Hafler-DH500-pwr-sm维修电路原理图.pdf

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1、_.,_._. ,.-I_THEPOWER AMPLIFIERfor ASSEMBLYand OPERATIONCAUTION: IF THE FUSES BLOW,SOME DISTORTED SOUND CAN BEHEARD. THEREFORE IF AMPLIFIERMALFUNCTIONS, ALWAYS CHECKFOR BLOWN FUSES FIRST.LM153$3.00THE DAVID HAFLER COMPANY5910 Crescent Boulevard, Pennsauken, New Jersey 08109Please refer to this seria

2、lnumber in all communicationsregarding this equipment.RadioFans.CN 收音机爱 好者资料库DH-500Power Rating: Less than 0.025% total harmonic distortion at any power level up to 255watts continuous average power per channel into 8 ohms at any frequency between20 Hz and 20 kHz with both channels driven.IM Distort

3、ion (SMPTE): Less than 0.007% from 1 watt to 255 watts into 8 ohmsTypical THD at 255 watts into 8 ohms: 1 kHz-0.002%; 10 kHz-0.007%Frequency Response into 8 ohms: -3 dB, 0.5 Hz to 120 kHz at 1 wattkO.5 dB, 5 Hz to 40 kHz at 255 wattsTypical Channel Separation at 1 kHz: 60 dBSignal to Noise Ratio: Ex

4、ceeds 100 dB referred to 255 watts into 8 ohms, unweightedExceeds 90 dB referred to 1 watt into 8 ohms, A weightingInput Impedance: 47,000 ohmsInput Sensitivity: 2.35 volts for 255 watts into 8 ohms; 0.145 volts for 1 wattDamping Factor: 200 to 1 kHz into 8 ohms; 60 to 10 kHz into 8 ohmsRise Time: 1

5、0 kHz, 80 volts p/p square wave, 10% to 90%: 2.5 us.Slew Rate: 1 kHz, 120 volts p/p square wave: 45 V/us.Semiconductor Complement: 27 transistors, 12 power Mosfets, 33 diodes, 8 zener diodes,one integrated circuit, one diode bridge.Power Consumption: 240 VA quiescent; 1200 VA rated power into 8 ohms

6、, 2 channelsSize: 7-l/4” high, 19” wide, 13” deep including handlesNet Weight: 45 lbs.Shipping Weight: 49 lbs.CAUTION: For continued protection, replace the power fuse only with the same type and ratingas indicated.WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS EQUIPMENTTO RAIN OR MOIS

7、TURE.0 Copyright 1987. All rights reserved.RadioFans.CN 收音机爱 好者资料库INTRODUCTIONThe Hafler DH-500 is a two channel audio poweramplifier designed to the very highest performance stan-dards. It is available as a kit, or factory assembled. Itspower rating of 255 watts per channel is very conservative,and

8、 it can deliver appreciably higher powers into impe-dances below the rated 8 ohms. You must be very cautiousin the application of this amplifier, as its output capabilityis more than most speakers can safely tolerate. We urgeyou to read the “Operation” section of this manual so yourspeakers will be

9、reasonably protected. The best protectionis still common sense in choosing program levels whichyour speakers can tolerate.The DH-500 combines power MOSFET technologywith a uniquely simple and effective circuit which reducesall types of distortion at all power outputs, over the entireaudio spectrum,

10、to levels where the finest test equipmenthas great difficulty in measuring it. The DH-500 sets a newhigh in reliability and resistance to abusive operating con-ditions at such high powers. This is one of the direct ben-efits of the power MOSFET s ability to current limit underabnormal conditions.Whe

11、re the conventional bipolar transistor must be pro-tected by special circuits from entering “thermal runa-way” when it gets hot due to heavy signals, tending to geteven hotter, the MOSFET self-corrects to reduce the cur-rent, and thus the heat under the same conditions. Youthus gain the dual advanta

12、ges of simpler circuitry and theelimination of one of the chief causes for distorted signalsimposed on the music-the sound of the actuation of com-plex protective circuits.The speed-measured as the slew rate-of the DH-500delivers unmatched transient linearity, revealing the mostdelicate nuances of t

13、he music. In refining the basic HaflerMOSFET circuit the overall open loop gain was reducedby using more local feedback in the input stage. This re-quired less compensation to stabilize the circuit, with theresult that it was faster overall. With the built in bandwidthlimitation at the input, all ot

14、her stages are free of any trans-ient overload.The fully complementary, symmetrical push-pull circuitis direct coupled throughout (except at the input). It usesall silicon discrete devices in a format which is directly re-lated to the acclaimed Hafler preamplifier circuit. With itsunconditional stab

15、ility into virtually any load, and itsenormous power capability, the result is complete freedomfrom listening fatigue. The longer you listen to this re-markable amplifier, the more certain you will be that youcould not have made a better choice.While modest in cost, through the elimination of frills

