BXR_200_Service_Manual 电路图.pdf

BXR 200 BASS EXTENDED RANGE COMBO & HEAD SERVICE MANUAL CONTENTS: Notices Specifications Circuit description Parts lists: Preamp PCB assembly Power amp PCB assembly Chassis assembly Cabinet assembly Miscellaneous Schematics/diagrams Fender Musical Instruments Corp. 8860 E. Chaparral Road Suite 100 Scottsdale, AZ 85250 RadioFans.CN 收音机爱 好者资料库 BXR 200 (This is the model name for warranty claims) SERVICE MANUAL MARCH 1996 IMPORTANT NOTICE: The information contained herein is CONFIDENTIAL and PROPRIETARY to Fender Musical Instruments Corp. It is disclosed solely for use by qualified technicians for purposes of equipment maintenance and service. It is not to be disclosed to others without the expressed permission of Fender Musical Instruments Co. All specifications subject to change without notice. For warranty repair service, only Fender specified part numbers are to be used. It is recommended they also be used for post-warranty maintenance and repair. Parts marked with an asterisk (*) indicate the required use of that specific part. This is necessary for RELIABILITY and SAFETY requirements. DO NOT USE A SUBSTITUTE! A coded naming convention is used in the description of certain parts. The codes and what they mean are as follows: CAPACITOR CODES HARDWARE CODES CAP AE=Aluminum ElectrolyticBLX=Black Oxide CAP CA=Ceramic AxialCR=Chrome Plated CAP CD=Ceramic DiskHWH=Hex Washer Head CAP MPF=Metalized Polyester FilmM=Machine Screw CAP MY=MylarNI=Nickel Plated CAP PFF=Polyester Film/FoilOHP=Oval Head Phillips PB=Particle Board RESISTOR CODESPHP=Pan Head Phillips PHPS=Pan Head Phillips Sems RES CC=Carbon CompSMA=Sheet Metal A Point RES CF=Carbon FilmSMB=Sheet Metal B Point RES FP=Flame ProofSS=Stainless Steel RES MF=Metal FilmTF=Thread Forming RES WW=Wire WoundZI=Zinc Plated RadioFans.CN 收音机爱 好者资料库 BXR 200 SPECIFICATIONS Product Release No.:PR 286 (This is not a model number) POWER AMPLIFIER SECTION: Power Output:200 Watts RMS Distortion at 200 watts:Less than .1% 1kHz, below compression Less than 1% 1kHz, maximum compression Rated Load Impedance:4 Sensitivity:1.03V RMS Input Impedance:22k DELTACOMP Range:20db PREAMP SECTION: Input Impedance:Input 1 Greater than 420k (typically greater than 1M ohm in the passband) Input 2 136k Sensitivity for 200 watts:Input 1 2.2mV GAIN at maximum, all toneInput 2 4.4mV controls at “0” detent, no enhancement activated. Shelving Tone Controls:LOW +/- 12dB at 60Hz HIGH +/- 12dB at 10 kHz Graphic Equalizer:+/- 12dB at 80,140,250,450,800,1.4k,2.5k, 4.5k and 8kHz. Dimensions:BXR 200 ComboBXR 200 Head Height:25-1/2(64.8 cm)6-29/32 inches (17.5cm) Width: 21-1/2(54.6 cm) Depth: 13-1/2(34.3 cm) Weight:72 lbs.(32.7 kg)27 lbs (12.3 kg) Product specifications are subject to change without notice RadioFans.CN 收音机爱 好者资料库 BXR 200 CIRCUIT DESCRIPTION PREAMP J1 is a high sensitivity input which can be driven with as much as 2.5 volts RMS. J2 is a low sensitivity input which is recommended for Bass Guitars with active pickups, and can handle as much as 5 volts RMS. U1A is a “cheater” Sallen Key filter with gain. R79 and C82 create a gradual boost in the high frequencies. This sets up the initial response of the amplifier. C43 and C44 are used for local power supply decoupling for the first two op-amp stages. This minimizes noise and hum in the front end of the preamp. U1B is a variable gain stage. The Gain Control is used as the feedback resistor. This allows a gain adjustment from less than 1 to about 10. At the input of U2A, the DEEP enhancement switch boosts and extends the low-frequency response. Within the negative feedback loop, the BRIGHT enhancement switch adds