Studer Revox B740 Page 39 Service Instructions Manual Download | Manualshive

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Summary of Contents for Revox B740

Page 1: ... QJOEM R OX SERVICEANLEITUNG SERVICE INSTRUCTIONS i TRUCTIONS DE SERVICE 20 10 0 J S 1 R OX B74a srtAEO powsfl AMPuinen IMVf C6FT UFVCL nGHT LtVEL L TT CHAN CHANNCL i iJil J1 n Nb RCVO f II ...

Page 2: ...s D yisiaRs R ox B740 SERVICEANLEITUNG SERVICE INSTRUCTIONS INSTRUCTIONS DE SERVICE ...

Page 3: ...t description the electrical adjust ments as well as schematic diagrams con tain all informations concerning the A740 snd B740 versions INTRODUCTION Ce livre st une nouvelle Edition de I instruc tion deservicepourl amplificateurde puis sance Revox B740 Onatenu compte des modifications etdes innovations La description des fonctions I ajustage el la section schema contiennent lous les indi cations p...

Page 4: ...STOllISEin ReVoX B740 3 6 Schaltbilder 6 1 6 Diagrams 6 1 6 Schemas 6 1 ...

Page 5: ...the opened amplifier discharge the filter ca pacitors as described in section 2 2 of this manual 1 1 Technical specifications Continuous average sine wave power from 20 20 000 Hz at rated distortion 1 75 W per channel into 4 ohms 100W per channel into 8 ohms both channels simultaneously driven Damping factor minimum 150 1 kHz 8 ohms Frequency response 20 20 000 Hz plus 0 minus 0 75 dB Subsonic fil...

Page 6: ...sockets B binding posts 60 amps Headphone output stereo jack on from panel nominal output voltage 11 9 V output impedance 100 ohms Suitable for low and high impedance phones Output level meters 2 peak program meters internally illumi nated response time 2 5 msec fora 1 dB indi cation release time 1 8sec 20dB linear dB scale from 40 to 5 dB 0 dB equals 100 W into 4 ohms meter dimensions 95x73 mm El...

Page 7: ...sprechergruppen Sctialtec SPEAKERS A Output selector SPEAKERS A Commutateur haut parleur SPEAKERS A Lautsprechergfuppen Schalter SPEAKERS B Output selector SPEAKERS B Comrrulateur haut parleur SPEAKERS B Eingangswahlschatler INPUT INPUT selector Selecteur d entree INPUT F gelregler linker Kanal LEF LEVEL Input attenuator LEF LEVEL Reglage du niveau canal gauche LEF LEVEL Pegetregle rechter Kanal R...

Page 8: ...CANNON B caral gauche Ausgange SPEAKERS Sorties SPEAKERS Outputs to SPEAKERS D IN Lautsprecherbuchse SPEAKERS A rechter Kanal DIN sccket SPEAKERS A right channel Prise haut parleur DIN SPEAKERS A canal droit DIN Lautsprecherbjchse SPEAKERS A linker Kanal DIN socket SPEAKERS A left charnel Prise haiit parleur DiN SPEAKERS A canal gauche Laiflsprecher Polklemmen SPEAKERS B rechter Kanal Binding post...

Page 9: ...ove to wards the rear 2 2 Discharging the filter capacitors Remove top cover as per section 2 1 Amplifier must be disconnected from the electric current supply Important Do not try to discharge Vie capacitors by simply short circuiting the bus bars Create an electrical connection using a screwdriver between TP5 and 1 2 V in the power supply 1 068 734 as indicated in figure 2 1 1 After having made ...

Page 10: ...en Platte Sind nun zugSnglich AnmerKung Die Helligkeit der beiden Lampen ist vor dem Zusammenbau der Instrumente auf identische Leuchtstarke zu prufen 2 4 Removal of front panel Pull knobs from the three toggle swit ches Bring switches into their OFF position Remove front toe rail Remove 2 screws 24 on the bottom Remove four screws 25 on the from pennei Take holdof the two handles and carefully pu...

Page 11: ... of output stages and pream plifier boards Remove output stages with their heat sinks as per section 2 3 Disconnect all plug in wire connections from both printed wire circuits Remove heatsink of driver stages Undo two screws at the side of the cooling fins Unplug connections of the NTC resistor Pull the heat sinks with their transistors from the plug in connections in the printed circuit board Re...

Page 12: ...res from the bus bars on the filter capacitors Disconnect three plug in connections from the power supply board Remove four screws Lift power supply out of the unit 2 11 Removal of meter amplifier Remove top cover as per section 2 1 Disconnect one plug in connection Remove two screws 28 on the bottom 2 12 Removal of filter capacitor Remove top cover as per section 2 1 Disconnect and remove bus ber...

