Sphinx-Project18-pwr-sm2 维修电路原理图.pdf

1. SERVICE MANUALPROJECT EIGHTEENTRUE DUAL MONOPOWER AMPLIFIERRadioFans.CN 收音机爱 好者资料库SPHINX Project Eighteen Service Manual 2 1. UNPACKING.32. SPHINX WARRANTY CARD .33. CONTACTING THE MANUFACTURER.34. THE POWER AMP AT A GLANCE.4Front panel.4Rear panel .55. TECHNICAL SPECIFICATIONS.66. GENERAL CHECKLIST.7Optical connections .7Switching the amp on.7Protection mode.7Shorted output .7Cables.77. ADJUSTMENT PROCEDURES.8High Bias .8Low Bias .9Offset .9Common Mode .108. PROBLEMS AND SOLUTIONS.119. DIAGRAMS AND PARTS LISTS .12Connecting diagram for testing the project 18.13Connection diagram for common mode adjustment.14Schematic layout of all relevant parts.15Schematic overview of the Project 18 mainboard.16Project 18 logic .17Project 18 supply & relay control schematic.18Project 18 blockdiagram left .19Project 18 blockdiagram right .20Project 18 amplifier diagram left .21Project 18 amplifier diagram right.22Project 18 power supply left.23Project 18 power supply right.24PCB drawings of Project 18.25Partlist.26RadioFans.CN 收音机爱 好者资料库SPHINX Project Eighteen Service Manual 3 The Sphinx Project Eighteen designThe Sphinx Project Eighteen was designed for theever-increasing group of quality-consciousaudiophiles.We are very proud of the tradition connected withthe SPHINX name, especially concerning audioquality perfection.This service manual will help you to optimallyservice and repair the Sphinx Project Eighteen TrueDual Mono Power Amplifier.The power amp handles the largest signal peaksand transients with ease, and has no problem withany size and type of loudspeaker load: even themost demanding.These characteristics are the result of several newtechnologies and components. For instance theunique power supply which assures a stable andnoise free operation. The special toroidaltransformer (one for each channel!) of 650 VA hasthe size of a 1000 VA model: safely over-specified.Thanks to the generous energy reserve of 66,000F (formed by 30 capacitors in parallel), unlimitedpower is available for the largest signal peaks.Furthermore there are three completely separatepower supplies for the input section, driver sectionand the logic and indicator section.Much attention has also been paid to the physicallayout, the positioning of components and theinternal grounding. This results in a equivalent inputnoise value of 1 V (-120 dBV): remarkable for apre-amp, but really astounding for a big power ampwith two transformers.All of this means that the Project Eighteen can workwith all kind of loads from every loudspeaker: eventhe most difficult ones like electrostatic andmagnetostatic.To obtain the maximum quality from this power ampit is necessary to use it with top quality audiocomponents preferably with other Sphinxcomponents.1. UNPACKINGBefore leaving the factory every Project Eighteen issubjected to stringent and extensive technical andexterior quality inspections. This ensures the usermany years of high quality audio from a perfect-looking product.Attention: The power amp weighs over 24 kg!Never lift it out of the box without someonehelping you.We recommend owners to ship the ProjectEighteen in its original carton.After unpacking the Project Eighteen we thereforerecommend you carefully check it for any transportdamage.If you find any damage and the product has notbeen shipped in the original carton the ensuingrepair costs will not be covered by the warranty.2. SPHINX WARRANTY CARDTo be entitled to any warranty repairs the ownermust have send the filled out warranty card toSphinx or a distributor where it has been registered.Other regulations may apply in your specificcountry: when in doubt, please consult the properauthorities.3. CONTACTING THE MANUFACTURERIn case of any problem not covered in this manualor if you have other questions you may contact theSphinx International Service Department in TheNetherlands (local time: GMT +1h) during officehours at the following numbers:Telephone(+31) 35 602 0302Fax(+31) 35 602 2806E-mailaudionleuronet.nlIt is always very helpful and efficient if you have allrelevant information about the specific product andthe problem ready.Please also refer to the User Manual of theProject Eighteen for information aboutfunctions not described in this manual.It is important to familiarise yourself with thespecial functions, operation and possibilitiesof the Sphinx Project Eighteen.SPHINX Project Eighteen Service Manual 4 4. THE POWER AMP AT A GLANCEFront panel1. LED: Indicates the selected function:stand-byredongreen2. STANDBY: To switch the component on and off.12SPHINX Project Eighteen Service Manual 5 Rear panel3. RIGHT OUTPUT: To connect the cable from theright loudspeaker:red+white-4. CONTROL IN: To connect the optical cablefrom another Sphinx component like a pre-amp.5. BALANCED RIGHT: To connect the XLR cable(balanced cable) from the right output of thesignal source.6. CINCH RIGHT: To connect the cinch cable fromthe right output of the signal source.7. CINCH/BALANCED INPUT: