,162,236,237. The Relay drive is fed through the headphone sockets switch (HPSW1,2) so that when headphones are inserted the speakers are disconnected. Switch SW163 allows the separate switching of the second spea

27、ker terminals on SK600,700. A65, A75 & P75 Service Guide Fault diagnostics Fault Action No power Check mains fuse Check transformer connections Check power supply rails Stuck in protection Check power supply rails Check protection circuit voltages Check for dry joints on o/p devices Intermittent aud

28、io on one channel Check for dry joints around o/p devices Fails to respond to commands Check supply to remote circuit Check IC Z900 Check remote flex foil cable Check for dry joints on selector pcb Volume control rubs on front panel Pull knob out from fascia Audio crackles on o/p Check for component

29、 break down using hot air gun & freezer spray Check transformer connections Power supply test points Position Voltage LK125 +37 volts DC LK126 -37 volts DC LK271 or black speaker terminal 0 volts LK303 +15 volts DC LK301 - 15 volts DC Q300 emitter +38 volts DC Q304 emitter +38 volts DC Q302 emitter

30、-38 volts DC Q305 emitter -38 volts DC D910 emitter +5 volts DC remote supply IQ settings Model IQ setting Comments - (22/01/02) A65 37mV A75 37mV P75 37mV A85 12mV Set for 8.5mV cold, reset for 12mV when warm P85 12mV Set for 8.5mV cold, reset for 12mV when warm A65 plus 12 to 15mV A75 plus 12 to 1

31、5mV P75 plus 12 to 15mV Hints & tips ! To isolate a fault between pre and power stage remove C602 (left channel) or C702 (right channel). ! Always check and re-solder o/p device SAP15N and SAP15P pin connections. ! Replace Z900 IC if software version is below version 3 ( note version 82 is also ok )

32、. ! Make sure R127 is not touching LK130. ! When replacing the top cover with a new top it may be necessary to re-drill the fixing holes. ISSUEDRAWING NO.DRAWING TITLEDATEFilename:ECO No.DESCRIPTION OF CHANGEL942C1_1.0.PRJA65 PLUS AMPContact Engineer:L942C111-Dec-2001INITIALSPrinted:17SheetofNotes:C

33、ontact Tel:(01223) 203 200Travis PierceA & R Cambridge Ltd.Pembroke AvenueCambridge CB5 9PBWaterbeachPWRLEFTPROTECTIONA1SP2_SEND_LSP2_RETN_LOP_LA1LEFT CHANNELL942C5_1.0.SCHACLT1MUTEAVCONTROLTAPECONTROLMUX1MUX2MUX3PREMUTEPROT SENSEREMOTE CONTROLL942C7_1.0.SCHSELOPRSELOPLMUX1MUX2MUX3TAPECONTROLACSENSE

34、PROT_OP_LPROT_OP_RPROTECTIONMUTEHPSW2HPSW1TAPOLTAPORPROT SENSEPHONO & INPUTSL942C3_1.0.SCHACSENSEACLT1POWER SUPPLYL942C2_1.0.SCHPWRRIGHTA1SP2_RETN_ROP_RSP2_SEND_RA1RIGHT CHANNELL942C6_1.0.SCHPWRLEFTPWRRIGHTSELOPRSELOPLHPSW2AVCONTROLHPSW1SP2_SEND_LSP2_RETN_LOP_LOP_RSP2_SEND_RSP2_RETN_RPREMUTETAPORTAP

35、OLPROT_OP_RPROT_OP_LTONE CONTROLL942C4_1.0.SCHTGP12/12/01PRODUCTION RELEASE1.0USE exlude A65 FILTER FOR BOM01_E020TOP SHEET FOR A65 L942AYISSUEDRAWING NO.DRAWING TITLEDATEFilename:ECO No.DESCRIPTION OF CHANGEL942C5_1.0.SCHA65 PLUS AMPContact Engineer:L942C511-Dec-2001INITIALSPrinted:57SheetofNotes:C

