Alesis-QuadraVerbQ2-ep-sm维修电路原理图.pdf

Alesis QuadraVerb II 2.00 I 07/19/06 ALESIS QUADRAVERB II SERVICE MANUAL V2.00 12/12/95 RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 II 07/19/06 PREFACE This document is intended to assist the service technician in the operation, maintenance and repair of the QuadraVerb II Digital Stereo Effects Processor. Together with the QVII Reference Manual, this document provides a complete description of the functionality and serviceability of the QVII. Any comments or suggestions you may have pertaining to the document are welcome and encouraged. WARNINGS TO REDUCE THE RISK OF ELECTRIC SHOCK OR FIRE, DO NOT EXPOSE THIS PRODUCT TO WATER OR MOISTURE. CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN The arrowhead symbol on a lightning flash inside a triangle is intended to alert the user to the presence of un-insulated dangerous voltage within the enclosed product which may be of sufficient magnitude to constitute a risk of electric shock to persons. The exclamation point inside a triangle is intended to alert the user to the presence of important operating, maintenance and servicing instructions in the literature which accompanies the product. CAUTION Danger of explosion if battery is incorrectly replaced. Replace only with the same type or equivalent type recommended by the equipment manufacturer. Battery Manufacturer: Panasonic/Matsushita Type: BR2325 Rating 3V, 5mA REPAIR BY ANY PERSON OR ENTITY OTHER THAN AN AUTHORIZED ALESIS SERVICE CENTER WILL VOID THE ALESIS WARRANTY. PROVISION OF THIS MANUAL DOES NOT AUTHORIZE THE RECIPIENT TO COMPETE WITH ANY ALESIS DISTRIBUTOR OR AUTHORIZED REPAIR SERVICE CENTER IN THE PROVISION OF REPAIR SERVICES OR TO BE OR MAKE REPAIRS AS AN AUTHORIZED SERVICE CENTER. ALL REPAIRS DONE BY ANY ENTITY OTHER THAN AN AUTHORIZED ALESIS SERVICE CENTER SHALL BE SOLELY THE RESPONSIBILITY OF THAT ENTITY, AND ALESIS SHALL HAVE NO LIABILITY TO THAT ENTITY OR TO ANY OTHER PARTY FOR ANY REPAIRS BY THAT ENTITY. RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 III 07/19/06 SAFETY SUGGESTIONS Carefully read the applicable items of the operating instructions and these safety suggestions before using this product. Use extra care to follow the warnings written on the product itself and in the operating instructions. Keep the operating instructions and safety suggestions for reference in the future. 1. Power Source. The product should only be connected to a power supply which is described either in the operating instructions or in markings on the product. 2. Grounding the Plug. This product has a 3-wire grounding type of plug (a plug with a grounding pin) for safety purposes. This plug can only be used in a grounding power outlet. If the plug does not insert into the outlet you are using, the outlet probably is not a grounding type of power outlet. Contact your electrician to replace the obsolete outlet with a grounding type of outlet instead of defeating the safety feature of the grounding type of plug. 3. Periods of Non-use. If the product is not used for any significant period of time, the products AC power supply cord should be unplugged from the AC outlet. 4. Foreign Objects and Liquids. Take care not to allow liquids to spill or objects to fall into any openings of the product. 5. Water or Moisture. The product should not be used near any water or in moisture. 6. Heat. Do not place the product near heat sources such as stoves, heat registers, radiators or other heat producing equipment. 7. Ventilation. When installing the product, make sure that the product has adequate ventilation. Improperly ventilating the product may cause overheating, which may damage the product. 8. Mounting. The product should only be used with a rack which the manufacturer recommends. The combination of the product and rack should be moved carefully. Quick movements, excessive force or uneven surfaces may overturn the combination which may damage the product and rack combination. 9. Cleaning. The product should only be cleaned as the manufacturer recommends. 10. Service. The user should only attempt the limited service or upkeep specifically described in the operating instructions for the user. For any other service required, the product should be taken to an authorized service center as described in the operating instructions. 11. Damage to the Product. Qualified service personnel should service the unit in certain situations including without limitation when: a. Liquid has spilled or objects have fallen into the product, b. The product is exposed to water or excessive moisture, c. The AC power supply plug or cord is damaged, d. The product shows an inappropriate change in performance or does not operate normally, or e. The enclosure of the product has been damaged. RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 IV 07/19/06 General Troubleshooting While this manual assumes that the reader has a fundamental understanding of electronics and basic troubleshooting techniques, a review of some of the techniques used by our staff may help. 1. Visual Inspection - A short visual inspection of the unit under test will often yield results without the need of complex signal analysis (burnt, or loose components are a dead giveaway). 