Sphinx-Project8-pre-sm 维修电路原理图.pdf
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1、SPHINX Project Eight Service Manual1 ASERVICE MANUALPROJECT EIGHTREFERENCEPRE-AMPARadioFans.CN 收音机爱 好者资料库SPHINX Project Eight Service Manual2 1. UNPACKING.32. SPHINX WARRANTY CARD .33. CONTACTING THE MANUFACTURER.34. TECHNICAL SPECIFICATIONS.45. GENERAL CHECKLIST.5Serial number and software version
2、.5Input functions .5Channel imbalance.5Remote Control.56. SPHINX REMOTE CONTROL.6Buttons and LED indication .6Operation.7Selecting without switching.7Learning the commands.7Changing a command.7Erasing all commands of one component.7The LED during Normal mode.8The LED during Learn mode.8Batteries.8Ot
3、her things worth knowing. .8Encountering problems.87. MEASUREMENTS .9General set-up.9Necessary Equipment.9Audio signal distortion measurement.9Set-up .98. OUTPUT DC-OFFSET ADJUSTMENT.10Set-up .10Adjustment.109. PROBLEMS AND SOLUTIONS.1110. DIAGRAMS AND PARTS LISTS .12Figure 1: Front panel .12Figure
4、2: Rear panel.12Index of diagrams and drawings.13Figure 3: Connection Diagram for testing the Project Eight.14Figure 4: Display Board Schematic Layout.15Figure 5: Construction Drawing for top cover plate.16Figure 6: Schematic Operational Diagram Project Eight .17Figure 7: Schematic Overview of all r
5、elevant potentiometers.18Figure 8: Disamp-96 .19Figure 9: Functional Schematic .20Figure 10: Left Power Supply.21Figure 11: Right Power Supply .22Figure 12: Input/Output.23Figure 13: Left Volume Control.24Figure 14: Right Volume Control.25Figure 15: Left Output Amp.26Figure 16: Right Output Amp.27Fi
6、gure 17: Left Input Amp .28Figure 18: Right Input Amp.29Figure 19: Power Supply Unit .30Figure 20: PCB drawings.31Parts List.32RadioFans.CN 收音机爱 好者资料库SPHINX Project Eight Service Manual3 The Sphinx Project Eight designThe Sphinx Project Eight was designed for theever-increasing group of quality-cons
7、ciousaudiophiles.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 EightReference Pre-Amp.This Reference pre-amp uses the newesttechnologies and refined d
8、esigns and is extremelysimple to operate.Features include ultra-linear extremely low-noiseClass A audio circuits, built from the finest hand-selected parts.The signal path is completely balanced from inputto output, and left and right are totally separated.Volume and balance controls are achieved by
9、means of precision relays, as is the input selection.All settings and controls can also be accessed fromthe supplied Sphinx Remote Control.To obtain the maximum quality from this pre amp itis necessary for it to be properly aligned and to beused with top quality audio components, preferablyother Sph
10、inx components.1. UNPACKINGBefore leaving the factory every Project Eight issubjected to stringent and extensive technical andexterior quality inspection. This ensures the usermany years of high quality audio from a perfect-looking product.We recommend owners to ship the Project Eight inits original
11、 carton.After unpacking the Project Eight 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 ensuringrepair costs will not be covered by the warranty.2. SPHINX WARRANTY CARDTo be entitled to any w
12、arranty 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 thi
13、s 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 ha
14、ve allrelevant information about the specific product andthe problem ready.Please also refer to the User Manual of theProject Eight for information about functionsnot described in this manual.It is important to familiarise yourself with thespecial functions, operation and possibilitiesof the Sphinx
15、Project Eight.SPHINX Project Eight Service Manual4 4. TECHNICAL SPECIFICATIONSBandwidth0 - 500,000 Hz (+0/-3 dB)Phase response error1Gain20 dB max.THD+N (IHF-A)0.008% (2nd harm., 100 kHz and 6 V into 600 ohm)0.0015% (2nd harm., 10 20,000 Hz and 6 V into 600ohm)IMD110 dBChannel separation110 dBInputs
16、2x XLR balanced6x WBT cinch unbalanced Level, nominal (for 1 V output)0.16 V (-18 dBV) ImpedanceXLR: 10 kohm / cinch: 50 kohm Sensitivity (programmable for each input)adjustable between 9 dB and +9 dBOutputs2x XLR balanced1x WBT cinch unbalanced1x cinch Tape level10 V max. (20 dBV) (1 - 100,000 Hz,
17、THD 0.001%) impedance1 M)? 2x non-inductive load resistor 8 / 250 W? 1x harmonic distortion analyser(internal distortion 60 MHz)? 1x connection unit / switch box(to connect resistors and amp outputs todistortion meter)Note: See drawing 4. for construction details.? 2x shorting connector(for balanced
18、 pre-amp inputs)? 2x balanced cable set(to connect distortion meter, pre-amp andpower amp)? 1x special top cover plate (preferablytransparent) with holes for adjustment toolsNote: See drawing 5. for construction details.? A two channel DC-coupled power amplifier (e.g. Project Eighteen)Audio signal d
19、istortion measurementBefore adjusting the Project Eight please firstmeasure the total harmonic distortion at the audiooutput. The measured value is an indication of thecurrent state of the Project Eight.Set-upFor the correct measurement set-up please refer tofigure 3 at page 14.? Set the oscillator
20、output level to 0.775 V(0 dBu).? Adjust the pre-amp volume control so thatoutput level equals input level (0 dBu).? THD should now be 0.1% unweighted (or0.013% IHF-A).? Now set volume control to maximum (fullyclockwise).? Increase the oscillator output of the distortionanalyser to set the pre-amp ou
21、tput just beforeclipping.? THD should now be 0.12% unweighted (or0.005% IHF-A).SPHINX Project Eight Service Manual10 8. OUTPUT DC-OFFSET ADJUSTMENTProper DC-offset adjustment is very important.A simple trick will greatly increase the accuracy ofthis critical adjustment (see also the drawing titled“
22、Connection Diagram for testing the Project Eight”at page 14 ).By connecting a DC-coupled power amp to theProject Eight outputs and measuring the offset atthe speaker outputs, the offset is boosted to around30 times the original value!Note: We strongly recommend that you use apower amp with a very lo
23、w DC-offset, such as theProject Eighteen.Note: The pre-amp and the power amp should beswitched on at least 1 hour before performing thisadjustment so they can reach optimum workingtemperatures.Set-up? Connect a distortion analyser input and a DCmV-meter to a pre-amp output (or to the powerampifier).
24、 The correct pre-amp output will bementioned later.? Connect the distortion analyser output to a pre-amp input, the correct input will be mentionedlater.? Switch off the oscillator of the analyser, this willshort-circuit the pre-amp input.? Remove the top cover of the Project Eight andreplace it wit
25、h the special cover plate (withadjustment holes, see figure 5 at page 16).AdjustmentFor the actual adjustment you may refer to Figure20 (Main PCB drawing) at page 29 and Figure 7(Schematic overview of all relevant potentiometers)at page 17.In Figure 6 (Schematic operational diagram ofproject Eight)
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