LEM-Procon400P-pwr-sm 维修电路原理图.pdf
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1、1 IndexSoldering point.Male connector.Female connector.M/F faston connector.Test point.Supply voltage.Logic supply ground.Analog supply ground.Chassis ground.Earth ground.Flag joined with one or more flagsGENERALMUSIC S.p.A. Sales Division: 47842 S.Giovanni in Marignano (RN) ITALY - Via delle Rose,
2、12Phone +39(0)541/959511 - Fax +39(0)541/957404 - Internet: Technical specifications, transistor packages, Procon 400p test procedures.2Procon 750p, Procon 1000p test procedures.3Procon 1250p, Procon 1500p test procedures.67Procon 750p schematic.8Procon 400p schematic.9Procon 1250p schematic.10Proco
3、n 1000p schematic.Procon 1500p schematic.11Procon 1800p schematic.12Procon 2200p schematic.13Spare part list.4Procon 1800p, Procon 2200p test procedures. 5with the same signal name inscribed.ATTENTIONObserve precautions when handling electrostatic sensitive devices. NoticeService must be carried out
4、 by qualified personnel only. Any tampering carried out by unqualified personnel during the guarantee periodwill forfeit the right to guarantee.For a correct operation of the instrument, after having switched off, be careful to wait at least 3 seconds before switching on again.To improve the devices
5、 specifications, the schematic diagrams may be subject to change without prior notice.All components marked by this symbol have special safety characteristics, when replacing any of these components use onlymanufacturers specified parts. The () micro symbol of capacitance value is substituted by U.T
6、he () omega symbol of resistance value is substituted by E. The electrolytic capacitors are 25Vdc rated voltage unless otherwise specified.All resistors are 1/8W unless otherwise specified.All switches shown in the OFF position. All DC voltages measured to ground with a voltmeter 20KOhm/V.service ma
7、nualschematic diagramsCODE: 270312Power Amplifiersprocon plusRadioFans.CN 收音机爱 好者资料库2PROCON400p - Test proceduresPRECAUTION To prevent short circuit during any test, the oscilloscope must be EARTH INSULATED, this occurs because some test require to connect its probe to the amplifi er output, non-com
8、pliance may cause damages to oscilloscope inputs circuitry. Before removing or installing any modules and connectors, disconnect the amplifi er from AC MAINS and measure the DC supply voltages across each of the power supply capacitors. If your measurement on any of the caps is greater than 10Vdc, c
9、onnect a 100E 60W resistor across the applicable caps to discharge them for your safety. Remember to remove the discharge resistor immediately after discharging caps. Do not power up the amplifi er with the discharge resistor connected. Do not check the amplifi er with the speakers connected use the
10、 appropriate load resistors only. BE CAREFUL increasing the Variac you must not exceed the nominal mains voltage plus its tolerance (see specifi cations) any upper volt-age can be cause of damage.VISUAL CHECK Use compressed air to clear dust in the amplifi er chassis. Before proceed to supply the am
11、plifi er check visually the internal assembly, if appears an evident damage fi nd the most possible rea-sons that cause it. Check the wiring cables for possible interruptions or shorts. If the damage has burnt a printed circuit board dont try to repair it, replace with a new one.TESTING GEAR Audio G
12、enerator Dual Trace Oscilloscope Digital Multimeter 4E 300W, 8E 450W, 100E 60W resistors Variac Digital Thermometer (not indispensable)SETUP Connect the Variac between the Mains and the amplifi er and set it at zero voltage. Turn full counter-clockwise the LEVEL potentiometers. Connect the audio gen
13、erator to the channel inputs and set it to 1KHz 775mVrms (0dBu) sinusoidal signal. Connect the two scope traces to the amplifi er outputs, before the relay, and set them in DC at 20V/div. 2mS/div.SUPPLY CHECK Verify with the Multimeter the insulation between the heatsinks and all transistor collecto
14、rs mounted on them; placing the multimeter tips between the screw heads and the collector pins you can exclude an erroneus reading due to the insulation of the heatsink anodization. Verify with the Multimeter the NTC (RT1) and R1 paralleled resistor value, it must be about 1080ohm (at 25c). Disconne
15、ct the amplifi er module supplies of each channel (red and yellow wires). Set the Variac to the nominal mains voltage, turn on the Amplifi er, then check with the Multimeter the AC supply voltages: F1-F2 = 292Vac. RED secondary wires = 879Vac. Re-set the Variac at zero voltage, turn off the amplifi
16、er and recon-nect the supplies at each amplifi er module. Set up the Variac slowly monitoring the oscilloscope screen, it should display no signal; if you notice a DC voltage or a protection trips check the amplifi er as suggested in the ADVICES. As soon as the +12VF supply circuit reaches its nomin
17、al value, all cooling fans run at their minimum and the speaker output relais (J201-202) switch. When the Variac ac voltage reaches the nominal voltage verify the DC supplies as follow: +VCC = +596Vdc -VCC = -596Vdc U101 pin 8 = +120.5Vdc U101 pin 4 = -120.5Vdc U403 pin 3 = +120.5Vdc If one or more
18、voltages dont correspond, check the rectifi ers, ca-pacitors and transformers disconnecting them from cir cuit ry.CHANNEL CHECK Be sure you have dis con nect ed the load re sis tor. Increasing the input sig nal also the output signal raise ac cord ing ly, it must be sym met -ri cal without vis i ble
19、 dis tor tion or os cil la tion as shown in figure (note: the fi g ure is rep re sent a tive dont re fer to the levels dis played). If there is a dis tor tion read the sec tion ADVICES. When the input sig- nal exceeds -20dBu (20Vpp on output) the fans turn at their max i mum speed. Firstly you must
20、check the channel without load, after-wards you must repeat the check with the loads attached, the following table reports the approx. maximum level obtainable with this amp: out level in level no load 113Vpp +1.5dBu 1CH 4E 91Vpp -0.2dBu 2CH 4E 82Vpp -2.0dBu Bridge 8E 161Vpp -2.3dBuLEVEL METER ADJUS
21、TMENT Check if the clip led lights at -2dBu on input (80Vpp on output), if necessary adjust the trimmers W301/2 on dis play board.OFFSET ADJUSTMENT Set the input level at minimum (no signal), the output dc offset voltage must be within range 20mV, if necessary adjust the VR201 trimmer (for each chan
22、nel) to be within this range.BIAS ADJUSTMENT No bias adjustment is necessary for this amplifi er circuitry.ADVICES If you have determinate that the problem is a short on a rail, you must check the output transistors. To determine which transistor devices are bad, use a soldering iron to lift one leg
23、 of each emitter pin and measure the resistance across emitter and collector of each device. Unsolder and lift one leg of each base pin and check the base-collector resistance. Replace any device that measure as a short. If all the transistors are OK, unsolder and lift one leg of each diode and chec
24、k them. Check the circuit board for open foil traces. Use the Multimeter to check the resistors, particularly the base and emitter resistors of damaged transistor. If the input sinewave appears to be distorted during the negative cycle, you can assume that the problem is located somewhere in the cir
25、cuitry of the positive rail. If the positive cycle appears distorted, you can assume that the problem is in the circuitry of the negative rail. The dc voltages printed on the schematics are measured with the amplifi er in steady state without input signal and nominal mains volt-age supply, it can be
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