QSC-PLXseries-pwr-sm 维修电路原理图.pdf

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1、Technical Service ManualPLX SeriesLLLLLPLX 1202LLLLLPLX 1602LLLLLPLX 2402LLLLLPLX 3002TD-000078-00TD-000078-00RadioFans.CN 收音机爱 好者资料库+ PLX 1202+ PLX 1602+ PLX 2402+ PLX 3002RadioFans.CN 收音机爱 好者资料库PLX SERIESSERVICE MANUALPLX 1202PLX 1602PLX 2402PLX 3002QSC Technical ServicesWats: I -%OO-772-2034Local

2、: 1-714-957-7150Fax: 1-714-754-6173QSC Technical Support BBSI -714-668-75671-800-856-6003QSC Audio Products, Inc.1675 MacArthur Blvd.Costa Mesa, CA 92626http:/Table of ContentsPLX Product Specifications .Introduction .Test and Calibration .Troubleshooting PLX .PLX Parts List.PLX Semiconductors .Chas

3、sis Drawings .Schematics.PLX Series PCB Circut Board Drawings .12313PLX 1202 PCB Assembly (120V)23PLX 1202 PCB Assembly (230V)25PLX 1202 Chassis Assembly (120V)28PLX 1202 Chassis Assembly (230V)28PLX 1602 PCB Assembly (120V)28PLX 1602 PCB Assembly (230V)31PLX 1602 Chassis Assembly (120V)34PLX 1602 C

4、hassis Assembly (230V)34PLX 2402 PCB Assembly (120V)35PLX 2402 PCB Assembly (230V)38PLX 2402 Chassis Assembly (120V)41PLX 2402 Chassis Assembly (230V)41PLX 3002 PCB Assembly (120V)42PLX 3002 PCB Assembly (230V)45PLX 3002 Chassis Assembly (120V)48PLX 3002 Chassis Assembly (230V)495053PLX 1202 Main PC

5、B Schematics57PLX 1602 Main PCB Schematics62PLX 2402 Main PCB Schematics67PLX 3002 Main PCB Schematics7273PLX Product SpecificationsPLX 1202PLX 1602PLX 2402PLX 3002PLXI 202PLXI 602PLX2402 PLX3002Output Power (per channel):Continuous Average Output Power both channels driven:8ohms,2OHz-2OkHz,0.03%THD

6、 200 watts4ohms,2OHz-2OkHz,0.05%THD 325wattsCon0nuous Average Output Power bridged mono ooeration:300waKs 425 watts 550 watts500watts 700watts 900 watts8 ohms, 2OHz - 2OkHz, 0.1% THDVoltage Gain (dB)Sensitivity (for rated power 8 ohms)DistortionFrequency Response (LF Switched Off)Damping Factor (1 k

7、Hz and Below)NoiseInput ImpedanceDimensionsFaceplate WidthFaceplate HeightChassis DepthWeightNet, Lbs/kg700 iatts 1100 watts 1500 watts32 32 321.00vrms 1.20 Vrms 1.50 VrmsSMPTE-IM Less than 0.01%2OHz to 2OkHz, +I-0.2dB8Hz to 5OkHz, +Ol-3dBGreater than500106dB below rated output (20 Hz to 20 kHz)6k u

8、nbalanced, 12k balanced2000 watts321.70 vrmsStandard 19” Rack Mounting3.Y3.r13.2Y13.2v2119.5 2119.53.5” 3.Y13.2Y13.2Y2119.5 2119.5IntroductionThis manual is prepared to assist service personnel with the repair and calibration of PLX poweramplifiers . The procedures described in this manual require a

9、dvanced technical experienceand sophisticated audio test equipment.CAUTION: To reduce the risk of electric shock,do not remove the cover. No user-serviceableparts inside. Refer servicing to qualifiedpersonnel.CAUTIONWARNING: To prevent fire or electric shock, donot expose this equipment to rain or m

