General_Music_LEM_AMP_2.4_Service_Manual电路图.pdf

1 1 1 1 1 J J J J J Index Soldering 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 flags GENERALMUSIC S.p.A. Sales Division: 47842 S.Giovanni in Marignano (RN) ITALY - Via delle Rose, 12 - tel. 0541/959511 - fax 0541/957404 GENERALMUSIC on the NET: Technical Specifications, Introduction, Test Procedures one positive and one negative low rail (+/-Vcc1) and one positive and one negative high rail (+/-Vcc2). Some component references in the circuitry have the A letter suffix to identify the CH1 channel and the B letter for CH2 channel. Visual CheckVisual CheckVisual CheckVisual CheckVisual Check Use compressed air to clear dust in the amplifier chassis. Before proceed to supply the amplifier check visually the internal assem- bly, if appears an evident damage find the most possible reasons 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. Test InstrumentsTest InstrumentsTest InstrumentsTest InstrumentsTest Instruments Audio Generator Dual Trace Oscilloscope Digital Multimeter 4 500W, 8 300W, 100 10W resistors Variac (0250Vac) SetupSetupSetupSetupSetup Connect the Variac between the mains and the amplifier and set it at zero voltage. Set the amplifier in STEREO MODE and turn full clockwise the LEVEL potentiometers. Connect the audio generator to the channel inputs and set it to 1KHz 775mVRMS (0dB) sinusoidal signal. The procedures that follow must be executed subsequently in the order specified. Supply CheckSupply CheckSupply CheckSupply CheckSupply Check Remove the transformer secondary fuses (located on SUPPLY & PRO- TECTIONS board), set the Variac to the nominal mains voltage, check with the Multimeter the AC supply voltages: FUSE1-FUSE2=551.5Vac FUSE3-FUSE4=903Vac. Re-set the Variac at zero voltage, turn off the amplifier and put the fuses back on its holders. Connect the oscilloscope probes ch1/2 to the channel outputs, before RL1, set both to 20V/div. 200S/div. Set up the Variac slowly monitoring the Outputs with the oscilloscope ch1/2 connected, it should display the sinusoidal input signal amplified with no distortions, if a distortion occur check the POWER AMPLIFIER boards as suggested in the ADVICES section. If the protection trips, turn off the amplifier, wait some minutes and disconnect the supplies from the outputs modules (CN1, CN4 on POWER AMPLIFIER boards), continue to check the supplies. CAUTION: Before re-connecting the output modules to the supplies,CAUTION: Before re-connecting the output modules to the supplies,CAUTION: Before re-connecting the output modules to the supplies,CAUTION: Before re-connecting the output modules to the supplies,CAUTION: Before re-connecting the output modules to the supplies, you must have the capacitors discharged for your safety: connect ayou must have the capacitors discharged for your safety: connect ayou must have the capacitors discharged for your safety: connect ayou must have the capacitors discharged for your safety: connect ayou must have the capacitors discharged for your safety: connect a 100100100100100 10W resistor across the caps and remove the resistor just after 10W resistor across the caps and remove the resistor just after 10W resistor across the caps and remove the resistor just after 10W resistor across the caps and remove the resistor just after 10W resistor across the caps and remove the resistor just after they are discharged.they are discharged.they are discharged.they are discharged.they are discharged. Finally verify the DC supplies on POWER SUPPLIES board: CN2-4 pin 3 (+Vcc2)=+612Vdc CN2-4 pin 4 (+Vcc1)=+361.5Vdc