36、ontact Tel:(01223) 203 200Travis PierceA & R Cambridge Ltd.Pembroke AvenueCambridge CB5 9PBWaterbeachQ600BC556BQ601BC556BQ6042SA970GRQ606BC546BQ607BC546BR617680R MFR61910K MFR61810K MFR61347R MFR61447R MFR612100K MFR6001K0 MFPWRLEFTQ6112SC2240GRQ6102SC2240GRR62010K MFQ6032SA970GRQ608BC546BQ609BC546B

37、+C601100U EL 100V+C600100U EL 100V0V_HF+C61610U ELL6002U2H LAC SMALLR6312R2 CFR6304R7 W2 CFD6031N4003F+37V-37VC621470P CDRLY1ARLY G5Z-2A-EC620470P CDC6221N0 CDSPLD600SPLS600PD6OP_LSP2_SEND_LSP2_RETN_LR6162K7 MFR611100K MFC603100P PPW0V_SIG0V_HF0V_SIG0V_HFQ6122SC2240GRR627430R MFR606100R MFR605100R M

38、FR6256K8 MFR62210K MFR621680R MFR62947K MF+C61710U ELQ605BC556BA1PROTECTIOND6041N4003FR628430R MFR6266K8 MF+C61810U ELR608100R MFR607100R MFA1D6051N4148D6061N41480V_LS_L0V_LS_LQ602BC556BR61547R MFR601100R MFR602100R MFR603100R MFR604100R MFSPLE600Left Channel Power AmplifierQ614SAP15NQ615SAP15PD6004

39、V7 400MW0V_HF0V_HF0V_HF0V_HFQ6162SA970GRD601ZENER 400MW 27VD602ZENER 400MW 27VR610100R MFR609100R MFR62310K MFQ613BC546BR62410K MFC608100P PPWC607 100P PPWQ619BC546BQ618BC546BR63312K MFR63212K MF+C60222U SILMIC 2+C605100U SILMIC 2+38V_L-38V_LC604100P PPW0V_LS_LBias-L +Bias-L -21mm x 32mmSELF ADHESIV

40、EE852MCQ2 PADSP600Q2-PAD-SAP21mm x 32mmSELF ADHESIVEE852MCQ2 PADSP601Q2-PAD-SAPC60922N CDCL600E856MCCL601E856MCTGP12/12/01PRODUCTION RELEASE1.0Q617ZTX653+C624100U 25V ZA ELR634470K MF+C62510U ELSET BIAS TO 12mV01_E020C623100N PE 100VC610100N PE 100VC613100N PE 100VC611100N PE 100VC612100N PE 100VC61

41、4100N PE 100VC615100N PE 100VC619100N PE 100VRV600220R PSET+C603100U 50V YXF LOW Z+C626100U 50V YXF LOW Z Top+ Top-SK600ASPKSKT_G Bot+ Bot-SK600BSPKSKT_G CHASSSK600CSPKSKT_GHS600E81801-75HS601E81801-75HS602E81801-75HS603E81801-75USE exlude A65 FILTER FOR BOMISSUEDRAWING NO.DRAWING TITLEDATEFilename:

42、ECO No.DESCRIPTION OF CHANGEL942C7_1.0.SCHA65 PLUS AMPContact Engineer:L942C711-Dec-2001INITIALSPrinted:77SheetofNotes:Contact Tel:(01223) 203 200Travis PierceA & R Cambridge Ltd.Pembroke AvenueCambridge CB5 9PBWaterbeachWARNING SAFETY CRITICAL COMPONENTREPLACE WITH IDENTICAL PARTuC, Volume Drive &

