Alesis-Matica900-pwr-sm维修电路原理图.pdf

Confidential Alesis Service Manual 8-31-0030-A ALESISMATICA 500/900 (A4/A8)Service Manual P/N: 8-31-0030-A The information in this document contains privileged and confidential information.It is intended only for the use of those authorized by Alesis. If you are not the authorized, intended recipient, you are hereby notified that any review, dissemination, distribution or duplication of this document is strictly prohibited. If you are not authorized, please contact Alesis and destroy all copies of this document. You may contact Alesis at or at .Copyright Alesis, LLC RadioFans.CN 收音机爱 好者资料库Confidential Alesis Service Manual 8-31-0030-A PrefaceThis document is intended to assist the service technician in the operation, maintenance and repair of the Alesis device. Together with the User Reference Manual, this document provides a complete description of the functionality and serviceability of the Device. Any comments or suggestions you may have pertaining to the document are welcome and encouraged. READ THIS! In addition to any purchase price that Alesis may charge as consideration for Alesis selling or otherwise transferring this service manual (“Manual”) to you, if you are not a service and repair facility (“Service Center”) authorized by Alesis in writing to be an authorized Service Center, Alesis sells or transfers the Manual to you on the following terms and conditions: Only Service Centers authorized by Alesis in writing are authorized to perform service and repairs covered by an Alesis warranty (if any), and transfer of the Manual to you does not authorize you to be an authorized Service Center. Therefore, if you perform, or if the Manual is used to perform, any service or repairs on any Alesis product or part thereof, any and all warranties of Alesis as to that product and any service contract with Alesis for that product shall be voided and shall no longer apply for such product, even if your services or repairs were done in accordance with the Manual.All service or repairs done by you or with reference to the Manual shall be solely your responsibility, and Alesis shall have no liability for any such repairs or service work. All such service or repairs are performed at the sole risk of the person performing the service or repairs. You agree that all such work will be performed in a competent, professional and safe manner at all times and to indemnify and fully hold Alesis and its successors and assigns harmless in the event of any failure to so perform. Your purchase of the Manual shall be for your own ultimate use and shall not be for purposes of resale or other transfer. As the owner of the copyright to the Manual, Alesis does not give you the right to copy the Manual, and you agree not to copy the Manual without the written authorization of Alesis. Alesis has no obligation to provide to you any correction of, or supplement to, the Manual, or any new or superseding version thereof. Alesis shall have the right to refuse to sell or otherwise transfer repair parts or materials to you in its sole discretion. You shall not use, sell or otherwise transfer spare or replacement parts supplied by Alesis to you (i) to repair or be used in products manufactured for or by third parties or (ii) to any third parties for any purpose. You shall not make any warranties or guarantees with respect to the products of Alesis or the use thereof on behalf of Alesis or in your own name. The foregoing describes the entire understanding related to sale or transfer of the Manual to you, and no other terms shall apply unless in a writing signed by an authorized representative of Alesis. All Trademarks are property of their respective companies. RadioFans.CN 收音机爱 好者资料库Confidential Alesis Service Manual 8-31-0030-A WarningsTO REDUCE THE RISK OF ELECTRIC SHOCK OR FIRE, DO NOT EXPOSE THIS PRODUCT TO WATER OR MOISTURE. 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. 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. Regarding the Power Supply Fuse CAUTION: The product under service may employ the use of a replaceable fuse. Danger of fire or electrocution if fuse is incorrectly replaced. Replace with only the same type or equivalent type recommended by the equipment manufacturer. Regarding the Internal Battery CAUTION: The product under service may employ the use of a internal battery. Danger of explosion if battery is incorrectly replaced. Replace only with the same or equivalent type recommended by the manufacturer. Dispose of used batteries according to the manufacturers instruction. RadioFans.CN 收音机爱 好者资料库Confidential Alesis Service Manual 8-31-0030-A Safety Instructions 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. Power Cord Protection. AC power supply cords should be placed such that no one is likely to step on the cords and such that nothing will be placed on or against them. 