Alesis QuadraVerbGT Schematic
QuadraVerb GT Service Manual
Revision 1.00
10/17/95
QuadraVerb GT Service Manual------ 1
PREFACE
This document is intended to assist the service technician in the operation, maintenance and repair of the
QuadraVerb GT guitar effects processor. This unit represents one of the building blocks of the complete ADAT
system. Together with the QuadraVerb GT Reference Manual, this document provides a complete description
of the functionality and serviceability of the QuadraVerb GT. 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.
QuadraVerb GT Service Manual------ 2
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: Tadiran
Type: TL-5101
Rating 3.6V
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.
QuadraVerb GT Service Manual------ 3
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. 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. 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.
4. Periods of Non-use. If the product is not used for any significant period of time, the product's AC power supply cord should be
unplugged from the AC outlet.
5. Foreign Objects and Liquids. Take care not to allow liquids to spill or objects to fall into any openings of the product.
6. Water or Moisture. The product should not be used near any water or in moisture.
7. Heat. Do not place the product near heat sources such as stoves, heat registers, radiators or other heat producing equipment.
8. 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.
9. 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.
10. Cleaning. The product should only be cleaned as the manufacturer recommends.
11. 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.
12. 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.
QuadraVerb GT Service Manual------ 4
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 antialiasing 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.
QuadraVerb GT Service Manual------ 5
Table of Contents
PREFACE............................................................................................................II
READ THIS!........................................................................................................II
WARNINGS.........................................................................................................III
SAFETY SUGGESTIONS...................................................................................IV
General Troubleshooting.....................................................................................V
1.0 Schematics....................................................................................................7
2.0 Software History............................................................................................9
3.0 GT MIDI Implementation...............................................................................10
4.0 GT Service Parts List....................................................................................26
Service Manual History........................................................................................30
INDEX..................................................................................................................31
QuadraVerb GT Service Manual------ 6
1 . 0 Schematics
QuadraVerb GT Service Manual------ 7
QuadraVerb GT Service Manual------ 8
2 . 0 Software History
Date Version Comments
07\08\91 1.00 First production release.
05\22\92 1.01 1) Adds global cabinet simulator controls.
2) Fixes erroneous setting of preamp parameters when a program using the
sampling configuration is recalled.
3) Fixes distorted audio when a program using the reverb configuration has its
reverb chorus speed, or depth modulated via MIDI.
1.02 Never released.
10\28\92 1.03 New set of factory programs.
QuadraVerb GT Service Manual------ 9
3 . 0 GT MIDI Implementation
System Exclusive Format
The Quadraverb-GT MIDI System Exclusive message format is as follows:
F0 System exclusive status
00 00 0E Alesis manufacturer id#
07 Quadraverb-GT id#
cc Opcode
dd Data
:
: :
F7 End-Of-Exclusive
OPCODES:
01 - MIDI Editing
F0 00 00 0E 07 01<function#><page#>< value1>< value2>< value3>F7
<function#> = 1=reverb,2=delay,3=pitch,4=eq,7=config, 8=mix, 9=name/mod, 10=preamp
<page#> = 0..n where n is the maximum page # for the selected function
<value1-3> = new parameter value in the following format:
Data: B7 B6 B5 B4 B3 B2 B1 B0 (MSB)
A7 A6 A5 A4 A3 A2 A1 A0 (LSB)
Sent: 0 A7 A6 A5 A4 A3 A2 A1 <value1>
0 A0 B7 B6 B5 B4 B3 B2 <value2>
0 B1 B0 0 0 0 0 0 <value3>
All parameters to be edited must be sent in this format (12 MIDI bytes), regardless of
the number of bits required to transmit the value of the parameter. When the QuadraVerb -GT
receives this message, it will edit the specified parameter to the new value and display it. If the
function and page selected does not exist in the current configuration, the command will be
ignored. If the value received is out of range for the parameter selected, the range will be limited
to a legal value. The function and page numbers for each parameter are shown in the next
section.
02 - MIDI Data Dump F0 00 00 0E 07 02 <program#> <data> F7
<program#> = 0..99 selects individual programs
= 100 selects the edit buffer
= > 100 selects all 100 programs
<data> is in a packed format in order to optimize data transfer. Eight MIDI bytes are used to
transmit each block of 7 QuadraVerb -GT data bytes. If the 7 data bytes are looked at as one 56bit word, the format for transmission is eight 7-bit words beginning with the most significant bit of
the first byte, as follows:
QuadraVerb GT Service Manual------ 10
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