high frequency “sparkle”. The output of U2A drives the Notch Filter circuit. When engaged, this filter provides a narrow band notch of about 20db at 650 Hz. The signal then feeds a unity gain amp (U2B) and couples to the first tone control stage. From the active tone controls the signal is routed to the second Gain stage (U8B). If the DeltaComp is off, switch S5B places Q1 & Q2 into the feedback loop, where they are biased asymetrically to provide non- symetrical soft clipping, which simulates a tube sound. The diode junctions Q1,Q2, CR1 and CR2 drop a constant knee-voltage independent of current. As the signal increases above a certain level, the constant voltage alters the feedback current to the op-amp in a non-linear fashion. This non-linear transfer characteristic is what rounds off the resulting signal into a tube-type, soft-clipping waveshape. With the DeltaComp engaged, the soft-clipping circuit is disabled. CHORUS The input signal to the Chorus circuit is capacitivly (C61) coupled to U10A, which drives the Bucket Brigade Device (BBD) U13. Trimpot R105 sets the DC bias for U10A and U12A. When properly adjusted, the output from U10A & U12A will display symmetrical clipping. (Refer to the adjustment procedure on the service diagram). The BBD is clocked by U14 at 180kHz. The 180kHz carrier clock is Frequency Modulated by the Low Frequency Oscillator U11, which deviates the carrier at maximum DEPTH from 60kHz to 300kHz. The RATE of deviation runs from about 0.3Hz to 8.7Hz. The FM deviation on top of the BBD delay results in a pleasing choral effect. C62 and R107 (U10A) provide pre-emphasis above 7kHz. At the output of U12A, R121 and C74 provide the de-emphasis. This helps to reduce noise. C64, C65 and C67 filter out clock noise. The Dry and Chorus signals are summed at U12B and then fed to the power amplifier. Via the Chorus select switch or the footswitch, the Chorus effect can be switched on or off. The collector of Q4 provides the control voltage which enables U11, and determines the state of JFET Q5. A 15Vdc from Q4 enables U11 to oscillate, and pinches off JFET Q5, which removes the ground from the node between R123 & R124. DELTACOMP The signal from the preamp feeds from P1B pin 4, through a ribbon cable, to P1A on the power amplifier PCB. The signal couples (via C1) to the unity gain amplifier U1B. U1B contains a closed loop (gain of 1) negative feedback path, along with positive feedback through the inverting Operational Transconductance Amplifier (OTA) U2. U1B and U2 make up the gain reduction circuit for the DeltaComp clip protection feature. BXR 200 DELTACOMP (Cont) The attack and release circuit for the DeltaComp is made up by the Diode, Resistor, and Capacitor network which drives the Base of Q19. Comparator U1A senses the voltage from the Collectors of Q20 & Q21. When the power amplifier approaches clipping on a positive swing, the collector of Q5 pulls up R56, which turns on Q20, transferring 16Vdc to the collector, pulling down R60. This causes the output (pin 1) of U1A to switch from +15Vdc to 15Vdc, lighting the DeltaComp/Clip Led. Note: when the DeltaComp is disabled, the Led indicates clipping of the output stage. WIth the DeltaComp enabled, the Led indicates an active DeltaComp circuit. The negative control voltage from R60 also feeds through P1A to P1B on the preamp PCB. The voltage is routed to the DeltaComp switch (S5A), located on the front panel. With the switch engaged, the control voltage is sent back through the ribbon cable (via P1 pin 6) to the attack/release circuit. The negative voltage drives through Diodes CR31-CR34, and charges Capacitors C16-C19 all at once in parallel