43、Remote ControlC91210N CDC90010N CDR9001R0 FUD9061N4003FD9071N4003F+C9201M0 25VC91310N CDMOTE900P900+5vVOLUME DRIVEMOTOR DRIVER+5VGND1MD12CC13REF4MC15MC26VCC17VCC28CC29MD210Z905BA610912VOLMOT9001Y271ACLT1MUTEMUX1MUX2MUX3AVCONTROLTAPECONTROLR915220R MFA01A12A23VSS4SDA5SCL6WP7VDD8Z90624C01C917100N CDX9

44、00CST4.00C918100N CD+C914220U EL+5v+5v+5vC919100N CD123SW900A2PCO_NON_LAT456SW900B2PCO_NON_LATR912100K MF+C92110U ELD9101N4148R91310K MF+5v+5VR9144K7 MF0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIG0V_DIGVDD16GND8Z907B74HC4051R90410R MF+C915100U ELPREMUTE0V_DIG+5VMOTSUP900V

45、OLM901VOLM900REMO900C916100N CD123LK9033WAY CABLE HOLDERD9111N414812345678910SK900FFC10VR902100R MFR903100R MF0V_DIG0V_DIGPROT SENSEDisp ADisp BDisp CDisp DDisp EDisp FDisp GDisp HDisp IR90112K MFQ900BC556B+5vR90533K MF+C901100U ELD908ZENER 5V1 400MWX013X114X215X312X41X55X62X74INH6A11B10C9VEE7X3Z907

46、A74HC4051TGP12/12/01PRODUCTION RELEASE1.001_E020132LK900L856CAREMOTE SENSOR SNAP OFF BOARD+5V3O/P2GND1CaseCaseO/PGND+5VRX900PIC-26043TM2IR RXSUPPORT PADSP1IR RX SUPPORT PADPB51PB42PA33PA24PA15PA06PB37PB28PB19PB010VSS11(TMR)/INT12PC013PC114PC215PC316PC417PC518RES19VDD20OSC121OSC222PA723PA624PA525PA42

47、6PB727PB628Z900HT48R30 28-DIP-B-0USE exlude A65 FILTER FOR BOMISSUEDRAWING NO.DRAWING TITLEDATEFilename:ECO No.DESCRIPTION OF CHANGEL942C3_1.0.SCHA65 PLUS AMPContact Engineer:L942C311-Dec-2001INITIALSPrinted:37SheetofNotes:Contact Tel:(01223) 203 200Travis PierceA & R Cambridge Ltd.Pembroke AvenueCa

48、mbridge CB5 9PBWaterbeach321Z100ANE5532C119100P PPR10047K MFR108470R MFC12447P CD+C12522U ELR110680K MFR11256K MFC1274N7 PPC1291N3 PPC120100P PPR10147K MFR109470R MFC12347P CD+C12622U ELR111680K MFR11356K MFC1284N7 PPC1301N3 PP567Z100BNE5532-15V+15VCDTUNERVCRAV/DVDTAPE INTAPE OUTEMC1NFSK100APHONO4GB

49、OT56TOP4NFSK100BPHONO4GEMC1NFSK103APHONO4GNFSK103BPHONO4GEMC1NFSK102APHONO4GNFSK102BPHONO4GEMC1NFSK101APHONO4G84Z100CNE5532Phono Stage & Input SelectionD1041N4148D1061N4148D1051N4148D1071N4148D1081N4148D1121N4148D1131N4148D1091N4148D1141N4148D1101N4148D1151N4148D1111N4148D1241N4148D1201N4148D1211N41

50、48D1251N4148D1221N4148D1261N4148D1231N4148D1271N4148D1011N4148D1031N4148D1001N4148D1021N4148R1181K0 MFR1191K0 MFR1221K0 MFR1231K0 MFR1241K0 MFR1251K0 MFR1261K0 MFR1271K0 MFR1281K0 MFR1211K0 MFR130100K MFR131100K MFR133100K MFR134100K MFR135100K MFR136100K MFR137100K MFR142100K MFR143100K MFR144100K