Quad-405-pwr-sm1 维修电路原理图.pdf
405POWER AMPLIFIERPOWER AMPLIFIERService DataService Data The Acoustical Manufacturing Co. Ltd. () Huntingdon, Cambridgeshire, PE29 6XU, England Tel: +44(0)1480 447700 Fax: +44(0)1480 431767www.quad-hifi.co.ukRadioFans.CN 收音机爱 好者资料库ContentsContentsCircuit DescriptionTest EquipmentDisconnecting Clamp CircuitsAmplifier Circuit TestingClamp Circuit TestingFault FindingModificationsClamp CircuitReplacing a Clamp BoardConversion of a 405 to a Mono 180 watt amplifierReplacing TransformerReplacing Amplifier Modules 405-2 405-2Assembly Diagram page34455689910111112132Circuit Diagram M12333 iss. 2 - Amplifier PCB M12368 iss. 5 & 6?14Circuit Diagram M12333 iss. 3 - Amplifier PCB M12368 iss. 7?15Circuit Diagram M12333 iss. 4 - Amplifier PCB M12368 iss. 9?16Circuit Diagram M12333 iss. 5 - Amplifier PCB M12368 iss. 9 & 10?17Amplifier Board layout M12368 iss. 9 & 10?18Circuit Diagram M12333 iss. 6 - Amplifier PCB M12565 iss. 3?19Amplifier Board layout M12565 iss. 3?20Circuit Diagram M12333 iss. 7 - Amplifier PCB M12565 iss. 5? 21Circuit Diagram M12333 iss. 8 - Amplifier PCB M12565 iss. 6?22Circuit Diagram M12333 iss. 9 - Amplifier PCB M12565 iss. 7?23Circuit Diagram M12333 iss. 10 - Amplifier PCB M12565 iss. 7?24Keith Snook modifications Click hereRadioFans.CN 收音机爱 好者资料库CIRCUIT DESCRIPTIONCIRCUIT DESCRIPTIONThe QUAD 405 is two channel power amplifier primarily intended for use in high quality sound reproducingsystems. The amplifier is usually used with QUAD control units though other signal sources can readily beaccommodated. amplifier uses current dumping output circuit, invention which eliminates many of problemsassociated with transistor amplifiers, and covered by patents in several countries.In current dumping amplifier there is in effect both a low powered very high quality amplifier and a high poweredheavy duty amplifier. low power amplifier controls the loudspeakers at all times, calling upon the high powersection to provide most of the muscle. The small amplifier is so arranged - it carries an error signal - that providedthe larger power transistors (the dumpers) get within the target area of the required output current it will fill in theremainder accurately and completely. The reproduced quality is solely dependent on th small amplifier whichbecause of its low power can be made very good indeed.Problems of crossover, crossover distortion, quiescent current adjustment, thermal tracking, transistor matching,all disappear. re are no internal adjustments or alignments and th choice of power transistor types is lessrestrictive.Fig. 1 Simplified Schematic of QUAD 405 Amplifier showing Class A, Dumpers and Bridge Components. 3 TEST EQUIPMENTTEST EQUIPMENTSound Technology Distortion Analyser 1700A (ST1700A)Sound Technology Distortion Analyser 1700A (ST1700A)Dual Beam OscilloscopeDual Beam Oscilloscope4 and 8 load of 100W dissipation4 and 8 load of 100W dissipation1 load of 25W dissipation1 load of 25W dissipation2.5 kHz Square Wave Generator2.5 kHz Square Wave GeneratorInput Sensitivity Indicator (0 to 1V RMS) Input Sensitivity Indicator (0 to 1V RMS) AVOmeter (or similar multitester)AVOmeter (or similar multitester) 0 to 12V d.c. power supply0 to 12V d.c. power supplyVariac a.c. power supplyVariac a.c. power supplyFig. 