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1、Confidential Alesis Service Manual 8-31-0030-A ALESIS MATICA 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 recip
2、ient, 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 Confidenti
3、al Alesis Service Manual 8-31-0030-A Preface This 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
4、 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 a
5、nd 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 a
6、n 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 a
7、nd 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 Alesi
8、s 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 fu
9、lly 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
10、 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 tra
11、nsfer 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
12、 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 authoriz
13、ed representative of Alesis. All Trademarks are property of their respective companies. RadioFans.CN Confidential Alesis Service Manual 8-31-0030-A Warnings TO 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
14、 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 imp
15、ortant 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
16、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 LIAB
17、ILITY 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
18、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 use
19、d batteries according to the manufacturers instruction. RadioFans.CN 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 writ
20、ten 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 produ
21、ct. 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
22、 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
23、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 us
24、ed 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
25、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 instructio
26、ns. 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
27、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 Alesis A4/A8 Service Manual- iv 03/07/03 General Troubleshooting While this manual assumes that the reader has a fundamental understand
28、ing 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
29、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 c
30、old (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 exce
31、ss 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 press
32、ing 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 (vari
33、able 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.
34、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 Alesis
35、 A4/A8 Service Manual- v 03/07/03 Table of Contents PREFACE. 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 Pr
36、otection.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 Hi
37、story .16 INDEX.17 RadioFans.CN 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
38、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. Th
39、ough 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:
40、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 conv
41、entional volt-amp current limiter circuit. The output devices use a new perforated emitter technology unique to MOTOROLA. The output 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 speake
42、rs 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 acco
43、mplished 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 unti
44、l 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 c
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