Alesis A-6 Service manual
ALESIS
A6 Andromeda (A6)
Service Manual
P/N: 8-31-0089-C
ATTENTION!
THIS DOCUMENT CONTAINS SENSITIVE
PROPRIETARY INFORMATION. ALL
RECIPIENTS MUST HAVE A CURRENT NON-
DISCLOSURE AGREEMENT ON FILE WITH
ALESIS, LLC.
DO NOT DISTRIBUTE THIS DOCUMENT IN
ELECTRONIC FORM
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 support@Alesis.com.
Copyright © 2003 Alesis, LLC
Confidential Alesis Service Manual 8-31-0089-C
Version History
Ver A: BRS: added new cover page, added Fatar key removal instructions.
Ver B: 6/13/02 BRS: added more debugging tips, added rev C main board.
Ver C: 10/30/03 ATM: Added additional warning information for Battery replacement (per UL)
Confidential Alesis Service Manual 8-31-0089-C
Preface
This document is intended to assist the service technician in the operation, maintenance and
repair of the A6 Andromeda. Together with the A6 Reference Manual, this document provides a
complete description of the functionality and serviceability of the A6. 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
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.
authorize you to be an authorized Service Center. Therefore, if you perform,
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.
Confidential Alesis Service Manual 8-31-0089-C
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 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 manufacturer's instruction.
Confidential Alesis Service Manual 8-31-0089-C
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
and such that nothing will be placed on or against them.
3. Periods of Non-use
cord should be unplugged from the AC outlet.
4. Foreign Objects and Liquids
product.
5. Water or Moisture
6. Heat
7. Ventilation
8. Mounting
9. Cleaning
10. Service
. Do not place the product near heat sources such as stoves, heat registers, radiators or other heat producing
equipment.
. When installing the product, make sure that the product has adequate ventilation. Improperly
ventilating the product may cause overheating, which may damage the product.
. 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.
. The product should only be cleaned as the manufacturer recommends.
. 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.
. AC power supply cords should be placed such that no one is likely to step on the cords
. If the product is not used for any significant period of time, the product's AC power supply
. Take care not to allow liquids to spill or objects to fall into any openings of the
. The product should not be used near any water or in moisture.
11. Damage to the Product
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.
. Qualified service personnel should service the unit in certain situations including
Confidential Alesis Service Manual 8-31-0089-C
1.0 Theory of Operation
d
p
The A6 is a 16-voice digitally-controlled real analog synthesizer.
The heart of the system is a Motorola Coldfire processor on the Main board. The code for the
Coldfire is in flash memory, and is upgradeable through MIDI. There is also a battery-backed
SRAM for holding user data.
There is a secondary processor on the Front Panel Left, an 87C52 running code from an
EPROM. This processor controls the LCD and does the LED muxing. It does not, however,
read the pot values. This is done by the Coldfire.
The analog sounds are generated from 8 Oscillator ASICs that feed 8 Filter ASICs. Each ASIC
contains two voices.
The diagram below shows the majorA6 PCBs and their functions:
Front Panel Left
Micro, EPROM,
LED muxing
pot muxing
switch matrix
LEDs
switches
pots
Analog pot
Control
voltages,
switch data
Main
Coldfire micro
address decoding
flash memory
keyscan ASIC
digital FX
pot/tuning ADC
tuning comparator
ASIC control
MIDI
foot pedals
power regulators
Control
LCD control
Analog pot
voltages,
switch
matrix
Databus
Control,
FX return
Tuning
signal, FX
sen
Front Panel Center
LEDs, switches, pots
Control
LCD
Analog pot
voltages,
switch
matrix
Analog ASIC
4 DACs for analog ASIC control signals
8 Oscillator ASICs
8 Filter ASICs
analog power regulators
Noise,
external
uts
in
Voice busses,
tuning,
FX busses
Analog Master
analog output circuitry (op amps)
analog distortion
analog noise generator
Front Panel Right
LEDs, switches, pots
Confidential Alesis Service Manual 8-31-0089-C
2.0 Test Procedures
This document assumes basic familiarity with the A6 and the A6 User Manual. Please read
Appendix C of the A6 Reference Manual and familiarize yourself with it. It contains useful
information for troubleshooting.