2 illustrates a simple switching circuit which may assist if much testing is anticipated.SUGGESTED SWITCHING ARRANGEMENT FOR TESTING QUAD 405 Fig. 2 Before testing, cover of 405 should be removed.DISCONNECTING CLAMP CIRCUITSDISCONNECTING CLAMP CIRCUITSWhen servicing 405 fitted with a clamp circuit, it may be necessary to bypass this circuit. For 405s fitted with amplifier boards M12368, this may be done by removing t push-on connectors carrying brown wires from amplifier boards, and connecting loads between black output terminals and output terminals on amplifier boards. For 405s fitted with amplifier boards type M12565, it will be necessary to remove th side panels to gain accessto printed copper side of amplifier boards. three screws securing each side panel should be removed, panel may thn b slid outwards from amplifier. If solder is removed from link pad shown in Fig.18(A), clamp circuit will become disconnected.Care should be taken to ensure that when testing is completed, link pad is r-soldered.4AMPLIFIER CIRCUIT TESTING M12368 - M12565AMPLIFIER CIRCUIT TESTING M12368 - M12565 following test procedure is with reference to a 240V amplifier with no voltage limiters. Select:ControlsControls Y1 - 0.5V/cm d.c. coupledY1 - 0.5V/cm d.c. coupled Timebas 0.2 ms/cmTimebas 0.2 ms/cmST 17OOA-ST 17OOA- Volts/power 100W RMS Volts/power 100W RMS Distortion Ratio 0.01%Distortion Ratio 0.01%8OkHz and 400 filters both in8OkHz and 400 filters both inFrequency 1Frequency 1Low DistortionLow DistortionOsc. level minimumOsc. level minimumConnectionsConnectionsLoad 8 Load 8 SlSl Sine Wave Sine Wave (STl7OOA)(STl7OOA)S2 Left InputS2 Left InputS3 Left OutputS3 Left OutputIf Amplifier fails any of t following tests, refer to appropriate prt of fault finding section, page 6.2.3.4.5.6.7.8.9.10.11.12.13.Check inside amplifier for obvious faults such as burnt components, blown internal fuses etc. Each of following checks should be repeated on t or channel.Apply a.c. Supply Voltsa.c. Supply Volts whilst observing current consumption which should not exceed 0.12A.Increase th oscillator leveloscillator level to 0.5V RMS 0.5. output should be 100W with no sign of clipping. Select set levelset level adjust meter deflection for zero. Select distortiondistortion which should be less than 0.01%Select volts/powervolts/power, decrease applied frequencyapplied frequency to 100Hz, remove 400Hz400Hz filter adjustosciIIoscope timebaseosciIIoscope timebase to 2ms/cm. Set level, select distortion which should be less than 0.01%. Select volts/powervolts/power, increase applied frequencyapplied frequency to 3, select 400400 filter and adjust timebasetimebase to50s/cm. Select distortiondistortion which should again be less than 0.01%.Select volts/powervolts/power, increase applied frequencyapplied frequency to 10kHz and adjust timebasetimebase to 20s/cm. Adjustoscillator leveloscillator level so that output is 100W. Set level n select distortiondistortion which should be less than 0.05%.Select volts/powervolts/power, increase applied frequencyapplied frequency to 20k and adjust timebasetimebase to 10s/cm. Reduceoutput leveloutput level to 80W. Set level and measure distortiondistortion which should be less than 0.1%.Select volts/powervolts/power and decrease frequency to 1kHz. Adjust oscillator leveloscillator level so that output is 100W andadjust timebasetimebase to 0.2ms/cm. following checks are to monitor low frequency roll off of 405.Select 3030 and output level should fall by approximately 0.3dB. Select 20Hz20Hz and output levelshould fall by approximately 1. Select 1010 and output level should fall by 7dB 1.5dB. Increase frequencyfrequency to 1. For 405s with amplifier boards type M12368 insert 1.8k voltage limitingresistors into mini sockets on each amplifier board. For 405s with amplifier boards type M12565-3insert a link into se sockets. output waveform should indicate clipping. Reduce oscillator leveluntil clipping just disappears at which point output level should be 20V RMS 1V. Remove voltage voltage limitters, and adjust oscillator leveloscillator level for 100W output. Select volts/powervolts/power square wavesquare wave input, (S1). Adjust timebasetimebase to 