Page 13: ...am plifier stage The input attenuators permit accurate level adjustments for each channel in steps of 3 dB over the range frorn 0 to 27 dB In po sition OdB and with a signal input of 1 volt the amplifier will deliver 175watts into 4 ohms load Alter 7 5 dB of amplification in the pream plifier the signal passes the subsonic filter followed by a phase linear tow pass 75 kHz from where it reaches the...

Page 14: ...cond temperature threshold If frie temperature continues to rise to 120 C on the output transistor heat sinks or to 150 C in the power supply the crowbar circuit becomes activated That circuit cau ses a thyristor to become conductive thereby short circuiting the filter capaci tors of the power supply with the effect the amplifier s main fuse blows Loudapeakdr protection If a signal condition of 3 ...

Page 15: ... 1C 1 the threshold voltage is set to 7 7V approx As soon as this potential is exceeded on pin 2 then pin 1 ICl flips to positive 12 V approx the transistors Q1 and 04 become conductive causing C6 to get charged and the Diac D21 fires the thy ristor SCRI which causes a short circuit across the filter capacitors The amplifier s main fuse blows thereby disconnecting the amplifier from the electric c...

Page 16: ...of 2 7 The response time for the me ters is determined by R13 C3 and R51 C4 respectively The return time is governed by the combination of R14 R15 C3 and R52 R53 C4 respectively The linearity of the re turn time can be adjusted with RIB R56 The next IC amplifier which has diode 09 D19 in Its feedback loop forms the loga rithmic circuit to process the signal arriving from the rectifier For referenc...

Page 17: ... the amplifier s top plate as per section 2 1 Work carefully on the open amplifier and take great care 10 preventthe possibility of a short circuit across the bus bars on the filter capacitors 4 2 Adiustment of stabilized supply voltages fig 4 2 1 Connect power cord to electric current supply and switch the amplifier on Connect digital voltmeter to TP4 and TP3 0 0 V on the power supply board 1 068...

Page 18: ... 25 mV Convoler qu aux bornes des resistances R59 R60 R61 R62 R63 la tension soil egalement de 26 mV 50 Si la tension sur ure des resistances est mauvaise rSajusleravec R25 et recontrSler touies les resistances Ajuster de la m me fagon le canal droit 4 4 Pegelkontrolle Ausgang unbelaStet Ruckseitige AusgSnge Bedisnungsslemente nach Fig 4 4 1 ein stelien NF Volimeter an Ausgang LEFT CHAN NEL 18 ans...

Page 19: ...R must read 2 37V Headphone output Connect audio voltmeter to headphone jack PHONES 2 Connect audio generator to a suitable in put socket and adjust it to deliver 1 V at 1kHz Voltmeier must Indicate 11 9 V Volume control Turn input selector 5 to position B DI RECT Connect audio generator to input LEFT CHANNEL 14 with its Signal output set to 1 V at 1 kHz Adjust generator level to obtain an oulput ...

Page 20: ...o output LEFT CHANNEL 18 Connect audio generator to input LEFT CHANNEL 14 Select the frequency of 1 kHz and adjust input level to obtain a reading of 20 V at the amplifier s output Adjust trimport R33 LEFT on the meter amplifier until an indication of OdB exact is obtained on the left PPM Reduce input level by 30 dB Adjust irimpot R35 until an indication of 30 dB is obtained on the left PPM Reduce...

Page 21: ... completed first Required test instrument Signal Burst Generator similar to GenRad GR1396B Connect signal burst generator to input RIGHT CHANNEL 13 Select the frequency of 37 5 Hz and ad just input level to obtain a level of 20 V at the amplifier s output 0 dB on the PPM Onthesignalburstgeneretorselectanoff period of 128 cycles and a pulse length of approx 2 seconds Adjust the meter s return time ...

Page 22: ...ANNEL 12 L vel IV Frequency 1 kHz Adjust input level to obtain a full dB read ing On trie audio voltmeter e g 0 dB on the 30 V range Check response characteristics of sub sonic filter Frequency Attenuation 20 Hz I BdB 0 5 dB 16 Hz 3 d8 1 0dB 10Hz 9 dB 1 5dB Check frequency characteristics of high frequency filter Frequency Attenuation 75 kHz 3dB 0 2dB 1 00 kHz 8dB hO 2dB Connect audio voltmeter to...

Page 23: ...stant between i 0 0 75dB Connect audio voltmeter to output RIGHT CHANNEL 17 Connect audio generator to input RIGHT CHANNEL 13 Repeat the above described measure ment on the right channel as well 5 3 Harmonic distortion output loaded Adjust operating controls as per fig 5 2 1 Connect distortion analyser to output LEFT CHANNEL 18 Connect audio generator to input LEFT CHANNEL 14 and adjust input leve...

Page 24: ...under test with a 10 kohm resistor Measure signal to noise ratio through a CCIR weighting filter The so measured signal to noise ratio must be not less than 100 dB with reference to the above men tioned output level of 26 6V Connect audio voltmeter to output RIGHT CHANNEL 17 and audio genera tor to input RIGHT CHANNEL 13 Repeat the above described measure ment On the right channel as well Turn inp...