CN2-4 pin 2 (-Vcc1)=-361.5Vdc CN2-4 pin 1 (-Vcc2)=-612Vdc CN3 pin 5=+151Vdc CN3 pin 3=-151Vdc If one or more voltages dont correspond, check the rectifiers, capacitors and transformers disconnecting them from circuitry, refer to schematics. Channels CheckChannels CheckChannels CheckChannels CheckChannels Check The CH1 channel is on the left and CH2 channel is on the right of the chassis. These procedures are intended for one channel at a time, repeat these operation for the other channel. Verify, with the Multimeter, the insulation between the heatsink and the transistors collectors. Verify, with the Multimeter, the PTC resistor value (R133 connected across pin 8 an pin 9 of CN3), it must be between 50 and 200. SETUP:SETUP:SETUP:SETUP:SETUP: Connect the ch1 scope GND clip to CN102 pin 1 (GND terminal). Connect the ch1 probe tip to CN102 pin 2 (AMP output). Connect the ch2 probe tip to D109 anode and set it sensitivity at 5V/div. Set the LEVEL potentiometers full clockwise. The load resistor is disconnected. INITIAL TEST:INITIAL TEST:INITIAL TEST:INITIAL TEST:INITIAL TEST: Increase slowly the Variac. The channel output signals must be symmetri- cal respect the GND without visible distortion and oscillation as shown in Fig.1 Trace A (Trace B shown the amplifier 2nd stage input). If there is a distortion read the section ADVICES and proceed to check the other channel. BIAS ADJUSTMENT:BIAS ADJUSTMENT:BIAS ADJUSTMENT:BIAS ADJUSTMENT:BIAS ADJUSTMENT: Set the generator level at zero, connect the Multimeter across the emitter and collector of TR108, then adjust R132 trimmer to read 2.5Vdc. HIGH RAIL CHECK:HIGH RAIL CHECK:HIGH RAIL CHECK:HIGH RAIL CHECK:HIGH RAIL CHECK: Connect the ch2 probe tip to D103 cathode and set it sensitivity at 20V/ div. When the output signal (Positive half-wave) is less than 30Vp the voltage on D103 cathode must remain constant at 36V, when the output signal exceeds 30Vp the voltage must follow the output signal with 6V offset (see Fig.2 Trace B), to check the negative high rail connect the probe to D114 anode (see Fig.2 Trace C). Connect the 8 300W load on the output and repeat the INITIAL and HIGH RAIL checks. Check the signal clipping, it must occur at 482Vpp (see Fig.3 Trace A,B,C). SIGNAL/CLIP SENSOR CHECK:SIGNAL/CLIP SENSOR CHECK:SIGNAL/CLIP SENSOR CHECK:SIGNAL/CLIP SENSOR CHECK:SIGNAL/CLIP SENSOR CHECK: Set the LEVEL pot to minimum, set the scope timebase at 1V/div. 200S/ div., then increase the level and check the SIGNAL/CLIP led activity: it must turn on (green light) when the amplifier output is higher than 1Vp. Set the scope at 20V/div. and increase the level, check the LIMITER led Fig. 1Fig. 1Fig. 1Fig. 1Fig. 1 Trace A (20V/div.) Trace B (5V/div.) RadioFans.CN 收音机爱 好者资料库 3 3 3 3 3 J J J J J activity: it must turn on (red light) at the amplifier output signal clipping. CURRENT AND SHORT CIRCUIT SENSOR CHECK:CURRENT AND SHORT CIRCUIT SENSOR CHECK:CURRENT AND SHORT CIRCUIT SENSOR CHECK:CURRENT AND SHORT CIRCUIT SENSOR CHECK:CURRENT AND SHORT CIRCUIT SENSOR CHECK: Set both the scope channels sensitivity to 0.5V/div., connect the scope ch1 GND clip at CN3 pin 2 (AMP output) and the probe tip at TR106 (NPN) emitter, connect the ch2 probe tip at TR113 (PNP) emitter. Set the generator to have approx. 