10、oisture.DocumentationThis manual contains schematics, printed circuit board (PCB) drawings, parts lists, andmechanical assembly drawings. This information should be used in conjunction with thetest and troubleshooting guide.The electrical and electronic components are identified by circuit identific

11、ation numbers onthe schematics and the parts list. The test & troubleshooting sections refer todesignations shown in the schematics.Equivalent PartsAlthough many of the electronic components used in this product may be available fromelectronic suppliers, some components are specially tested and appr

12、oved by WC. Aproduct repaired with non-WC supplied components may not meet factory specifications.Repairs performed using non-QSC parts may void the product warranty. men in doubt,you may contact QSC Technical Services for assistance.Parts orders to QSC should include the product model number, the p

13、art description, andthe QSC part number (from the parts list in this manual). Parts will be shipped via UPS,F.O.B. Costa Mesa, California. Shipping, handling and COD charges may be added tothe cost of the parts.Factory RepairIt may become necessary to return a product to the factory for repair. Call

14、 QSC TechnicalServices for return instructions. QSC Technical Services may be reached at (800)772-2834.Test and Troubleshooting Equipment- Distortion Analyzer capable of 0.01% THD+N- High Power Load Bank (8,4,8 2 ohms)- Function Generator 8 Digital Multimeter- 2OMHz Oscilloscope- Variac (0-140 VAC,

15、30-40A)-Audio Precision - System One+ Thermometer2T e s t & C a l i b r a t i o nPLX 1202 Test Procedure. SET-UP1. Connect a test load to the output terminals of the amplifier.2. Make sure Mode Switches 1 - 10 are in the default position (1 on, 10 on, all others off).3. Connect a distortion analyzer

16、 with a resolution of O.Ol%, 20-2OkHz (or better) to theoutput terminals of the amplifier. Enable the 8OkHz low pass filter.4. Connect a dual-channel oscilloscope to the following test points:Chl - a IOX (vertical sensitivity - 2V/cm) scope probe to the channel speaker output.Ch2 - a IX scope probe

17、(vertical sensitivity - O.lV/cm) to the distortion analyzeroutput.5. Set amp gain pots fully clockwise and turn on power switch.6. Connect the output of the signal generator to the input terminals of the amplifier andselect an output of 1.30 VRMS, 1 kHz sine wave.7. Plug the amplifier into a variac

18、and set up an AC line current monitor. POWER UP 8 MUTE DELAY TESTCAUTION: To avoid damage to the main printed circuit board, place a 50 ohm 225W resistor (100 ohm,240VAC) in series with the high (+) lead on the AC cable during variac ramp up. If the switching powersupply has a shorted device at init

19、ial power up, this AC resistor pad will help prevent undue damage. Afterthe amplifier has been fully powered up via the variac, confirm that the amplifier has achievedstable operation during idle. Remove AC power from the amplifier and disconnect the seriesresistor for normal operation. Continue wit

20、h the test & calibration process.I. Slowly raise the variac voltage and watch for excessive current draw (line currentgreater than 0.5A a.c. at 60 Volts). This is slightly less for 240V.Pause at 9OVAC(2OOVAC European) for three seconds until the mute I protect circuit disengages.Continue to 12OVAC (

21、240V European).2. Verify that the fan is operating at low speed.3. Turn the power switch off and on a few times to verify the 3 second power-up mutingdelay.l CHANNEL OUTPUTI. Look for amplified signal on the scope for channel 1. Switch the input signal and scopeto channel 2 and repeat output test. C

22、heck for noisy / contaminated gain pots byobserving general instability on the distortion waveform while adjusting the gain controllevels.2. Select an 8 ohm load and confirm that this amplifier is producing 200 watts at 1 kHz justbelow the point of clipping. Check both channels.l BRIDGE MODE1. Turn

23、the power switch off.2. Set Mode Switch #7 in the on position. The gain control, limiter, and filter switch positionson CH2 are disabled with Mode Switch #7 on.3. Set load to both red output binding posts (CHI positive and CH2 negative).4. Apply a 1.30 VRMS, 1 kHz sinewave input to channel I of the