2.10 Power Up Modes
You will need to know the A6 power up modes, since these will be helpful in debugging many
problems. The following chart is taken from the A6 User Manual:
POWER UP
WHILE HOLDING
Soft Button 1 Forces A6 to load default Program and Mix. This is useful if the A6 has received
Soft Button 2 Enters front panel debug mode.
Soft Button 3 Initializes all user RAM. This is also known as a Hard Reset. Warning, this will
FUNCTION
corrupted data, causing it to hang.
erase all User Programs and Mixes, replacing them with the factory default User
Programs and Mixes!
Soft Button 4 Initializes all Global parameters, including tuning tables.
Soft Button 5 Re-calibrates Mod Wheel and Ribbon Controller.
Soft Button 6 Sends software OS out as MIDI Syx Ex dump.
Soft Button 7
Soft Button 8
Enables the A6 to receive software Syx Ex dump (OS or bootloader).
Replaces the factory default User Programs and Mixes with the User Bank
Programs and Mixes. The next time a RAM initialization is done (Soft Button 3),
these banks will be used to initialize the User Banks.
Confidential Alesis Service Manual 8-31-0089-C
2.20 Diagnostic Software Description
The A6 diagnostic software is contained within the boot section of flash memory. The software
is intended to be used to test all of the functionality of the front panel and most of the main
board. The analog boards are not tested in this mode, since those require the main software
engine to be running. Diagnostic mode is entered by holding down soft button 2 while powering
on the unit. When you are in Diagnostic mode, you will see the boot software version in the
headline.
2.21 Passive Ribbon Test
This test is done automatically when the user enters diagnostic mode. It tests the ribbon for
shorts and for proper operation of the left and right calibration points. It is “passive” because it
is done while the ribbon is not being used. In fact, if the ribbon is pressed during this test, it will
fail!
If this test fails, it most likely means the conductive layer of the ribbon (pin 2) is shorted to the
resistive layer (pins 1 and 3). It could also mean that one of the pins (1, 2 or 3) is broken or
shorted.
2.22 Pitch Wheel Center Test
This test is done automatically when the user enters diagnostic mode. It makes sure that the
pitch wheel springs are holding the pitch wheel pot sufficiently within the center of the throw.
2.23 Switch Test
This test is always going on. Simply press a switch! The name of the switch should appear on
the screen, and the “Sw :” should be in inverse characters until the switch is released. In
addition, if there is an LED near the switch, it will light up. If the switch is pressed a second
time, the LED will go off. When the microprocessor detects that a switch has been pressed and
released, the word “PASSED” appears on the screen.
When doing this test, it is only necessary to look at the LED (if there is one). If the LED
corresponding to the switch you pressed goes on (and no others), the switch is good. Looking at
the screen is only necessary for those switches with no LEDs nearby (i.e., the program keys).
Note that if you hold the SHIFT key down while pressing the soft keys, the test associated with
the soft key being pressed will not be performed. This is handy when testing the center board
keys, when you may not want to execute the test.
2.24 Pot Test
Like the Switch Test, the Pot Test is always going on. Simply turn a pot and you should see the
name of the pot on the screen, along with the pot value, which ranges from 0 to 4095. When a
pot is turned, the value should change smoothly corresponding to how much the pot is turned.
The values should stop changing immediately after (within one second) a pot is turned. If a pot
value continues to jitter after you let go, there may be a problem with the pot, the front panel, or
the ADC circuitry on the Digital Main Board.
Confidential Alesis Service Manual 8-31-0089-C
If a pot reaches the nominal min and max values, the word “PASSED” will be displayed on the
screen. The passing minimum value is 11 or less. The passing max value is 4084 or greater. It
is normal if a pot doesn’t go all the way to zero, or all the way up to 4095, due to offsets in the
ADC op amps.
Test Passing min threshold Passing max threshold
Pitch Wheel center value + 1300 center value - 1300
Mod Wheel 1000 3000
Aftertouch 400 4083
Control Foot Pedal 100 2500
Ribbon Right/Left 30 3000
Pots 12 4083
Note that a bad pot may still give a passing message (for example if it jittering), so the user must
use some common sense here. If a pot is constantly jittering, there is a problem with the pot (or
the unit).
Note that the Pitch Wheel, the Mod Wheel, the Continuous Controller Pedal, Aftertouch, and
Ribbon Controller all fall under the pot test. These controllers all have different nominal min
and max values. To speed up the test during production, a regular pedal switch may be plugged
into the CC Pedal jack and used for this test.
