Quad_405维修电路原理图.pdf

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1、 405 POWER AMPLIFIERPOWER AMPLIFIER Service DataService Data The Acoustical Manufacturing Co. Ltd. () Huntingdon, Cambridgeshire, PE29 6XU, England Tel: +44(0)1480 447700 Fax: +44(0)1480 431767 www.quad-hifi.co.uk RadioFans.CN 收音机爱 好者资料库 ContentsContents Circuit Description Test Equipment Disconnect

2、ing Clamp Circuits Amplifier Circuit Testing Clamp Circuit Testing Fault Finding Modifications Clamp Circuit Replacing a Clamp Board Conversion of a 405 to a Mono 180 watt amplifier Replacing Transformer Replacing Amplifier Modules 405-2 405-2 Assembly Diagram page 3 4 4 5 5 6 8 9 9 10 11 11 12 13 2

3、 Circuit Diagram M12333 iss. 2 - Amplifier PCB M12368 iss. 5 & 6?14 Circuit Diagram M12333 iss. 3 - Amplifier PCB M12368 iss. 7?15 Circuit Diagram M12333 iss. 4 - Amplifier PCB M12368 iss. 9?16 Circuit Diagram M12333 iss. 5 - Amplifier PCB M12368 iss. 9 & 10?17 Amplifier Board layout M12368 iss. 9 &

4、 10?18 Circuit Diagram M12333 iss. 6 - Amplifier PCB M12565 iss. 3?19 Amplifier Board layout M12565 iss. 3?20 Circuit Diagram M12333 iss. 7 - Amplifier PCB M12565 iss. 5? 21 Circuit Diagram M12333 iss. 8 - Amplifier PCB M12565 iss. 6?22 Circuit Diagram M12333 iss. 9 - Amplifier PCB M12565 iss. 7?23

5、Circuit Diagram M12333 iss. 10 - Amplifier PCB M12565 iss. 7?24 Keith Snook modifications Click here RadioFans.CN 收音机爱 好者资料库 CIRCUIT DESCRIPTIONCIRCUIT DESCRIPTION The QUAD 405 is two channel power amplifier primarily intended for use in high quality sound reproducing systems. The amplifier is usual

6、ly used with QUAD control units though other signal sources can readily be accommodated. amplifier uses current dumping output circuit, invention which eliminates many of problems associated with transistor amplifiers, and covered by patents in several countries. In current dumping amplifier there i

7、s in effect both a low powered very high quality amplifier and a high powered heavy duty amplifier. low power amplifier controls the loudspeakers at all times, calling upon the high power section to provide most of the muscle. The small amplifier is so arranged - it carries an error signal - that pr

8、ovided the larger power transistors (the dumpers) get within the target area of the required output current it will fill in the remainder accurately and completely. The reproduced quality is solely dependent on th small amplifier which because of its low power can be made very good indeed. Problems

9、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 less restrictive. Fig. 1 Simplified Schematic of QUAD 405 Amplifier showing Class A, Dumpers

10、 and Bridge Components. 3 RadioFans.CN 收音机爱 好者资料库 TEST EQUIPMENTTEST EQUIPMENT Sound Technology Distortion Analyser 1700A (ST1700A)Sound Technology Distortion Analyser 1700A (ST1700A) Dual Beam OscilloscopeDual Beam Oscilloscope 4 and 8 load of 100W dissipation4 and 8 load of 100W dissipation 1 load

11、 of 25W dissipation1 load of 25W dissipation 2.5 kHz Square Wave Generator2.5 kHz Square Wave Generator Input 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

12、 supply Variac a.c. power supplyVariac a.c. power supply Fig. 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 CIRCUITSDISCONNECTIN

13、G CLAMP CIRCUITS When 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

14、 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 access to printed copper side of amplifier boards. three screws securing each side panel should be removed, panel may thn b slid outwards from amplifier

15、. 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. 4 RadioFans.CN 收音机爱 好者资料库 AMPLIFIER CIRCUIT TESTING M12368 - M12565AMPLIFIER CIRCUIT TESTING M12368 - M12565 follow

16、ing 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/cm ST 17OOA-ST 17OOA- Volts/power 100W RMS Volts/power 100W RMS Distortion Ratio 0.01%Distortion Ratio 0.01%

17、8OkHz and 400 filters both in8OkHz and 400 filters both in Frequency 1Frequency 1 Low DistortionLow Distortion Osc. level minimumOsc. level minimum ConnectionsConnectionsLoad 8 Load 8 SlSl Sine Wave Sine Wave (STl7OOA)(STl7OOA) S2 Left InputS2 Left Input S3 Left OutputS3 Left Output If Amplifier fai

18、ls 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

19、 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 shou

20、ld be less than 0.01% Select volts/powervolts/power, decrease applied frequencyapplied frequency to 100Hz, remove 400Hz400Hz filter adjust osciIIoscope timebaseosciIIoscope timebase to 2ms/cm. Set level, select distortion which should be less than 0.01%. Select volts/powervolts/power, increase appli

21、ed frequencyapplied frequency to 3, select 400400 filter and adjust timebasetimebase to 50s/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. Adjust oscilla