24、amplifier. Check the powerand verify that the output does not immediately collapse. Check for 700 watts at 8 ohms.5. Turn power off and place the amplifier back into the Stereo mode with outputloads connected to each channel. BIAS1. Let the amplifier cool down to room temperature.2. With an input am

25、plitude of 1.3OVrms increase the input frequency to 2OkHz. Reduce theinput signal 20dB (80%) from full output. Adjust the crossover trimpot VR43 (CHl) andVR166 (CH2) for about a 4OOmVpk-pk crossover spike protruding from the noise traceon the oscilloscope. It will be necessary to have the oscillosco

26、pe measure unfiltereddistortion from the amplifier in order to see the crossover spike. It is necessary todisable the 80kHz lowpass filter on the analyzer for this test. Further trim so thatthe total distortion for that channel is less than 0.1% THD+N.3. With the trim settings achieved, and with no

27、signal plugged into the amplifier and with an8 ohm load, verify that the AC idle current from the AC service is no more than 1 .Oamperes.4. Let the amplifier cool down and check channel 2. SHORT CIRCUIT CURRENT1. Select a 2 ohm load and apply a 1.3Vrms sinewave (1 kHz) input signal to both channelso

28、f the amplifier.Ensure that power is on and that the gain controls are fully up.2. While the amplifier is producing power into the loads, apply a short to the output bindingposts of each channel. In other words, apply a jumper between the red and blackbinding posts of each channel. Once this is done

29、, combined AC line current draw forboth channels should be no greater than 13A ac. This is with a 120 volt AC service tothe amplifier. Current may be lower if AC line voltage is lower.3. Remove the short from each channel and verify that the channels recover in to 2 ohmloads. The output should not e

30、xperience any hang up and a full sinewave should bepresent just as it was before a short was applied for this test.4. If the amplifier does not pass any of the above steps, troubleshoot the current limitsection of the amplifier. If steps 2, 3, and 4 above pass, continue to the next testFREQUENCY RES

31、PONSE.l FREQUENCY RESPONSE1, Set load to 8 ohms and scale the input generator to gain 1 watt of power from theamplifier on each channel. Gain controls on the amplifier should be fully up.2. Check frequency response from 2OHz to 20kHz (+I- 0.2OdB) by sweeping randomfrequencies between these extremes.

32、 This is done by verifying the same voltageamplitude at each of the frequencies selected (within 2OHz to 2OkHz). Check bothchannels.l POWER vs. DISTORTION TESTI. Check to ensure that both channels will produce rated power at 2OHz, 2KHz, and 20kHz.into an 8 ohm load.2. While verifying rated power, ch

33、eck that at all frequencies the distortion measurement isless than or equal to 0.03% THD.l THERMAL TEST1. Set input frequency to 1 KHz and short both channels while they are producing power intoa load.2. Apply a short to the output of each channel.3. AC line current draw should be about 11 - 13.5 am

34、peres for both channels. As theamplifier gets hot, there will be some current drift upwards and the fan speed willincrease. This is not a problem as long as the case temperature on the outputtransistors does not exceed 105 degrees C.44. Verify that the NTC circuit causes thermal shutdown after an ex

35、tended period.5. When thermal shutdown occurs, verify AC idle current of less that 0.90 amperesl CM TEST1. Select an 8 ohm load and confirm that this amplifier is producing rated power.2. Check the Common Mode of the amplifier by inserting a 1/4” input jack halfway into eachchannel and observe about

36、 6 dB of output voltage reduction. There will also be a 180degree phase inversion at the output of the channel under test.l OUTPUT NOISE1. Set the amplifier gain controls all the way up, with a 1 kHz 1.3OVrms sinewave inputsignal. Note the output level at full power just below clipping. Adjust gain

37、if needed.2. Remove the input signal connector from the amplifier and measure the residual noiselevel produced into the load by the amplifier. The noise signal should be 107 dB downfrom the full output power point measured. A signal to noise ratio should be better thanor equal to 107dB. Check both c

