FidelityRadio-20_20A-int-维修说明书手册含电器原理图

FIDELITY RADIOService Card20-20AHIGH QUALITYSTEREOAMPLIFIERThe 20-20A is a solidstate stereo amplifier designed toPHONO:input from magnetic pickup,pins 3(LH)andDIN 45-500 standards and incorporating 47 semiconductor5 (RH).-3mV into 50k.Input from ceramic pickup,pinsdevices.The LH and RH amplifier channels each employ 171 (LH)and 4 (RH).-70mV into 50ktransistors and one IC.Four diodes are used as a bridgeTAPE:accepts input from tape recorder (pins 3,5)andrectifier.Five further diodes are used to stabilise supplysupplies output to tape recorder amplifier (pins 1,4).points.Two transistors are used in an electronic protectionInput-250mV into 25k.circuit to protect the amplifier against accidental shortAUX:auxiliary input,pins 3(LH)and 5(RH),250mVcircuits.into 25m2.QUAD:Insertion of plug disconnects the preamplifierfrom the power amplifier,simultaneously providing aInputsconnection to each of the ouputs from the preamplifier andFive 5-pin DIN sockets are provided at the rear toto each of the inputs to the power amplifier.The twoaccept the following inputs:outputs(pin 1 LH,pin 4 RH)may be fed to a quadraphonicspecificationCrosstalk50dB at 1kHzOutput Power40dB at 250Hz to 10kHz20W per channel sinewave,into 830W per channel speech/Music power,into 80.Scratch Filter-3dB at 6kHz (12dB/octave filter).Harmonic DistortionLess than 0-2%overall,at 20WLess than 0.1%power amplifier only,at 20WRumble Filter-3dB at 100Hz(10dB/octave filter).Frequency Response20Hz to 26kHz -2dBContour30Hzto16kHz士1dB+16dB at 50Hz.+9dB at 10kHzSignal-to-Noise RatioTone ControlsMagnetic input,65dBBass:+16dB-18dB at 50HzOther inputs,70dBTreble:+16dB -15dB at 10kHzFIDELITY RADIO LTDService Department:2 CHASE ROADL0ND0NNW106 HZ TEL:01-9659235/6