as a one pole filter through a single time constant of R60 X (C6+17+18+19) or 2.2k X 8.8 uF = 19.4 mSec. As they charge, Q19 turns on and provides current to pin 5 of the OTA (U2). The current controls the output amplitude of U2. The inverted signal from U2 mixes with the input to U1B providing cancellation which reduces amplitude of U2. The inverted signal from U2 mixes with the input ot U1B providing cancellation which reduces the input to the power amplifier. This prevents the amplifier from clipping. When the output of the power amplifier is reduced, the output of U1A toggles back to +15vdc. Due to the blocking action of Diodes CR31-CR34, Capacitors C16-C19 are forced to discharge as a 4-pole filter with different time constants through R55. R51 prevents Parasitic oscillation while Zener CR30 provides 2 slopes which results in smoother limiting. When the power amplifier approaches clipping on a negative swing, R62 is pulled low, turning on Q22 which pulls up the Base of Q21, transferring 16vdc to the collector. POWER AMPLIFIER JFET Q1 and associated components provide a 4-5 second turn-on delay for the audio input to the power amplifier. When the power is switched on, Capacitor C5 charges through Resistor R7. The negative Gate voltage pinches off the JFET, removing the ground from the input of the amplifier. When the power is switched off, C5 immediately discharges through Diode CR1, grounding the input of the amplifier. TROUBLESHOOTING TIP: Check for proper operation of this circuit when experiencing excessive turn-on or turn-off “Pops”, or no output when signal applied to the input. Many times the JFET itself can be the culprit. NOTE: Excessive turn-off “Pops” can also be caused by uneven discharge of the +/- power supplies. Usually a mismatch in the Filter Capacitors will cause this problem. Its easy to look at both supplies on an oscilloscope. Invert one scope input and check for even discharge to zero volts. Q4 is the current source for the Differential Amplifier (Q2,Q3). For the Diff amp to work properly, one half of the current from the current source must flow through each leg of the Diff amp. If the same amount of current flows through each leg of the Diff amp, the voltage drop across resistors R14 &R15 must be the same. If not, there will be a DC offset at the output of the amplifier. The overall gain of the amplifier is set up around the Diff amp. R16 (27k) is the feedback resistor and R17 (1k) is the pull-down resistor. Rfb +Rpd Rpd = Av. Therfore 27k + 1k 1k = 28k 1k = 28Av. Q9 & Q10 make up a voltage amplification stage. Again, to operate properly, the same amount of current must flow trhough these transistors. Thus the voltage drop across R20 & R21 must be the same. Diodes CR16-CR9 (BYV26D) make up the Fixed Bias circuit for the output transistors. The bodies of the Diodes are mounted through the heatsink to properly track the temperature of the transistors. These Diodes were selected because they exhibit a 2mV decrease in Knee Voltage for every 1 degree (Celsius) increase in temperature. The Collectors of Q9 & Q10 are at 0 volts. Therefore the Bias Diodes provide 2 voltage drops (1.2 volts) to the Base of Driver Transistors Q13 & Q14. One Diode drop (0.6 volts) Biases on the Driver Transistors. The remaining 0.6 volts drops across the output transistors (Q15-Q18) in parallel, Biasing them on. BXR 200 Transistors Q11, Q12, and associated components comprise the Current Limiting or Short Proof protection circuit. There are usually two conditions which demand excessive output current from the amplifier. A shorted speaker cable, or a load impedance which is below the minimum rating of