Page 25: ...ect audio generator to input RIGHT CHANNEL 13 while transferring the 10 kohm terminating resistor to input LEFT CHANNEL 14 Adjust level from audio generator to ob lain again a reference deflection on the audio voltmeter e g 0 dB on 30 V range Transfer audio voltmeter to the output LEFT CHANNEL 18 and measure the le vel of the signal crosstalking Into the right channel Measure crosstalk at 40 Hz an...

Page 26: ...2 MAINS TRANSFORMER UNIT 1 068 612 6 3 MAINS SWITCH PCB 1 168 740 6 3 POWER SUPPLY PCB 1 068 734 6 4 SWITCH BOARD 1 068 735 6 7 PREAMPLIFIER PCB 1 063 733 6 8 POWER AMPLIFIER PCS 1 068 741 6 10 MU METER AMPLIFIER PCB 1 068 736 6 13 CONNECTION PCB 1 088 738 6 13 11 80 ...

Page 27: ......

Page 28: ......

Page 29: ...15 9 80 ...

Page 30: ...1 5 9 80 ...

Page 31: ...1 5A 100mA 7SV loom 7SV S8 S 6V NOOmW lOOmA 7Sv 100 75V 0 3S0V I 5A lOOvA 7SV 00 A 7SV 00 A 7SV 58 5 6V 600M 100mA TSV 50 03 0606 50 03 0693 50 03 0667 50 05 0315 50 03 0667 50 03 0686 50 03 0361 50 03 0667 50 03 091S 50 03 0667 50 03 0686 SO 03 0561 BC1076 NPNt 30V 100m NP 300V 100mA PnP 00V 100mA hPN 300V lOOmA 0CS6O0 PNP NPN 300V 100mA PNP 300V 100mA NPN lOOV lOON NPn 300V 100mA eCS6O0 PNP NPN ...

Page 32: ......

Page 33: ...B740 SECTION 6 8 SWITCHBOARD 1 068 735 SPECIF C rinNS EOirlvPLENT 15 9 80 ...

Page 34: ...toa 57 41 4 03 57 41 4223 57 34 47Sl 57 34 4741 S7 34 7Sfil 57 34 7S0I 57 41 4142 207 16V T 0 UV ft 5 50V C 5 SOV C lot 16V 61 0 lOVr Id 2fi7 16Vr la 5X IOOV Hpc 5Xr lOOV ROC 20t 16V fa 5 50V C 5X 50V Ca 57 SOV Ct IOO A 75V 1001 4 75V 57 AOOpM 5t AOOpM eC560 PNP 1o eC550C IPN To ocsoeo PNP 5C550C NPN acsaoc ptip BC5S0C NPN 5S 2S f Cf 5t 25M Cf 57 2SM 7 5 25Nr Cf 5S 25H C7 IX 25M f IX 25N nr IX 25N...

Page 35: ......

Page 36: ...SECTION 6 11 TryfraSH 1 1n r In jU 1 4 1 liW i ttsv l i II b 1 j IM 11 Tswat 1 1 jM 1 BHk Pg K bH OOV C 1 X D I X i JUMPER JS 1 PLUGED FOR USE IN A68 SYM INPUT REMOVE FOR USE IN B740 ASYM INPUT 29 8 80 ...

Page 37: ...48 614 00 2 2 un L 62 02 llOi 100 UH lOt 3 0 1 50 03 0306 aci788 8C307B ftNP MOT FH SIE 0 2 50 C3 0409 8C1088 802378 8CI07I NftN MOT FH S10 0 5 50 03 0492 8C2558 60V PNP 177 SJE Q 50 03 0491 8C1748 60V NPN tTT SlE Q 5 50 03 0475 260 46 80139 NPN P OtP 1 lO ITT SlE Q 4 50 03 0479 2SA 46 80140 MNP Not9 1 70 177 5IE 0 T 50 03 0345 2N6476 pop N t9 1 MCA Q P 50 03 0344 2N6474 npn Not9 1 ftCA 0 50 03 04...

Page 38: ...SECTtON 6 13 BTTILDC1I11M3 B740 VU METER AMPLIFIER PCB 1 068 736 15 9 80 DV DS DI3 018 1NLLif8 D9 D11 D19 D21 WkW62 IC1 IC1 RCW36 ...

Page 39: ... Typing SECTION 6 14 VU METER AMPLIFIER PCB 1 068 736 A 4 tc 1 A A S i S TP2 15 9 80 S 1 b C I S0 39 K MA NgTCB BCAAO 1 069 t 6 00 RAC ...

Page 40: ...turer WILLI STUDER CH 8105 Regensdorf Switzerland Althardstrasse 30 STUDER REVOX GmbH D 7827 Loffingen Germany Talstrasse 7 Worldwide Distribution REVOX ELA AG CH 8105 Regensdorf Switzerland Althardstrasse 146 ...

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