0.1ms/cm. Remove loadload and note difference in waveform with load and no load. re should be a slight difference in gain (10mV) butno overshoot. Reconnect the 8 load. following checks should be carried out with no input signal and input to th amplifier board loaded bya 1k resistor, (S1). Remove 400Hz400Hz filter and select noisenoise which should b better than -93 unweighted. Select volts/powervolts/power, 400Hz400Hz filter and sine wavesine wave input at frequencyfrequency of 1 and adjust oscillatoroscillator levellevel for 100W output. Select 1 load1 load. output should clip equally on both halves of th waveform as5shown in Fig. 11.Select 4 load4 load, output level should be 70W just prior to clipping. CLAMP CIRCUIT TESTINGCLAMP CIRCUIT TESTING ln order to test clamp circuit, circuit should first be disconnected from its amplifier board, sdescribed on page 4.For 405s fitted with amplifier boards M12368 apply 6V d.c.6V d.c. across output terminals of relevant channel with an ammeter in circuit.For 405s fitted with amplifier boards M12565 wire should be soldered across back of amplifer board as shown in Fig. 18(B). 6V d.c. should be applied between this wire and black output terminal of relevant channel, with an ammeter in circuit.In both cases current should not exceed 0.5mA. Reverse th polarity of supply and repeat test. test should n be carried out on or channel. T complete test should thn be repeated using a 12V d.c. supply with a 10 resistor in series, when current should be approximately 1A. 1.Y2 - 0.1V/cm d.c. coupledY2 - 0.1V/cm d.c. coupledReproduced in pdf formatby Keith Snookd.c.daylight ltd. 2002FAULT FINDING FAULT FINDING 6Reproduced in pdf formatby Keith Snookd.c.daylight ltd. 2002The following information may assist in locating faults occuring on the amplifier boards of a 405.In each case only the faulty channel of the 405 is driven, as in the test procedure. The input should bea sine wave of 0.5V RMS and the output should be applied to an 8 load unless otherwise stated.The numbers refer to the relavent test check.*Board type M12368 only *Board type M12565 only.EffectEffect?CauseCause1.R33 Burnt?Collector-Base Tr10 o/cR37 Burnt?L1 o/c (solder joints)R41 Burnt?L3 o/c (solder joints)R39 Burnt?R20 or R21 o/cR38 Burnt?D5 or D6 o/c2.High Current?Tr2 o/c, Tr3 o/c, Tr7 o/c Tr9 s/c?Tr10 s/c, R7 o/c C8 s/c*?C3 s/c*?D2 o/c R8 o/cDraws high current which drops to 0.1A?after approx 2 seconds?R14 o/c3.No increase in a.c. supply currentfor increase in signal?R3 o/c, C1 o/c, R31 o/cSignal is unstable and clips?R6 o/c100W output for 0.3V input?R20 or R21 o/cWaveform trace as in Fig. 3?Tr8 o/c, Tr6 s/c, R36 o/c, R30 o/c, C10 s/cWaveform trace as in Fig. 4?L2 o/c (solder joints)Approximately 4W output?R16 o/c4.Second Harmonic Distortion?IC1, Tr1, Tr2, Tr3, Tr4, R5, R6, R17, R18, R22, C1Second Harmonic Distortion especially at 100?C2, C7, C8and on o/c loadThird Harmonic Distortion especially at 100?R5Third Harmonic Distortion?L2, R3, R6, R16, R20, R21, C3Hum and Noise?C5 o/c Hum*?R37 o/cWaveform trace as in Fig. 5*?Tr3 s/cWaveform trace as in Fig. 6*?R23 o/c, R5 o/c?Waveform trace as in Fig. 7?R33 s/cWaveform trace as in Fig. 8*?R8 o/cWaveform trace as in Fig. 9?C5 s/c, R15 o/c, Tr1 o/c6.Distortion at 20?D5 or D6 s/c,8.Liimiting resistor R11 has no effect?R10 s/c 9.Square Wave trace as in Fig. 10?C6 o/c10.Noise especially at 100?R5Noise with large spikes?Tr1Noise?R12, R3, R4, Tr2, IC1 (change to topology!)11.Current limiting check with 1 loadWaveform trace as in Fig. 12?R29 o/c, R28 s/c, R25 o/cWaveform trace as in Fig. 13?D3 s/c, R27 o/c, R24 o/c, R26 s/cWaveform trace as in Fig. 14?Tr6 o/cWaveform trace as in Fig. 8?C11 s/c Tr5 o/c13.Draws high current with 6V d.c. supply?T2 s/c 7MODIFICATIONS TO