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 A4/A8 Service Manual- iv 03/07/03 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 A4/A8 Service Manual- v 03/07/03 Table of ContentsPREFACE. ii WARNINGS . ii SAFETY SUGGESTIONS .iii General Troubleshooting.iv 1.00 Theory of Operation .1 1.10 Input Section.1 1.20 Pre-Amp Section .2 1.30 Main Amplifier Section.2 1.40 Output Device Protection.3 1.50 Bias Circuit .3 1.60 Speaker Protection.4 1.70 Fan Speed Control.4 1.80 Thermal Management System.5 2.00 Updates and Corrections.5 2.10 Stripped Heat Sinks.5 2.20 New Case Bracket Insulator(s).7 2.30 Transformer Insulators.8 3.00 Troubleshooting.9 4.00 A4 Service Parts List.10 4.10 A8 Service Parts List .13 5.00 Service Manual History .16 INDEX.17 RadioFans.CN 收音机爱 好者资料库Alesis A4/A8 Amplifiers Service Manual- 1 03/07/03 1.00 Theory of Operation The A4/A8 amplifiers are basic stereo amplifiers. They have 0dBm input sensitivities for rated output at 4?, with the ability to drive any load impedance from 2? to an open circuit. They have balanced inputs via Neutrik combination connectors providing XLR and 1/4 TRS connections and also a barrier strip. The output of the amplifier is obtained by way of four five way binding posts. Reference designations in the text refer specifically to the A4 amplifier except where otherwise noted. Though reference designations between the two units are different, the designs are virtually identical. The only significant differences occur in the output section (since the A8 is required to handle much more power than the A4). Here are some of the major features and building blocks of the Matica: An input balanced to unbalanced converter. A second stage pre-amp and an amplifier gain stage utilizing a monolithic front end with discrete complimentary transconductance stage and a complimentary output stage in a common collector configuration. Output device protection is accomplished with a conventional volt-amp current limiter circuit. The output devices use a new perforated emitter technology unique to MOTOROLA. Theoutput devices are driven by similar technology devices, but they have been optimized for extremely linear current gain with a unity gain bandwidth (Ft) of 50 MHz. The speakers are protected by output relays. They are activated during the first 3 to 5 seconds the amplifier is turned on. Also, if a DC condition exists at the output of the amplifier or the amplifier is driven to full output below 5Hz the relays will be activated. Thermal management and protection are accomplished with a large heavy aluminum extruded heat sink the is fan cooled. If the sink gets warmer than 55 deg. C, the fan is automatically stepped up in speed and if the heat sink gets warmer than 80 deg. C the fan is run at high speed and the output relays are activated to disconnect the load until the unit has cooled to 65 deg. C. There is also a unique feature of the amplifier fan circuit in that when the amplifier is providing an output signal of a little more that a watt the fan speed is modulated or increased by the signal. This will help get longer run times with the amplifier under extreme load conditions. 1.10 Input Section The input stage is made up of a dual Signetics 5532A op amp. This is a low noise selected version of the 5532. One half of the dual is used for each channel. The circuit is a basic balanced to unbalanced converter. It can be driven unbalanced but 6dB differences in gain may result for various hookups. If the (+) input is driven with the (-) input grounded the gain will be unity. If the (+) input is driven with the (-) input left open there will be a gain reduction of 6dB. This is not recommended as a noisier condition may result. If the (-) input is driven, gain will be unity and will not change with the grounding or ungrounding the (+) input The maximum input level before clipping in about +21dBm. Since there is no level control in front of the converter this is the maximum input level for the amplifier. Connections to the Alink connector are between R1, R2 and R3, R4. These are provided so an outboard impedance may be connected to modify the gain and overload characteristics as well as its frequency response. Following the amplifier is a passive low pass (R7, C1) filter that begins to limit the high frequency gain of the amplifier. RadioFans.CN 收音机爱 好者资料库Alesis A4/A8 Amplifiers Service Manual- 2 03/07/03 1.20 Pre-Amp Section The pre-amp section also uses the Signetics 5532A op amp. The circuits of the pre-amp are of opposing signal polarity to provide push pull characteristics and are connected via the stereo/bridge switch. Each of the two pre-amp channels has 15.7 dB of gain but channel A is inverting and channel B is not. Since the main amplifier is inverting, channel A will not invert the signal and channel B will. Doing this facilitates two things. When the stereo/bridge switc