22、tor 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. Reduce output leveloutput level to 80W. Set level and me

23、asure 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 and adjust timebasetimebase to 0.2ms/cm. following checks are to monitor low frequency roll off of 405. Select 3030

24、and output level should fall by approximately 0.3dB. Select 20Hz20Hz and output level should 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 limiting resistors into mini s

25、ockets on each amplifier board. For 405s with amplifier boards type M12565-3 insert a link into se sockets. output waveform should indicate clipping. Reduce oscillator level until clipping just disappears at which point output level should be 20V RMS 1V. Remove voltage voltage limitters, and adjust

26、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) but no overshoot. Reconnect

27、the 8 load. following checks should be carried out with no input signal and input to th amplifier board loaded by a 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 inp

28、ut 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 as 5 shown in Fig. 11. Select 4 load4 load, output level should be 70W just prior to clipping. CLAMP CIRCUIT TESTINGCLAMP CIRCUIT TE

29、STING ln order to test clamp circuit, circuit should first be disconnected from its amplifier board, s described 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

30、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. te

31、st 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. coupled Reproduced in pdf format by Keith Snook d.c.daylight ltd. 2002 RadioFa

32、ns.CN 收音机爱 好者资料库 FAULT FINDING FAULT FINDING 6 Reproduced in pdf format by Keith Snook d.c.daylight ltd. 2002 The 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 in

33、put should be a 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?CauseCause 1. R33 Burnt?Collector-Base Tr10 o/c R37 Burnt?L1 o/c (solder joints) R4

34、1 Burnt?L3 o/c (solder joints) R39 Burnt?R20 or R21 o/c R38 Burnt?D5 or D6 o/c 2. 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/c Draws high current which drops to 0.1A? after approx 2 seconds?R14 o/c 3. No increase in a.c. supply current for increase

35、 in signal?R3 o/c, C1 o/c, R31 o/c Signal is unstable and clips?R6 o/c 100W output for 0.3V input?R20 or R21 o/c Waveform trace as in Fig. 3?Tr8 o/c, Tr6 s/c, R36 o/c, R30 o/c, C10 s/c Waveform trace as in Fig. 4?L2 o/c (solder joints) Approximately 4W output?R16 o/c 4. Second Harmonic Distortion?IC

36、1, Tr1, Tr2, Tr3, Tr4, R5, R6, R17, R18, R22, C1 Second Harmonic Distortion especially at 100?C2, C7, C8 and on o/c load Third Harmonic Distortion especially at 100?R5 Third Harmonic Distortion?L2, R3, R6, R16, R20, R21, C3 Hum and Noise?C5 o/c Hum*?R37 o/c Waveform trace as in Fig. 5*?Tr3 s/c Wavef

37、orm trace as in Fig. 6*?R23 o/c, R5 o/c? Waveform trace as in Fig. 7?R33 s/c Waveform trace as in Fig. 8*?R8 o/c Waveform trace as in Fig. 9?C5 s/c, R15 o/c, Tr1 o/c 6. 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/c 10. Noise

38、especially at 100?R5 Noise with large spikes?Tr1 Noise?R12, R3, R4, Tr2, IC1 (change to topology!) 11. Current limiting check with 1 load Waveform trace as in Fig. 12?R29 o/c, R28 s/c, R25 o/c Waveform trace as in Fig. 13?D3 s/c, R27 o/c, R24 o/c, R26 s/c Waveform trace as in Fig. 14?Tr6 o/c Wavefor

39、m trace as in Fig. 8?C11 s/c Tr5 o/c 13. Draws high current with 6V d.c. supply?T2 s/c RadioFans.CN 收音机爱 好者资料库 7 RadioFans.CN 收音机爱 好者资料库 MODIFICATIONS TO PRINTED CIRCUIT BOARDS.MODIFICATIONS TO PRINTED CIRCUIT BOARDS. ?Amplifier Board M12368 iss.5Amplifier Board M12368 iss.5 originally fitted. ?Circ

40、uit 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.7Amplifier board M12368 iss.7 ? ? ? ?Circuit diagram iss. 3. ?R4 changed from 10k to 22k ?R5 changed from 10k to 4k7 ?R9 changed fr

41、om 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)?A

42、mplifier 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

43、 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 ser

44、ial 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 LR15

45、0C (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.? ?

46、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 link 6.?Amplifier board M12565 iss.5Amplifier board M12565 iss.5 ( 405-2 PCB). ?Circuit diagram iss. 7. ?Was fitted at

47、 serial number 62500 but with a 405 name plate until serial number 65000. ?See page 12 for 405-2 PCB changes. AlternativesAlternatives Transistors - 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 transistor

48、s may cause instabiliity. On M12368 iss. 9 &10 and M12565 iss. 3 Transistors Tr9 and Tr10 may be 2SD424, 17556 or 2SD676 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 interch

49、angeable. LED - LP1 - HP5082-4850, Exciton XC5053, Toshiba TLR114A (or any modern LED with R40 adjusted). 8 RadioFans.CN 收音机爱 好者资料库 Fig. 15 1.? 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 ov