38、hannels.l FINAL CHECKThis completes the amplifier test procedure for this model. Inspect the amplifier formechanical defects. Inspect the solder connections. Reassemble the amplifier and verifythe amplifiers operation before returning the product to service.PLX 1602 Test Procedure. SET-UP1.2.3.4.5.6

39、.7.Connect a test load to the output terminals of the amplifier.Make sure Mode Switches 1 - 10 are in the default position (1 on, 10 on, all others off)Connect a distortion analyzer with a resolution of O.Ol%, 20-20kHz (or better) to theoutput terminals of the amplifier. Enable the 80kHz low pass fi

40、lter.Connect a dual-channel oscilloscope to the following test points:Chl - a 1 OX (vertical sensitivity - 2V/cm) scope probe to the channel speaker output.Ch2 - a IX scope probe (vertical sensitivity - O.lV/cm) to the distortion analyzeroutput.Set amp gain pots fully clockwise and turn on power swi

41、tch.Connect the output of the signal generator to the input terminals of the amplifier andselect an output of 1.30 VRMS, 1 kHz sine wave.Plug the amplifier into a variac and set up an AC line current monitor.l POWER UP 8 MUTE DELAY TESTCAUTION: To avoid damage to the main printed circuit board, plac

42、e a 50 ohm 225W resistor (100 ohm,240VAC) in series with the high (+) lead on the AC cable during variac ramp up. If the switching powersupply has a shorted device at initial power up, this AC resistor pad will help prevent undue damage. Afterthe amplifier has been fully powered up via the variac, c

43、onfirm that the amplifier has achievedstable operation during idle. Remove AC power from the amplifier and disconnect the seriesresistor for normal operation. Continue with the test & calibration process.Slowly raise the variac voltage and watch for excessive current draw (line currentgreater than 0

44、.5A a.c at 60 Volts). T/I;s is s/;ghf/y less for 240V. Pause at 9OVAC(2OOVAC European) for three seconds until the mute I protect circuit disengages.Continue to 12OVAC (24OV European).Verify that the fan is operating at low speed.3. Turn the power switch off and on a few times to verify the 3 second

45、 power-up mutingdelay. CHANNEL OUTPUT1. Look for amplified signal on the scope for channel 1. Switch the input signal and scopeto channel 2 and repeat output test. Check for noisy / contaminated gain pots byobserving general instability on the distortion waveform while adjusting the gain controlleve

46、ls.2. Select an 8 ohm load and confirm that this amplifier is producing 300 watts at 1 kHz justbelow the point of clipping. Check both channels. BRIDGE MODE1. Turn the power switch off.2. Set Mode Switch #7 in the on position. The gain control, limiter, and filter switch positionson CH2 are disabled

47、 with Mode Switch #7 on.3. Set load to both red output binding posts (CHI positive and CH2 negative).4. Apply a 1.30 VRMS, 1 kHz sinewave input to channel 1 of the amplifier. Check the powerand verify that the output does not immediately collapse. Check for 1000 watts at 8ohms.5. Turn power off and

48、place the amplifier under test back into the Stereo mode with outputloads connected to each channel.l B I A SI. Let the amplifier cool down to room temperature.2. With an input amplitude of 1.3OVrms increase the input frequency to 20kHz. Reduce theinput signal 20dB (80%) from full output. Adjust the

49、 crossover trimpot VR43 (CHl) andVR166 (CH2) for about a 4OOmVpk-pk crossover spike protruding from the noise traceon the oscilloscope. It will be necessary to have the oscilloscope measure unfiltereddistortion from the amplifier in order to see the crossover spike.It is necessary todisable the 80kH

50、z lowpass filter on the analyzer for this test. Further trim so thatthe total distortion for that channel is less than 0.1% THD+N.3. With the trim settings achieved, and with no signal plugged into the amplifier and with an8 ohm load, verify that the AC idle current from the AC service is no more th