the amplifier. If these conditions occur, the voltage drops across the Emitter Resistors (.33 5 Watt) will dramatically increase. On the positive side of the amplifier, C11 charges through R29 & R34. On the negative side C12 charges through R30 & R35. Htis will cause Q11 & Q12 to turn on. This limits the amount of signal which is available to the Base of the Driver Transistors (Q13 & Q14). CR20-CR23 make up a latching circuit that senses the signal through R22. This ensures that Q11 & Q12 turn on hard in conduction. When the fault condition is removed from the output, the current limiting circuit will remain latched up until the input signal is removed. Q13 & Q14 are the Driver Transistors for the output section. Q15-Q18 are the output transistors. Notice on the schematic that the Base resistors carry the “Fp” designation. Htis indicates a Flame Proof/Fuse Type resistor. They wont burn and they act like a fuse when exposed to an over-current condition. This prevents catastrophic damage to the output section. If an output transistor shorts Base to Collector or Base to Emitter, the resistor will simply open. IN many cases the amplifier will continue to operate, but at a reduced power level. An increase in distortion may also become apparent. When replacing these resistors, ALWAYS use the Fuse Type OEM part. PARTS LIST NOTE: SHADED ITEMS ARE FOR REFERENCE ONLY PREAMP PRINTED CIRCUIT BOARD ASSEMBLY QTY PART # DESCRIPTION REFERENCE DESIGNATION 5048451000BUTTON PUSH OFF WHITES1-S5 1033379000CABLE RIBBON 3 CKT 10”P3B 1049334000CABLE RIBBON 3 CKT 20”P4B 1048914000CABLE RIBBON 8 CKT 7”P1B 1048845000CABLE RIBBON 12 CKT 3-3/4”P7B 1033605000CAP AE RDL .15uF 50V 20%C75 1038689001CAP AE AX .47uF 100VC8 2028458000CAP AE RDL 1uF 50V 20%C68,72 4026517001CAP AE AX 2.2uF 50VC4,16,42,45 12038692001CAP AE AX 10uF 35VC9,18,21,24,27,30,33,36,39,41,48,51 2028456000CAP AE RDL 22uF 25V 20%C63,81 1028471000CAP AE RDL 47uF 50V 20%C59 1028479000CAP AE RDL 220uF 25V 20%C70 1038873001CAP CA 22PF 100V LLC5 1004026000CAP CD 22PF 1000V 10%C69 3038698001CAP CA 47PF 100V 10%C3,58,80 1007029000CAP CD 220PF 1000V 10%C67 1039264001CAP CA 1500PF 100V LLC15 4038703001CAP CA .1uF 50V LLC43,44,83,84 1027278000CAP MPF .1uF 63V 10%C60 2027280000CAP MPF .15uF 63VC13,14 1027281000CAP MPF .22uF 63VC82 2030933000CAP PFF .0012uF 50V 5%C46,47 2033579000CAP PFF RDL .0015uF 100V 10%C65,71 2030936000CAP PFF .0022uF 50V 5%C37,38 2030939000CAP PFF .0039uF 50V 5%C34,35 2033582000CAP PFF RDL .0039uF 100V 10%C61,66 1033583000CAP PFF RDL .0047uF 100V 10%C62 BXR 200 PARTS LIST PREAMP PRINTED CIRCUIT BOARD ASSEMBLY (CONT) QTY PART # DESCRIPTION REFERENCE DESIGNATION 2030943000CAP PFF .0068uF 50V 5%C31,32 2030929000CAP PFF 820PF 50V 5%C49,50 2033588000CAP PFF RDL .01uF 100V 10%C1,2 2030946000CAP PFF .012uF 50V 5%C28,29 1036234000CAP PFF RDL .015uF 100V 10%C7 2030950000CAP PFF RDL .022uF 50V 10%C25,26 3033590000CAP PFF RDL .022uF 100V 10%C10,11,12 2033591000CAP PFF RDL .033uF 100V 10%C17,40 2030954000CAP PFF .047uF 50V 5%C22,23 4033592000CAP PFF RDL .047uF 100V 10%C6,64,73,74 2030959000CAP PFF RDL .082uF 50V 5%C19,20 2031087000CONTROL SNAPIN 25K 2B W/DETENTR19,22 (LOW/HIGH TONE CONTROLS) 9040673000CONTROL SLIDE 20MM 50K CTRDETR57-63,77,78 (EQUALIZER) 2027945000CONTROL SNAP IN 100K B TAPERR95,100 (RATE, DEPTH) 1031090000CONTROL 100K 10A/100K 5CR8 (GAIN) 1019994000CONTROL T-POT 100K 20% PC MTGR105 6006260001DIODE 1N4448 SIGNAL LLCR1-6 1027421000HDR .1 CTR 12 CKT SQ PINP7A 2027410000HDR .1CTR 3CKT AW PINP2A, P4A 12016795000IC DUAL OP AMP TL072U1-12 1029671000IC MN3007 BUCKET BRIGADEU13 1029672000IC MN3101 CLOCK GEN/DRIVERU14 2030771000JACK PCB 2/CD SCCJ4,5 (SEND, RETURN) 10