16、and gadgetry, the quality is evident not only in the sound,but in the conservatively rated components. The over-sized power transformer, the conservative operating levelsof the MOSFETs, the computer-grade electrolytics total-ling 40,000 microfarads, the enclosed relay, the use of filmcapacitors in s

17、ignal circuits-all are evidence of the designefforts to achieve exceptional reliability simultaneouslywith state of the art sonics and specifications. So rugged isthe DH-500 that it can deliver over 20 amperes into a shortcircuit!For those with special power needs, the DH-500 can beadapted to monoph

18、onic operation, delivering in excess of800 watts into 8 ohms, by installing the DH-502 inputbridging kit.Those who have chosen to build this amplifier from thekit will find the assembly instructions assume no technicalability other than how to make a good solder connection.Even that has been describ

19、ed for those who are new to thefun of kit building. Through pre-assembly and testing ofthe complete signal module, the performance of the kit hasalready been assured, for assembly involves little morethan interconnection of the power supply and control ele-ments. You can look forward to just a few h

20、ours of con-struction fun, to hear the finest audio amplifier yet pro-duced.CONTENTSinstallation.Page 4Operation.4Connections.5Assembly Instructions.6If Problems Arise .I4Circuit Description.I5Schematic Diagram.16Component Values.17AC Line Connections for Overseas Use .I8Kit Parts List.I9Service and

21、 Warranty.20Pictorial Diagram.Insert3INSTALLATIONThe DH-500 may be installed out of sight in many appli-cations, where its power can be controlled by the ACswitching of a preamplifier control unit. However, anyhigh power amplifier may draw enormous amounts of cur-rent, so you should make sure your p

22、reamplifier has theswitching capacity for the amplifier s needs, as well as anyother equipment which it also switches. inadequate switchcurrent capacity may eventually render the switch in-operativeThe power switches in Hafler preamplifiers have beenchosen for their high ratings, and have been teste

23、d anddeemed suitable for normal home switching of the DH-500. However, if the amplifier is intended for operation atsustained high power levels, or where power switching isvery frequent, or where the control unit must switch sub-stantial additional current for other equipment, or if yourcontrol unit

24、 does not have the 15 ampere switching capac-ity, you should use the power switch on the DH-500, andconnect it directly to the AC line. In such use, turn theamplifier on last, and switch it offfirst. This will avoid pos-sible loudspeaker damage from turn-on transients gener-ated by source equipment.

25、A power transformer of this size puts out a noticeablehum field, even though the special design of this trans-former minimizes such radiation. If the amplifier is to beinstalled close to a record player, you should first check forfreedom from hum pickup by the phono cartridge. Somecartridges are muc

26、h more sensitive than others, and re-quire more separation from the amplifier. Check at a rela-tively high volume setting, while swinging the tone armthroughout its arc. A few inches additional space will usu-ally solve any problem.Ventilation is most important! Unobstructed air circula-tion at the

27、sides and back is important for long trouble-freelife. A 3 speed fan operates at its lowest speed wheneverthe amplifier is turned on, and is automatically switched tohigher speeds at the power output demands it. Air is drawnin at the sides, and expelled to the rear. With normal homemusic levels the

28、cooling capacity is sufficient that the fanwill rarely operate at other than low speed, where it is soquiet that your ear must be close to a vent to hear it.The front panel is designed to facilitate mounting in astandard 19” rack. Be sure all of the cover screws are instal-led when the unit is suppo

29、rted by the front panelOPERATIONThe AC power cord should be plugged into a source of120 volts, 60 Hz, unless the amplifier is specially providedwith the multi-voltage optional transformer. Press thepower switch to the right to turn the amplifier on. A redpilot lamp in the power switch signifies that

30、 it is on. If it isnot illuminated, the most likely cause is a blown AC linefuse. That is the single fuse close to the switch inside thechassis. However, since the amplifier uses a 15 ampereslo-blo fuse, and the typical home circuit is also rated at 15amps, check that as well.To avoid the turn-on tr

31、ansients generated in many con-trol units, there is a 3 second delay before the relay con-nects the speakers. A few preamps may require a longerdelay to avoid their internally generated turn-on pulses.Information on extending this turn-on delay is availablefrom the company on request.A standard 2-wi

32、re power cord was chosen in preferenceto a 3-wire grounded AC cord, because there is no signific-ant current leakage in this design. Where local require-ments dictate the need for a 3-wire power connection, aground lug may be attached to the chassis adjacent to theAC line fuse holder.If the pilot la

33、mp should ever blink (about 2-3 times asecond), this signifies that a protective thermal breakerhas shut down the amplifier because ofexcessive heat sinktemperature. The fan will be operating at its highest speed,and as soon as the heat sink temperature has declined, theamplifier will automatically

