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1、Alesis MidiVerb IV Service Manuali03/05/99 Alesis MIDIVERB IV STEREO EFFECTS PROCESSOR Service Manual V 1.00 6/13/95 RadioFans.CN 收音机爱 好者资料库 Alesis MidiVerb IV Service Manualii03/05/99 PREFACE This document is intended to assist the service technician in the operation, maintenance and repair of the

2、MidiVerb IV Stereo Effects Processor. Together with the MidiVerb 4 Reference Manual, this document provides a complete description of the functionality and serviceability of the Midiverb IV. Any comments or suggestions you may have pertaining to the document are welcome and encouraged. READ THIS! In

3、 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

4、 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 Cente

5、r. 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

6、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

7、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 th

8、e 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 o

9、bligation 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

10、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

11、 own name. The foregoing describes the entire understanding related to sale RadioFans.CN 收音机爱 好者资料库 Alesis MidiVerb IV Service Manualiii03/05/99 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 arro

12、whead 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

13、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 manufactur

14、er. 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 REPAI

15、R 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

16、OTHER PARTY FOR ANY REPAIRS BY THAT ENTITY. Alesis MidiVerb IV Service Manualiv03/05/99 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

17、 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.

18、 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 out

19、let. 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, rad

20、iators 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 manufa

21、cturer 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

22、. 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.

23、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 a

24、n inappropriate change in performance or does not operate normally, or e. The enclosure of the product has been damaged. Alesis MidiVerb IV Service Manualv03/05/99 General Troubleshooting While this manual assumes that the reader has a fundamental understanding of electronics and basic troubleshooti

25、ng 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

26、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 rev

27、eal 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 t

28、ime. 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. Tap

29、ping 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 res

30、et 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 us

31、eful 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. Alesis MidiVerb IV Service Manualvi03/05/99 Table Of Contents

32、 PREFACE.ii READ THIS!.ii WARNINGS.iii SAFETY SUGGESTIONS .iv General Troubleshooting.v 1.00 General Description.1 2.00 Power Supply.1 2.10 Battery Backup .1 3.00 Analog Signal Paths .1 3.10 Input.1 3.20 Output.2 4.00 A-D/D-A .2 4.10 A-D .2 4.20 D-A .2 5.00 Digital Signal Paths.3 5.10 RESET.3 5.20 M

33、4 ASIC .3 6.00 The Front Panel.5 6.10 The Keypad .5 6.20 Display LEDs.5 6.30 Disassembly .5 7.00 Test Procedures .7 7.10 Self Test .7 7.20 Further Testing. .7 8.00 Troubleshooting.8 9.00 Schematics.9 10.00 Software History .13 11.00 MIDI Implementation.15 OVERVIEW .15 THE CHANNEL BYTE.15 THE OPCODE

34、BYTE.15 SYSTEM INFO DATA.16 PROGRAM TABLE DATA.17 EDIT BUFFER DATA.17 ALL USER PROGRAMS DATA.17 SINGLE PROGRAM DATA .17 STORE PROGRAM DATA.17 NOTES .17 12.00 Service Parts List.18 13.00 Service Manual History.20 INDEX.21 Alesis MidiVerb IV Service Manual103/05/99 1.00 General Description The MidiVer

35、b IV is a continuation of the Alesis line of quality studio signal processors. As is the tradition at Alesis, much of units complex functions are incorporated into an LSI ASIC, reducing parts count and cost, as well as increasing reliability and serviceability. The MidiVerb IV pushes the concept of

36、integration further than any previous processors, adding hardware to the ASIC that was previously discreet components. 2.00 Power Supply The M4 power supply begins with the 9 Volt A.C. adapter (Alesis P3 type). Input from J8 is R.F. filtered by C35 before on/off switch SW1. From there it is split fo

37、r the +12V, -12V, and +5V rails. The +12V rail consists of a voltage doubler (C11, C18, and D3, D5), a 7812 regulator, and a filter capacitor (C16). The -12V rail is a mirror of the +12V rail, consisting of voltage doubler (C12, C19, and D4, D6), a 7912 regulator, and a filter capacitor (C20). The +

38、5V rail consists of a rectifier diode (D2), an input filter capacitor (C5), a 7805 regulator, an output filter capacitor (C10) and a multitude of 0.1F bypass capacitors. Note that the raw +5V line used by the microprocessor reset, and the SRAM power supply, and is located at the input to the 7805 re

39、gulator. Likewise, the +12 V and -12V raw supply lines are available for use by the LCD. 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 5.10 for details) in order to function properly. The actual backup ci

40、rcuit consists of a battery (3V Lithium), a 10K resistor (R21) for checking standby current (see below), a steering diode (D8), a filter capacitor (C32), and a transistor/resistor/diode combination that acts as a steering diode, while maintaining a high enough supply voltage to prevent SRAM data corruption. SRAM standby current should