2. Self Test - Alesis products that utilize microprocessor control contain built in test software which exercises many of the units primary circuit functions. Self test should always be done following any repair to ensure basic functionality. 3. Environmental Testing - Applying heat and cold (heat gun/freeze spray) will often reveal thermally intermittent components (Clock crystals, I.C.s, and capacitors are particularly prone to this type of failure). 4. Burn in Testing - Leaving a unit running overnight often reveals intermittent failures such as capacitors that begin to leak excess current after a significant amount of time. 5. Cable Checks - Wiggling cables can reveal intermittent failures such as loose cables or poorly soldered headers. Remember to check power supply cables as well. 6. Flexing the PC Board - Poor solder joints and broken traces can often be found by pressing the PC Board in various places. 7. Tapping Components - Sometimes tapping on a component (particularly crystals) will cause it to fail. 8. Power Down/up - Turning the unit off and back on rapidly several times may reveal odd reset and/or power supply failures. 9. Reset Threshold - A Variac (variable transformer) can be used to check reset threshold levels. This can be particularly useful in helping customers with low line problems. 10. Compressors - Using a compressor/limiter is often helpful when attempting to solve low level noise problems, as well as assisting with DAC adjustments. 11. Sweep Tests - Sweep generators are very useful in checking the frequency response envelopes of anti-aliasing filters. 12. Piggybacking - Piggybacking I.C.s is particularly useful when troubleshooting large sections of logic. This is especially true when working with older units. RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 V 07/19/06 Table Of Contents PREFACE.ii WARNINGS.ii SAFETY SUGGESTIONS .iii General Troubleshooting.iv 1.00 General Description.1 2.00 Power Supply .1 2.10 PUP Circuit.1 3.00 Analog Signal Paths .2 3.10 Audio Input Section.2 3.20 Audio Output Section .2 4.00 A-D/D-A Converters.3 4.10 Analog to Digital.3 4.20 Digital to Analog.3 5.00 Digital Signal Paths.4 5.10 The 8031.4 5.11 Reset.4 5.12 SRAM.5 5.20 DSP.5 5.21 Clock Sources and VCOs.6 5.30 MIDI Hardware.6 5.40 Encoder Interface.7 5.50 Footswitch interface .7 6.00 Appendix 1 Updates and Corrections.A-1 6.10 Important Production Changes.A-1 6.11 VCO Mod .A-1 6.12 SRAM Current Increase.A-2 6.13 Main PCB change. .A-2 6.14 Reset Circuit Change.A-2 6.15 Revision A & C Input Changes.A-6 6.16 Revision A. Sampling Modification.A-7 6.17 Revision A & C VCO Changes.A-8 7.00 Appendix 2 Test Procedures .B-1 7.10 Self Test.B-1 7.20 Further Testing.B-1 7.21 Audio.B-1 7.22 Digital I/O .B-1 7.23 MIDI .B-1 8.00 Appendix 3 Helpful Hints & Common Solutions.C-1 9.00 Appendix 4 Schematics.D-1 9.10 Revision A.D-3 RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 VI 07/19/06 9.20 Front Panel Control I/O. .D-5 9.20 Revision A Component I.D.D-6 9.30 Revision C Component I.D.D-7 10.00 Appendix 5 Software History .E-1 11.00 Appendix 6 MIDI Implementation.F-1 11.10 V1.0X .F-1 11.20 V2.0X .F-21 12.00 Appendix 7 Service Manual History.G-1 13.00 Appendix 8 Service Parts List.H-1 RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 1 07/19/06 1.00 General Description The QuadraVerb II, and other digital reverbs, achieve their results by slicing analog signals into segments, and then converting them to a numeric value, corresponding to the amplitude of the signal at that particular instant. These values are then mathematically manipulated, and stored at various locations in a memory loop for eventual playback. By varying the placement and amplitude of incoming samples, discrete time delays are achieved. When mixed together, and converted back into analog, these delays simulate the reflections associated with natural reverbs, and delays, as well as non natural effects such as reverse reverbs, and gated reverbs. The added capabilities of an 80C31 micro controller allow for user manipulation and storage of algorithm parameters. Some of the PCBs in the unit have undergone revision. The reference designators used in the text apply to the REV. C Main PCB schematic and Comp. I.D. unless otherwise noted. 2.00 Power Supply J13 is the AC power input. Its voltage is derived from the a 20 volt/ampere external transformer. The Q2 draws about three quarters of an amp while in operation. SW1 connects the AC power jack to the input of the power supply which generates +12V, +5V, and -12V. The +12V rail is generated by a voltage doubler (C4, D8, D6, and C20) supplying roughly +20V DC (and about a volt of ripple) to the input of regulator U15. The +12V output of U15 is filtered by C23. The -12V rail is generated in a similar method through a negative voltage doubler (C13, D9, D10, and C21), a -12V regulator (U17), and filtered by C31. The +5V rail requires a rectifier diode (D4), five input filter capacitors (C9, C19, C22, C24, C51), a +5V regulator (U16), and an output filter capacitor (C29). 