With this switchyou may select between the inputs:upunbalanced (6 and 8)downbalanced (5 and 9)8. CINCH LEFT: To connect the cinch cable fromthe left output of the signal source.9. BALANCED LEFT: To connect the XLR cable(balanced cable) from the left output of thesignal source.10. CONTROL OUT: To connect the optical cablegoing to another Sphinx component.11. LEFT OUTPUT: To connect the cable from theleft loudspeaker:red+white-12. ON/OFF: This is the mains power switch.13. AC POWER: Connect the power amp to amains outlet (230 - 240 VAC).The mains fuse is placed behind the cover.14. Manufacturers label: This shows importantdata for the component, such as serial numberand mains power voltage.3456 7891011121314SPHINX Project Eighteen Service Manual 6 5. TECHNICAL SPECIFICATIONSBandwidth0 100,000 Hz (+0/-1 dB)Phase response error2x 160 W into 8 ohm (22.0 dBW), THD 2x 280 W into 4 ohm (24.5 dBW), THD 2x 420 W into 2 ohm (26.2 dBW), THD 0.01%Output voltage / current, max.36 V / 43 ATHD+N (IHF-A)0.01% (1 W into 8 ohm, 1 - 20,000 Hz)IMD120 dBCommon Mode Rejection Ratio80 dB ( 100 Hz)Slew rate50 V/sDamping factor2000 (1 20,000 Hz)InputXLR balanced / cinch WBT unbalanced level, nominal1.25 V (1.9 dBV) / 1.25 V (1.9 dBV) impedance600 ohm / 20 kohmSupply capacitance132,000 F totalPower consumption1500 W max. (70 W standby)Power transformer, primary230 VAC / 115 VAC secondary 1 & 242.5 V / 7.1 A secondary 3 & 415 V / 1 A secondary 5 & 660 V / 0.1 AMaximum DC-offset+0.5 V and 0.5 VShort circuit protectionFuse per channelDimensions (h x w x d)143 x 482 x 452 mmWeight24 kgThis unit conforms to the EMC interference regulations issued by the EU and to the CE standards.This unit complies with safety regulation VDE 0860 and therefore with international safety regulation IEC 65.Technical specifications may be changed by SPHINX without prior notice if technical developments make thisnecessary.SPHINX Project Eighteen Service Manual 7 6. GENERAL CHECKLISTBefore you test or service the Project Eighteenplease check the following items. They will giveinformation about the current status of the amplifier.Note: The Project Eighteen will become warm, socorrect placement is critical. Do not position it ontop of or close to other heat-radiating equipment(such as other power amps) or in direct sunlight.Please ensure unrestricted ventilation aroundthe component.Optical connectionsThe optical CONTROL IN (4.) is light-sensitive. Astrong light source might therefore activate theCONTROL function and switch the Project Eighteento Standby.While this mode has priority the amplifier can notbe activated with the Standby switch at the frontpanel.Before you start connecting equipment it is alwayswise to check whether all the mains cables of allcomponents are disconnected from the mainsoutlets!This will prevent any damage to the loudspeakersand amplifiers caused by incorrect wiring orsettings.Connect the mains cable after you have connectedall other components in the system and havedouble-checked all connections.Switching the amp onBefore you switch the power amp on you shouldalways first: connect a pre-amp connect the pre-amps Control Out to the poweramps Control In or place the dummy plug in the Control INconnectorAfter switching the amplifier ON it will selectStandby mode and the following will happen:.1. The output relays are disconnected.2. The input relays are disconnected.3. The Control Out will show a red light.4. The biasing relays reset the bias current tostandby level.5. The red LED (1.) will light.Pressing the Standby-button (2.) will activate theamplifier and the LED turns to green.Protection modeIf at any time the output DC-offset exceeds 500 mVthe protection mode will activate.This will reset the amp to Standby mode and thegreen LED (1.) will change to red.Note: Externally there is no way of telling whetherthe amp is in protection or standby mode!This can only be checked inside the housing: LEDLD 102 will be illuminated in protection mode.The protection mode can only be deactivated byreadjustment of the DC offset voltage (according tothe procedure “Offset” at page 9).Shorted outputIf one of the outputs is shorted the fuse F203,F204, F403 or F404 will blow.CablesAlways use loudspeaker and audio cables andconnectors of the highest quality.Siltech cable is used throughout internally and werecommend using this same cable for all externalconnections.If you have the choice between longer loudspeakercables or longer audio cables, choose the latter(cables between pre-amp and power amp willcause the least signal quality loss).SPHINX Project Eighteen Service Manual8 7. ADJUSTMENT PROCEDURESThe Project Eighteen has eight adjustable settings,meaning four adjustment procedures per channel:1. High Bias: to set the bias current of the power-transistors for normal use2. Low Bias: to set the bias current of the power-transistors for standby mode3. Offset: to set the minimal DC voltage for theoutput4. Common Mode: to maximise the commonmode rejection of the balanced