PRINTED CIRCUIT BOARDS.MODIFICATIONS TO PRINTED CIRCUIT BOARDS.?Amplifier Board M12368 iss.5Amplifier Board M12368 iss.5 originally fitted. ?Circuit diagram iss. 2.1.?Amplifier board M12368 iss.6Amplifier board M12368 iss.6?Copper track layout modified - component layout nchanged.2.?Amplifier board M12368 iss.7 ? ?Amplifier board M12368 iss.7 ? ?Circuit diagram iss. 3.?R4 changed from 10k to 22k?R5 changed from 10k to 4k7?R9 changed from 180 to 220?R19 (3k3) removed (combined with R23)?R23 changed from 3k3 to 1k2?C9 (330pF) removed (would be in parallel with C11)?C18 47nF fitted to -ve supply after FS2 - see circuit diagram?FS1 and FS2 effectively changed places?R2 changed from 2.2 to 10?Copper track width reduced?3.(a)?Amplifier board M12368 iss.9 Amplifier board M12368 iss.9 introduced serial number 9000.? Circuit diagram iss. 4.?R41 22 added?L3 6.9H added?C15 0.1F added?C16 0.1F added?C18 (47nF) removed?C19 1nF fitted between base and collector of Tr10 (not recommended if stable without)?Copper track width reduced?Also at s/n 9000 a clamp circuit, on PCB M12400, was mounted on the output terminal (Fig. 15).?This detects excessive d.c. offset at the output and short circuits, blowing the internal 4A fuses?FS1 and/or FS2 to protect the loudspeaker.3.(b)?The following component changes were made serial number 29000.?Circuit diagram iss. 5.?R10 changed from 1k to 1k8?R27 changed from 8k2 to 15k?R29 changed from 8k2 to 15k?R35 changed from 0.08 to 0.091?R36 changed from 0.08 to 0.091?D1 changed from LR120C to LR150C (op-amp voltage increased from 12V to 15V)?D2 changed from LR120C to LR150C (op-amp voltage increased from 12V to 15V)4.?Amplifier board M12368 iss.10Amplifier board M12368 iss.10?Identical to M12368 iss. 9 except copper pads for power transistors modified for production.5.?Amplifier board M12565 iss.3 Amplifier board M12565 iss.3 Introduced at serial number 59001.? ?Circuit diagram iss. 6.?Other QUAD 405s with this PCB fitted were serial numbers 57301 to 57600 inc.?This board incorporates the clamp circuit and the ESL voltage limiter is now a link6.?Amplifier board M12565 iss.5Amplifier board M12565 iss.5 ( 405-2 PCB). ?Circuit diagram iss. 7.?Was fitted at serial number 62500 but with a 405 name plate until serial number 65000.?See page 12 for 405-2 PCB changes.AlternativesAlternativesTransistors - on PCB M12368 iss. 5, 6 & 7 BDY77 or BDY74 may have been used for Tr9 and Tr10.BDY77 is a suitable replacement for both but beware - faster transistors may cause instabiliity.On M12368 iss. 9 &10 and M12565 iss. 3 Transistors Tr9 and Tr10 may be 2SD424, 17556 or2SD676 and are interchangeable.Tr2 - BC682, ZTX304, BCX32 and BC546B are interchangeable.Tr3, Tr4 - E5458, ZTX504 and BC556B are interchangeable.Tr7, Tr8 - 40872 or 2SA740 are interchangeable.LED - LP1 - HP5082-4850, Exciton XC5053, Toshiba TLR114A (or any modern LED with R40 adjusted).8Fig. 151.? Disconnect the wiring to th right channel circuit board and fold it back onto the transformer. Loosen the?clamp holding the electrolytic capacitor next to the output terminals, and lift capacitor out of the way.2,? Disconnect leads to the output sockets, place the clamp board over the output connectors and re-solder.?It is advisable to tin the output connector tags before positioning clamp board. This makes soldering easier.?Replace the capacitor and reconnect the tags to th right channel amplifier board.CLAMP CIRCUIT ALTERNATIVEST1 - 2N4992 or BS08A-03T2 - Sc141B or TIC226B or RCA T2800VOLTAGE SELECTORSOLDER BOARD & WIRESTO OUTPUT SOCKETSOUTPUT SOCKETSINPUT SOCKET9CLAMP CIRCUITCLAMP CIRCUITIntroduced co-incident with amplifier PCB M12368 iss. 9 serial number 9001. All 405s with serial numbers 9000 under being returned for service,