2.10 PUP Circuit Since the Q2 is used as outboard gear in audio recording studios, it is important not to generate audible thumps at the outputs during power up. These are caused by applying power to the output amplifiers in a non symmetrical manner, and in extreme cases this could actually damage studio monitors. To prevent this situation the Q2 employs a Power UP mute circuit that effectively eliminates any power up transients at the output jacks. The RESET signal (see section 5.11) is routed through R116 to the base of Q9, which in turn controls other transistors that apply power to the output amplifier U18. C49 adds a reasonable delay after the RESET signal goes high, so that the power supply is fully stabilized before it is engaged to the output amplifier. D21 acts as a switch to quickly discharge C49 in case of intermittent power loss. When Q9 is turned on it starts a chain of events that turns on Q6, Q8 and finally Q7. The biasing resistors for these transistors are: R118, R115, R177, R112, R113, R110, and R111. C27 is a bypass capacitor for the positive supply while C25 serves to bypass the negative supply. RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 2 07/19/06 3.00 Analog Signal Paths 3.10 Audio Input Section The Q2 can be used in several stereo or mono audio applications. Additionally it can support both balanced and single ended configurations. A balanced circuit requires three analog connections per channel (i.e. signal +, signal -, and ground). A single ended application requires only two connections (signal and ground). Regardless of the application, the audio signals are routed to and from the unit via balanced stereo 1/4 phono plugs which utilize tip, ring, and sleeve connections. The input jacks J6 and J7 are interconnected such that any signal plugged into J7 will be automatically routed to J6 as long as a phone plug is not already inserted into J6. The input signal from J7s tip is routed to op amp U22A by means of a simple RC network. C17 filters any high frequency while R57 sets the op amps ground reference while also acting as a fairly high input impedance (510K). Finally, R48 protects the op amps input from transients. Op amp U22B is used for balanced signals. If a mono plug is used, the non inverting input is automatically grounded through the RC network of C79, R97, and R96. If however a stereo plug is used, that RC network is used to match the input impedance as well as to provide a high frequency filter. Since tip and ring input impedances must be matched, these resistors are all 1% tolerance. The output from op amp U22B is now sent to U26A. Its input resistor (R56) is used with the right input potentiometer to allow for a gain of 10. Finally this signal is routed to the A to D converter (U14) through a DC blocking capacitor (C10) and current limiting resistor R81. Also clamping diodes (D16 and D17) limit the A to D input from roughly ground to 5 volts. J6 has an identical input section built around op amp U26C, U22D, and U22A. 3.20 Audio Output Section The left output channel is routed from the D-A (see sec. 4.20) through R58 and R65 to the inputs of op amp U26D, which is configured as a differential amp with R55 and R59 setting the gain to two. C28 and C46 act as high frequency attenuators. Note that single ended mode occurs when a mono plug is inserted into the output jack. The output of op amp U26D is routed through a DC blocking capacitor (C26) and is then scaled by the output potentiometer for proper output level. Op amp U18C and U18D are the left channels output amplifiers and have 6dB when single ended mode is selected on the output jack. This is accomplished through a series of input and feedback resistors (R68, R67, R99, R104, R105, R98, R15, R77, R69, and R74). The output jack is terminated with R106 and R107, along with C80 and C15 to ensure amplifier stability. The right output channel is identical and is built around op amps U26D, U18A, and U18B. RadioFans.CN 收音机爱 好者资料库Alesis QuadraVerb II 2.00 3 07/19/06 4.00 A-D/D-A Converters 4.10 Analog to Digital The A to D is a 128 times over sampling Philips 7360 high performance device. It is a stereo part utilizing high Sigma-Delta conversion techniques that eliminates the need for sample and holds, and extensive anti aliasing filters. The right channel is input through R81, while R45 and C74 are the feedback network to the A to Ds internal input buffer amplifier. R47 and R46 provide negative and positive inputs to the A to Ds internal sigma delta modulator. C25 is a small filter cap placed between these inputs. The left input is identical and uses R43, C69, C33, R37, and R38. C68, C71, C72, and C73 are the bypass filters for the internal voltage reference. C44 al