1Vp on the emitters: their difference must be less than 0.2V on the peaks (see Fig.4 Trace A & B). Connect a 4 500W load. Increase the input signal, the output current limiter must keep the emitter voltages, both half channel, at 1.5Vp approx. (see Fig.5 Trace A). Temporarily short the amplifier output: the current limiter must keep the emitter voltages (both half channel) at 1 approx. (see Fig.5 Trace B). OFFSET SENSOR CHECK:OFFSET SENSOR CHECK:OFFSET SENSOR CHECK:OFFSET SENSOR CHECK:OFFSET SENSOR CHECK: Set the Variac to zero voltage output, disconnect the amplifier load and the supply connection from the Power Supply & I/O Board (CN2-4), turn on the amplifier, connect temporarily (by means of a suitable conductor wire) CN2 pin 2 to +15Vdc (CN3 pin 5), the PROTECT led must turn on in 5 seconds approx. Remove the connection, wait until the leds turn off and after some sec- onds repeat the check with -15Vdc (available on CN3 pin 3), the led PROTECT must turn on again. BIAS CHECK:BIAS CHECK:BIAS CHECK:BIAS CHECK:BIAS CHECK: Disconnect ch2 probe. Connect the ch1 scope GND clip to CN2 pin 1 (GND terminal) and its probe tip to CN2 pin 2 (AMP output). Adjust the generator level until the sinewave appears at full screen amplitude, no crossover distortion must be detectable: if necessary re-adjust R132. BANDWIDTH CHECK:BANDWIDTH CHECK:BANDWIDTH CHECK:BANDWIDTH CHECK:BANDWIDTH CHECK: Set ch1 scope sensitivity at 20V/div., increase the generator level to have 80Vpp, sweep the generator frequency from 20Hz to 20KHz: the output level must have not detectable level changes. SLEW RATE CHECK:SLEW RATE CHECK:SLEW RATE CHECK:SLEW RATE CHECK:SLEW RATE CHECK: Set the scope sensitivity to 10V/div. 1S/div. and set the generator to 1KHz square wave mode. Check the output square wave rising and falling edge slopes: both must be 10V/S or more as shown in Fig 6. Inputs & Protections Board CheckInputs & Protections Board CheckInputs & Protections Board CheckInputs & Protections Board CheckInputs & Protections Board Check These procedures are intended for one channel at a time, repeat these operations for the other channel. SETUP:SETUP:SETUP:SETUP:SETUP: Connect the ch1 probe to amplifier input of the channel under test and set it at 500mV/div. 200mS/div. Connect the ch2 probe to amplifier output of the channel under test and set it at 10mV/div. 200mS/div. Set the audio generator at 1KHz sinus. 775mVRMS (0dB). Set the LEVEL potentiometers full clockwise. The load resistor is disconnected. AMPLIFIER GAIN CHECKAMPLIFIER GAIN CHECKAMPLIFIER GAIN CHECKAMPLIFIER GAIN CHECKAMPLIFIER GAIN CHECK Check the output levels: at 775mV position the output voltage must be 461.5Vp. SIGNAL TO NOISE RATIO CHECKSIGNAL TO NOISE RATIO CHECKSIGNAL TO NOISE RATIO CHECKSIGNAL TO NOISE RATIO CHECKSIGNAL TO NOISE RATIO CHECK Disconnect the audio generator the output signal (noise) must be less 1mV. AdvicesAdvicesAdvicesAdvicesAdvices Check the channels one at time to determine which is right (note: if you have a spare amplifier module that you know as right, use it). 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 Fig. 2Fig. 2Fig. 2Fig. 2Fig. 2 Fig. 3Fig. 3Fig. 3Fig. 3Fig. 3 Fig. 5Fig. 5Fig. 5Fig. 5Fig. 5 Trace A (0.5V/div.) Trace B (0.5V/div.) Fig. 4Fig. 4Fig. 4Fig. 4Fig. 4 Trace A (0.5V/div.) Trace B (0.5V/div.) one leg of each emitter pin and measure the emitter-collector resistance on each device. Unsolder and lift one leg of each base pin and check the base-collector resistance of each transistor and replace any that measure as a short. If all the transistors are OK, unsolder and lift one leg of each diode and check them. Check the circuit board for open foil traces. Use the Multimeter as Ohm-meter 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 circuitry of the positive low rail. If the positive cycle appears distorted, you can assume that the problem is in the circuitry of the negative low rail. If