《Alesis-MMT8-seq-sm 电路图 维修手册.pdf》由会员分享，可在线阅读，更多相关《Alesis-MMT8-seq-sm 电路图 维修手册.pdf（44页珍藏版）》请在收音机爱好者资料库上搜索。
1、ALESIS MMT-8 (MT) Service Manual P/N: 8-31-0018-A RadioFans.CN 收音机爱 好者资料库 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 fu
2、nctionality 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
3、”) 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 per
4、form 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 warr
5、anties 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
6、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
7、 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 Manua
8、l, 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 rig
9、ht 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 partie
10、s 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 unle
11、ss 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 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 insid
12、e 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 im
13、portant 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
14、 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 LIA
15、BILITY 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
16、 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 us
17、ed batteries according to the manufacturers instruction. RadioFans.CN 收音机爱 好者资料库 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 th
18、e 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 powe
19、r 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.Fo
20、reign 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 o
21、ther 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 recom
22、mends. 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. Th
23、e 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 ser
24、vice 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 c
25、hange in performance or does not operate normally, or e.The enclosure of the product has been damaged. Alesis MMT-8 Service Manual 1.00 v General Troubleshooting While this manual assumes that the reader has a fundamental understanding of electronics and basic troubleshooting techniques, a review of
26、 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 microprocesso
27、r 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
28、 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 - Wig
29、gling 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 Componants - Somtimes
30、 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 c
31、an 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 freque
32、ncy 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. Alesis MMT-8 Service Manual 1.00 vi TABLE OF CONTENTS PREFACE .ii READ THIS!.ii WARNINGS
33、.iii SAFETY SUGGESTIONS.iv General Troubleshooting.v 1.00 General Description.1 2.00 Power Supply .1 2.10 Battery Backup.1 3.00 The 8031 Micro Controller.1 3.10 Reset .1 3.20 Memory Mapped I/O.2 4.00 Tape I/O.2 5.00 MIDI I/O.3 6.00 Keypad Decoding .3 7.00 Metronome Output.4 8.00 Updates and Correcti
34、ons.4 9.00 Troubleshooting.4 10.00 Software History .5 11.00 MIDI Implementation .8 12.00 Service Parts List.14 13.00 Service Manual History.16 INDEX .17 Alesis MMT-8 Service Manual 1.00 1 1.00 General Description The MMT-8 MultiTrack Recorders power lies mainly in the sophistication of its software
35、. The most powerful troubleshooting tools available to the technician are the a good working knowledge of the MMT-8s operation and the software history in section X.X. Most problems with the MMT-8 arise from either user error, or older software. The hardware is very simple and should normally prove
36、to be problem to troubleshoot. Please note here that there are sveral revisions of main PCB and 2 revisions of keypad boards. While latest versions of the main PC Board include most of the hardware updates, older board revisions will require some additions to bring them up to the current factory spe
37、cifications. These updates are discussed fully in section X.XX. 2.00 Power Supply 2.10 Battery Backup Battery backup is actually more complicated than it might first appear, as it depends on a good system reset (see section X.X for details) in order to function properly. The actual backup circuit co
38、nsists of a battery (3V - 3.6V Lithium), a 10K resistor (R76) for checking standby current (see below), a steering diode (D5), a filter capacitor (C13), and a transistor/resistor/diode combination (Q11, R79, D6) that acts as a steering diode. This combination may be missing on older board revisions,
39、 and must be installed (see section X.X) to prevent data corruption due to a significant difference between Vcc, and the amplitude of the data buss. SRAM standby current should always be checked. While the unit is off, check the voltage across R76. If the voltage is higher than 80mV (specification,
40、although a 1 to 20mV range is more normal) then a problem exists. Usually it indicates a bad (or simply wrong) SRAM, or a short, somewhere along the MEM PWR line. Note, that for a short time, Sony 58256-PM (high power) SRAMs were being installed at the factory, causing batteries to drain in about 1
41、year. They should be replaced with low power versions (58256-LP) when found, in order to eliminate excess battery drain. We are currently using Hitachi 62256ALPs as replacements. CAUTION:Danger of explosion if battery is incorrectly replaced. Replace only with the same type or equivalent type recomm
42、ended by the equipment manufacturer. Battery Manufacturer: Tadiran Type: TL-5101 Rating 3.6V 3.00 The 8031 Micro Controller The 8031 MPU is the heart of the MMT-8s control section. It handles everything from keypad input and MIDI I/O, to sequencing. Note that the 8031 data buss serves a dual purpose
43、. This buss multiplexes between low order addresses (1st 8 bits), and data. Latch U11 is used to hold the low order address half, during 8031 read and write cycles. The EPROM (U12) is used to hold 8031 program information. The SRAMs (U9, U10) hold system variables, as well as user sequence data. Z1 provides the 12MHz 8031 clock. MIDI I/O is handled through the 8031s built in RXD (Read Serial Data), and TXD (Transmit Serial Data) por
免费区 