34、return to normal operation.Such an occurrence is extremely unlikely, and if theamplifier shuts down again and the lamp flashes, youshould check for inadequate ventilation, or an excessiveinput signal, an extremely low load impedance, or an inputwhich may have dangerous signal content (such as osciIl

35、a-tion). Failing evidence of this, the fan or the amplifier mayhave malfunctioned, Because of the very effective fancooling, any normal signal will not cause the amplifier tooverheat.At normal home use levels, the average power con-sumption is likely around 250 watts. The unit s efficiencyis about 5

36、O%, so some full power tests may exceed the ca-pacity of a 15 amp circuit. When performing tests, voltagelosses due to long lines should be taken into consideration,or compensated for.Loudspeaker Fuse SelectionThe DH-500 is supplied with 2 ampere fuses in thespeaker lines. This conservative value ha

37、s been chosen forinitial use because most high quality speaker systems can-not safely handle very high power levels, even though ahigh power amplifier invariably makes them sound theirbest. Since a substantial overload must continue for a fewseconds before a fuse blows, a 2 ampere fuse will allowver

38、y high power peaks to pass without hindrance, yet willprotect most speaker systems. Smaller fuses tend to blowtoo easily, and it is unlikely you will be using speakers withlow power ratings with the DH-500. Larger fuse sizes maynot adequately protect the majority of speakers intendedfor home listeni

39、ng.If the manufacturer of your speakers recommends aspecific fuse value for their protection, you should obtain3AG type fuses of that value and substitute them for theones supplied. The speaker fuses are included in theamplifier design solely for speaker protection. They do notprotect, or affect, th

40、e amplifiers operation. A blownspeaker fuse does not indicate malfunction-simply ahigher than normal output signal. If the amplifier producesa low level distorted signal, a blown speaker fuse is themost likely cause.We do not recommend the use of a slo-blo type fuse forspeaker protection. If your sp

41、eakers can handle the higherpower levels safely, and you wish to install fuses of higherratings, we suggest-for the sake of the speakers-thatyou increase fuse size in l/2 ampere increments. THISAMPLIFIER IS ABLE TO DELIVER SUBSTAN-TIALLY MORE POWER THAN MOST SPEAKERSCAN SAFELY TOLERATE. Therefore th

42、e Hafler Com-pany cannot assume any responsibility for damage to theload (loudspeaker) because the choice o f fuse six is inyour hands .The 2 amp fuse, with an 8 ohm load, permits continuouspower up to 32 watts, with peaks well above that. 2-l/2amps passes 50 watts; 3 amps, 72 watts; 5 amps, 200 wat

43、ts.We have included a pair of 5 amp fuses as alternates, fortemporary use as spares; for testing the amplifier at veryhigh power levels; and for operation into very low load im-pedances, 5 amps will pass 80 watts into a 4 ohm load. Wesuggest that you obtain additional type 3AG fuses of theappropriat

44、e size for your speakers.Loudspeaker Power RatingsThere are no U.S. standards for rating the power han-dling capabilities of loudspeakers. As a result the manufac-turers usual “music power” ratings, or suggestedamplifier limits, are of only minimal help in determiningsafe operating levels with ampli

45、fiers which can deliverenormous amounts of power. On the other hand, somespeakers, particularly tweeters, can also be damagedthrough the use of too small an amplifier if it is driven intosustained clipping. However, tweeters are also more vul-nerable to high level signals which are not always notice

46、-ably loud to the ear (as from electronic music sources), soyou may wish to separately protect the tweeters with fusesof lower rating. You must take into consideration the typeof music, and the levels you like, to provide long termtrouble-free operation of your speaker choice, when youhave a very po

47、werful amplifier like the DH-500.If more than one pair of speakers will be connected tothe amplifier, proper protection would dictate that eachspeaker be separately fused, since when they are operatedin parallel, the combination of lower impedance and thehigher power handling capacity would suggest

48、a muchlarger fuse at the amplifier than would provide individualprotection.If full power tests are to be performed, particularly atlow load impedances, fuse ratings above 10 amps may berequired for the duration of the test.CONNECTIONSACThe standard unit is intended for 120 volt, 60 Hz opera-tion. If

49、 it is controlled by an AC switch on a preamplifier,the DH-500 power switch may be left on.If your line voltage is other than that provided in theUnited States, be sure you have the alternate multi-voltagepower transformer, and be sure it is wired for your mainsvoltage before you plug in the amplifi

50、er. The connectionsfor other line voltages will be found in the back of thismanual.InputStandard phono jacks are installed to accept conven-tional shielded cables, such as those supplied with yourpreamplifier. Be sure that the outer shield connection issecure, to avoid hum. The length of these cable