the high rails appear distorted or are not modulating as shown in figure, then the problem probably exists somewhere in the circuitry of the re- spective (+ or -) defective high rail. Refer to the schematics. Fig. 6Fig. 6Fig. 6Fig. 6Fig. 6 Trace A (10V/div.) Trace B (20V/div.) Trace A (20V/div.) Trace C (20V/div.) Trace B (20V/div.) Trace A (20V/div.) Trace C (20V/div.) RadioFans.CN 收音机爱 好者资料库 J J J J J 4 4 4 4 4 5 5 5 5 5 J J J J J Spare Part ListSpare Part ListSpare Part ListSpare Part ListSpare Part List CodeRef.Description AccessoriesAccessoriesAccessoriesAccessoriesAccessories 277328Owners Manual AssemblyAssemblyAssemblyAssemblyAssembly PHC667004Front Panel PHC667003Level Knob PHC238003Transformer 300WTransformer 300WTransformer 300WTransformer 300WTransformer 300W PHC130294Mains Cord (EU) PHC110007Power Switch AssemblyAssemblyAssemblyAssemblyAssembly PHC768019PHC768019PHC768019PHC768019PHC768019Phones BoardPhones BoardPhones BoardPhones BoardPhones Board 140207Horizontal Female Jack Socket PHC768133PHC768133PHC768133PHC768133PHC768133Display Board (Pcb# 290-60241)Display Board (Pcb# 290-60241)Display Board (Pcb# 290-60241)Display Board (Pcb# 290-60241)Display Board (Pcb# 290-60241) 080742*Led 3mm Wide Diffused Red-Grn 080710*Led 3mm 60deg Diffused Yel 080705*Led 3mm 60deg Diffused Red PHC074001*10K Rotary Potentiometer PHC768016PHC768016PHC768016PHC768016PHC768016Power Supply & I/O Board (Pcb# 290-60240)Power Supply & I/O Board (Pcb# 290-60240)Power Supply & I/O Board (Pcb# 290-60240)Power Supply & I/O Board (Pcb# 290-60240)Power Supply & I/O Board (Pcb# 290-60240) 230557*1uh Hor Coil For Amplifier 140228*Horizontal Jack Stereo Socket 110307*Relay 24V / 2 Switch 5A 250V 100051*4558 Dual Operational Amplifier PHC090000*A1015GR TO92 Ln Pnp Transistor PHC090001*C1815GR TO92 Ln Npn Transistor 080232*5V1 1W 5% Zener Diode 080156*1N4002 1A 100V Rectifier Diode 080103*1N4148 100mA 75V Signal Diode 070241*100K 20% Horizontal Linear Trimmer 070121*1K 20% Horizontal Linear Trimmer 060540*3K3 1W 5% Resistor 060481*820E 5W 10% Resistor 060214*4E7 5W 10% Wire Resistor 030085*2u2 50V 20% Vert Electrolytic Bipolar Capacitor 110020*T5A Fuse 5x20mm (EU) 110003*T3.15A Fuse 5x20mm (EU) 080605*KBL02(6) 4A 200V Rectifier Diode Bridge 080293*15V 1W 5% Zener Diode 060441*470E 5W 10% Resistor 030543*3300u 63V 20% Snap-In Electrolytic Capacitor PHC727596PHC727596PHC727596PHC727596PHC727596 * * * * * Power Amplifier Board (Pcb# 9610042) With HeatsinkPower Amplifier Board (Pcb# 9610042) With HeatsinkPower Amplifier Board (Pcb# 9610042) With HeatsinkPower Amplifier Board (Pcb# 9610042) With HeatsinkPower Amplifier Board (Pcb# 9610042) With Heatsink 100931*MC34081 Single J-Fet Operational Amplifier 090917*MJE350 TO126 Pnp Transistor 090916*MJE340 TO126 Npn Transistor 090201*2N5401 TO92 Pnp Transistor 090200*2N5550 TO92 Npn Transistor 090194*BC560 TO92 LN Pnp Transistor 090183*BC550 TO92 LN Npn Transistor 080261*10V 1W 5% Zener Diode 080245*7V5 1W 5% Zener Diode PHC080007*LT6A04 6A Fast Recovery Diode 080156*1N4002 1A 100V Rectifier Diode 080103*1N4148 100mA 75V Signal Diode 070084*220E 20% Vertical Linear Trimmer 070065*100E 20% Vertical Linear Trimmer 060075*0E33 5W 5% Wire Resistor 030247*10u 25V 20% Vert Electrolytic Bipolar Capacitor 340750*TO126 Mica Washer 340078*TO220 Insulated Bush 090920*MJE802 TO126 Npn Darl Transistor 090863*TIP36C TO218 Pnp Transistor 090862*TIP35C TO218 Npn Transistor PHC080008*Ptc 90 PTH9L04BE222TS2F330 Note:Note:Note:Note:Note: Each spare part is single quantity unless otherwise specified. Asterisk prefix explanation: Omitted= First l