HHScott-208-pwr-sm 电路图 维修手册.pdf

H.H.SCOTT- IIIPowdermillRoad, Maynard,Mass. INSTRUCTIONS FOR THE MODEL 20s SO-watt STEREOPHONICLABORATORY POWER AMPLIFIER The 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 center or a good quality preamplifier.The 208 is completely stable under all conditionsand may be used with any electrostatic loudspeakers. . INSTALLATION The 208 can be placed on a shelf.in a cabinet, or in a bookcase.When used with the 355 it may be as close or as far as desired.If you wish, the 208 may actually be clamped 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 . Never enclose the amplifier completely.If it is placed inside a cabinet, either the back or the front should have openings to allow dissipationof the warm air. CONNECTIONS To the Model 355 - If you plan to use the 208 bolted to the 355, or next to it, the short leads supplied with the 208 are ideal.Connect one cable from the 355 left output to the left 1.5v input on the 208.Connect the other cable from the 355 right Output to the riht channel l.5v input on the 208.If you intend to separate the 208 fram the 355, use loner audio cables but follow the same connectioninstructions. To a Preamplifier - Shielded audio cables are provided with most preamplifiers.If you are using preamplifiers with over 2.0 volts output connect shielded cable from the preamplifiersLeft or Channel A output to the Left 2.5 volt input.on the 208.Connect another cable from the Right or ChannelB output of the preamplifier to the right 2.5 volt input on the 208.If you use a preamplifierwith 1.0 to 2.0 volt output, follow the same directionsexcept use the 1.5 voltinputs on the 208. Power Connections - The power cord 60 cycle, AC source.Do not use with DC. liary AC outlets on the back of the 355 or ner, leave the on-off switch of the 208 in preamplifier)is turned on or off, it will shoul be plugged into any 105 to 125 volt, 50 to The 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 (or turn the 208 on or off at the same time. Auxiliary AC outlets - The 208 has an auxiliary AC outlet.You may connect any units like a turntable or tape recorder to this outlet.When the 208 is turned off, these units will 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).The one markedChannel B Speaker is for the riht.Below each strip are the numbers 4, 8, 16 and O.This permits you to match the amplifier output to the impedance of the speaker.Each speaker is rated by its manufacturerat a certain impedance.This information is either markedon 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 Jf the twin lead wire to the two terminals on the speaker or speaker enclosure, as the case may be.At the other end connect one lead to the0terminal and the other lead to the terminal whose 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 stere effect with good bass.The simplest way to accanplishthis is to feed the same monophonic pr-og ram mater ial simultaneously into both channels.Amale speaking voiceis ideal for this purpose.Turn the volume to full roan level.Stand in front of the two speaker systems and midwaybetween them.Have saneone reverse the leads of one speaker.In one position, the voicewill sound full and appear to be caning fran directly between the two speakers.In the other position, the voice will lose some of its bass, and will appear to be coming from both speakers.The first is the correct position. SPECIFICATIONS Maximum power output each channel at-IOoo cycles:- Mus1c wave orms;: 40 watts Steady state 35 wats Maximum 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 cycles todb. Maximum usable power output at 20 cycles:Music waveforms !42 watts Steady state 36 watts Powerbandwidthatrateddistortion(IHFMmethod).below19 cyclesto* above 25,000 cycles (limits of test equip) Intermodulationdistortion.below 0.5% HlDTland noise. .,80 db.below rated power (These characteristicsare measuredat a line voltage of117volts rms and line frequency o 60 cycles per second.No significant changes of characteristicsshould be experienced:or normal variationsof line voltages or a line frequencyof50cycles per second). Range of line voltage and frequency 105-125volts, 50-60 cycles t?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 output stae and the loudspeaker due to subsonic rumble frequencies and record eccentricity.This means 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 GENERALSERVICENOTES 1.Checl< 1 IOO II 1 11 0 c 0 .-I .901 -0- e.n. 220M. .I MV(C- ,!:Y 2.0(C.,/00 INOVTIII 62T ,:)1(III 101 I.V IIP-JT f!l:121(, 2.tOvIi1_v1 1001 111.70 V QI I JrJV=I= ao/ooT%00O/oO 1 7/75 +-v/V+-J/V-./vI-0( 6.2.IsnI6n.r;:;.18!L 18n. IWYlwIWIW -.8 L.EF=T C .t-JNELI iJ oJ <,1 a.,P a,-o-IYo-O - Fll r o2S +.oo,:.0- 0.ellW c.c. o. OUT.LT IA .!.p fRxl I,e. . 1/. -Ie. VtD 7591 -rYPE;:.?:-:l:=.-=-,H:L:IILR. x-I-II o o o o o .VOT INT. -(h,1. -=-ds n, 4- <1I1_-, x jRIGHTCHANN!.Lt VOl.Tc;.f.:.:;,:;:.:-.:.:.:.I.;.:.:.C:.:._.:MO,MSSUSA. Owo- , ,_,.,. ,j:-.:.iiN.-.,?e CII 5U8a