HHScott-208-pwr-sm 维修电路原理图.pdf

H.H.SCOTT-IIIPowdermillRoad, Maynard,Mass.INSTRUCTIONS FOR THE MODEL 20s SO-wattSTEREOPHONICLABORATORY POWER AMPLIFIERThe 208 is a precision, dual power amplifier designed for high quality audio appli-cations.It is ideally suited for use with the 355 AM-FM multiplexstereo control centeror a good quality preamplifier.The 208 is completely stable under all conditionsand maybe used with any electrostatic loudspeakers. .INSTALLATIONThe 208 can be placed on a shelf.in a cabinet, or in a bookcase.When used withthe 355 it may be as close or as far as desired.If you wish, the 208 may actually beclamped to the 355 to make an integrated unit.The two clamps for this purpose are avail-able at no charge by writing to the Parts Dept., H. H. Scott, III Powdermill Rd., Maynard,Mass.Wherever the 208 is placed, adequateprovision for ventilationshould be made . Neverenclose the amplifier completely.If it is placed inside a cabinet, either the back or thefront should have openings to allow dissipationof the warm air.CONNECTIONSTo the Model 355 - If you plan to use the 208 bolted to the 355, or next to it, theshort leads supplied with the 208 are ideal.Connect one cable from the 355 left output tothe left 1.5v input on the 208.Connect the other cable from the 355 right Output to theriht channel l.5v input on the 208.If you intend to separate the 208 fram the 355, useloner audio cables but follow the same connectioninstructions.To a Preamplifier - Shielded audio cables are provided with most preamplifiers.Ifyou are using preamplifiers with over 2.0 volts output connect shielded cable from thepreamplifiersLeft or Channel A output to the Left 2.5 volt input.on the 208.Connectanother cable from the Right or ChannelB output of the preamplifier to the right 2.5 voltinput on the 208.If you use a preamplifierwith 1.0 to 2.0 volt output, follow the samedirectionsexcept use the 1.5 voltinputs on the 208.Power Connections - The power cord60 cycle, AC source.Do not use with DC.liary AC outlets on the back of the 355 orner, leave the on-off switch of the 208 inpreamplifier)is turned on or off, it willshoul be plugged into any 105 to 125 volt, 50 toThe amplifier can be connected to any of the auxi-of your preamplifier.When connected in this man-the on position at all times.When the 355 (orturn the 208 on or off at the same time.Auxiliary AC outlets - The 208 has an auxiliary AC outlet.You may connect any unitslike a turntable or tape recorder to this outlet.When the 208 is turned off, these unitswill go off as well.Speakers - Terminal strips for makingspeaker connections are located on the back The one markedChannel A Speaker is for connecting the left speaker (as you face them).Theone markedChannel B Speaker is for the riht.Below each strip are the numbers 4, 8, 16 andO.This permits you to match the amplifier output to the impedance of the speaker.Eachspeaker is rated by its manufacturerat a certain impedance.This information is eithermarkedon the speaker or can be supplied by the dealer.D-208-1(ContinuedInside)RadioFans.CN 收音机爱 好者资料库To make the connections use standard twin lead lamp wire.Simply connect one end Jfthe twin lead wire to the two terminals on the speaker or speaker enclosure, as the case maybe.At the other end connect one lead to the0terminal and the other lead to the terminalwhose numberis closest to the value of the loudspeakerimpedance.When makingthe conne-tions, be extrenely careful to prevent any strands of wire fran one screw accidentallytoucn-ing a strand on the other screw, as the speaker will not perform properly.After the speakers are connected, they should be properly phased to ive a full stereeffect with good bass.The simplest way to accanplishthis is to feed the same monophonicpr-og ram mater ial simultaneously into both channels.Amale speaking voiceis ideal for thispurpose.Turn the volume to full roan level.Stand in front of the two speaker systems andmidwaybetween them.Have saneone reverse the leads of one speaker.In one position, thevoicewill sound full and appear to be caning fran directly between the two speakers.Inthe other position, the voice will lose some of its bass, and will appear to be coming fromboth speakers.The first is the correct position.SPECIFICATIONSMaximum power output each channel at-IOoo cycles:- Mus1c wave orms;: 40 wattsSteady state 35 watsMaximum total harmonic distortion at rated output 0.5%Frequency response for 35 watts steady state at less than 2.0%total distortion .20to 20,000 cyclestodb.Maximum usable power output at 20 cycles:Music waveforms !42 wattsSteady state 36 wattsPowerbandwidthatrateddistortion(IHFMmethod).below19 cyclesto*above 25,000 cycles(limits of test equip)Intermodulationdistortion.below 0.5%HlDTland noise. .,80 db.below ratedpower(These characteristicsare measuredat a line voltage of117volts rms and line frequency o60 cycles per second.No significant changes of characteristicsshould be experienced:ornormal variationsof line voltages or a line frequencyof50cycles per second).Range of line voltage and frequency 105-125volts,50-60 cyclest?owerconstLil-ptic-l-1:1.v-o.l+C!.:1+0 cpA-.L.-on.1Y)9.e- .-.O-C-;,T-c.-.:2QO.-Wa.:t.t.s*All H. H. Scott amplifiers and preamplifiersincorporate a low frequency rolloff which be-comes full operative below 20 cycles.This is designed to prevent overload of the outputstae and the loudspeaker due to subsonic rumble frequencies and record eccentricity.Thismeans that the full power of the amplifier can be concentrated into the audible range.RadioFans.CN 收音机爱 好者资料库GENERALSERVICENOTES1.Checl1IOOII1110c0.-I.901-0-e.n.220M.IMV(C-,!:Y2.0(C.,/00INOVTIII62T,:)1(III101I.VIIP-JTf!l:121(,2.tOvIi1_v1 1001111.70 VQIIJrJV=I=ao/ooT%00O/oO17/75+-v/V+-J/V-./vI-0(6.2.IsnI6n.r;:;.18!L 18n.IWYlwIWIW-.8L.EF=T C .t-JNELIiJoJ,1a.,Pa,-o-IYo-O-Fllro2S+.oo,:.0-0.ellWc.c. o.OUT.LTIA.!.pfRxlI,e. .1/.-Ie.VtD7591-rYPE;:.?:-:l:=.-=-,H:L:IILR.x-I-IIooooo.VOTINT.-(h,1.-=-ds n,4-1I1_-,xjRIGHTCHANN!.LtVOl.Tc;.f.&ML .auc:tLOWIT-!111-I Nt.uela.V.O.M.,.IN01GA.T&SM.TC,t04LO*tt.SlaTOq,.,-I. 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