inputRe-adjustment of one or more might be necessarydue to ageing or when parts have been replaced orrepaired.After removing the top cover plate you will clearlysee the two separate channel sections.High BiasWith this procedure you set the proper bias level forthe power transistors. This ensures their Class Aoperation at low power levels.Connect the amplifier according to the drawing“Connecting diagram for testing the project 18”(page 13).The input of the amplifier must be shorted (by wayof the MUTE function of the oscillator). Switch the amplifier ON (not in StandbyMode!) and wait until it has reached the properoperating temperature (this takes an hour). Set the millivolt-meter to the DC-range. Place the two measuring clips of the meteracross one of the emitter resistorsLeft Channel: R468, R469, R472, R473, R476,R477, R480 and R481.Right Channel: R268, R269, R272, R273, R276,R277, R280 and R281 (see schematic at page15). The level should be 60 mV DC (3 mV).If not: adjust potmeter P402 (Left) or P202(Right) until the level is 60 mV. Switch the oscillator on and set it to 1 kHz and alevel of 0 dBu. Check the distortion with a THD analyser: itshould be at the specified value (0.01% IHF-A 1 kHz). If this is correct the procedure is finished. You may now switch off the amplifier orcontinue with another adjustment procedure.Attention:When re-adjusting any setting please ensure thatthere is no loudspeaker connected to the output!Otherwise the loudspeaker may be seriouslydamaged.Attention:The amplifier is able to generate high outputvoltages of over + or -60 V.Please be very careful during the adjustments!Attention:All emitter resistors should show the same 60 mVvalue. If not, the corresponding power transistor maybe defective.SPHINX Project Eighteen Service Manual9 Low BiasWith this procedure you set the proper bias level sothe power transistors will remain at operatingtemperature during standby mode.If this setting is too low, the operating temperaturewill drop too much causing an unnecessaryincreased warm-up period after switching the ampon.If this setting is too high the amplifier will consumemore electrical power than necessary.Connect the amplifier according to the drawing“Connecting diagram for testing the project 18”(page 13).The input of the amplifier must be shorted (by wayof the MUTE function of the oscillator). Switch the amplifier ON (but in StandbyMode!) and wait until it has reached the properoperating temperature (this takes an hour). Set the millivolt-meter to the DC-range. Place the two measuring clips of the meteracross one of the emitter resistorsLeft Channel: R468, R469, R472, R473, R476,R477, R480 and R481.Right Channel: R268, R269, R272, R273, R276,R277, R280 and R281 (see schematic at page15). The level across each resistor should be 5 mVDC (0.25 mV).If not: adjust potmeter P403 (Left) or P203(Right) until the level is 5 mV. Then switch the amplifier ON (LED is green). Switch the oscillator on and set it to 1 kHz and alevel of 0 dBu. Check the distortion with a THD analyser: itshould be at the specified value (0.01% IHF-A 1 kHz). If this is correct the procedure is finished. You may now switch off the amplifier orcontinue with another adjustment procedure.OffsetThe Offset adjustment procedure minimises the DCoffset value of the amplifier output. This DC offset isimportant when capacitive loads are used, such aselectrostatic loudspeakers. These loudspeakersoften use a very low-impedance step-uptransformer. The amplifier sees this load as ashort to the DC voltage.Connect the amplifier according to the drawing“Connecting diagram for testing the project 18”(page 13).The input of the amplifier must be shorted (by wayof the MUTE function of the oscillator). Switch the amplifier ON not in Standby Mode!)and wait until it has reached the properoperating temperature (this takes an hour). Set the millivolt-meter to the DC-range. Place the measurement clips of the meter overthe output terminal. The level should not exceed +5 or -5 mV DC.If not: adjust potmeter P404 (Left) or P204(Right) until the level is within this range. Switch the oscillator on and set it to 1 kHz and alevel of 0 dBu. Check the distortion with a THD analyser: itshould be at the specified value (0.01% IHF-A 1 kHz). If this is correct the procedure is finished. You may now switch off the amplifier orcontinue with another adjustment procedure.Attention:Be careful not to trip the offset protection mode. Itwill activate when the output DC offset exceeds+/-500 mV.This is indicated by Internal LED LD 102.This mode will be reset if the DC offset is adjusted towithin the proper limits.Please be careful during the adjustments!SPHINX Project Eighteen Service Manual10 Common ModeThe Common Mode adjustment procedureminimises the amplification error of the (internal)differential amplifier.If the balanced input amplifier receives an identicalsignal at the normal (+) and inverted (-) inputs theoutput signal will be zero. This helps to reduce theeffect of externa