For the pitch and mod wheels, make sure the wheels are not electrically swapped. The pitch
wheel is on the left, the mod on the right. The pitch wheel should have a spring and should
bounce back to center.
When doing this test, turn only one pot at a time. If more than one pot is turned at a time, the
test will fail (in boot code V1.20.10 or later), because the software thinks another pot is jittering.
Also, turning more than one at a time may cause the display queue to overflow.
2.25 LED Test
To enter this test, press soft button 1. All of the LEDs on the unit should light up. The yellow
LEDs should be blinking. Hit button 1 again to turn off the LEDs. Note that any LEDs that
were on before this test will be restored and kept on.
The user should make sure that all LEDs go on, that all LEDs are centered in the window, and
all LEDs are the correct color.
2.26 MIDI Test
To perform this test, press soft button 2. A MIDI cable should be connected from MIDI OUT to
MIDI IN. This test will send a series of bytes through the MIDI port and read them back in. If it
passes, the display will read “MIDI TEST PASSED”.
2.27 LCD Test
Confidential Alesis Service Manual 8-31-0089-C
To perform this test, press soft button 3. All of the pixels on the LCD should turn black. Press
any key to exit this test.
2.28 Slow SRAM Test
To perform this test, press soft button 4 and wait a few seconds. This will test the Slow SRAM,
or battery backed RAM, on the Digital Main PCB. The first part of this test will test the RAM
for stuck bits. The second part will test the RAM address lines to make sure there are no address
pins shorted together or open. If this test passes, the display will read “SLOW SRAM TEST
PASSED”.
2.29 Test Completion
The DONE soft key (soft key 8) checks to make sure all of the tests have been performed before
letting the user exit diagnostic mode into normal keyboard mode. If any test has not been
successfully completed, the code will tell the user which test has not been done and remain in
diagnostic mode.
In addition, when all of the buttons and pots on a particular board have been successfully
exercised, the software will tell the user which boards passed (e.g., “CENTER BOARD
PASSED!”) when the DONE soft key is pressed. This is for board testing, when the user is only
interested in the status of that board, not the whole system. The software will tell the user which
switches or pots were missed on the particular board being tested.
Confidential Alesis Service Manual 8-31-0089-C
2.30 Front Panel Test Procedure
Connect the following cables/accessories to the A6 external ports:
2.311 Connect one end of a MIDI cable (4-17-0003) to the MIDI IN port and the other end to
the MIDI OUT port.
2.312 Connect Fatar Foot Switch (93) to the CC PEDAL ¼" jack of the FOOT SWITCHES/
PEDALS ports.
2.313 Connect power cord to A6 power jack.
2.314 Verify that A6 unit has current Bootloader and OS code versions with the following
steps:
a) Switch on power to A6 while holding down round SB#7.
b) Verify on A6 LCD:
ANDROMEDA SOFTWARE
BOOTLOADER V01.20.3x OS
V01.40.xx
Note: If Bootloader version is less than "1.20.31" and/or the OS version is less than
"1.40.xx", updated software should be loaded (xx - latest version).
c) Power down A6.
2.315 Enter test mode by pressing and holding down SB#2, while switching power ON, until
"*** A6 Diagnostic Mode *** " message appears on LCD display. Verify that Blue LED
is on.
2.316 Test LEDs by pressing SB#1. Verify that all LEDs on the Front Panel light up. Note that
the following LEDs should be yellow and flashing:
° "Auto Tune"
° "Audio Ext In"
° "Store"
° "Filter Bypass"
° "BP Invert"
Press SB#1 again to turn off the LEDs.
2.317 Test MIDI function by pressing SB#2. Verify that the message "MIDI TEST PASSED!"
appears on the lower center area of the LCD display.
2.318 Test LCD function by pressing SB#3. Verify that all dark pixels are visible within the
darkened area on the LCD display. Press SB#3 again to restore LCD contrast back to
normal.
2.319 Test LCD contrast pot by turning small contrast knob, found on the right side of the LCD,
back and forth while verifying that the contrast changes.
Confidential Alesis Service Manual 8-31-0089-C
2.320 Test SSRAM function by pressing SB#4. Verify that the messages, first, "TESTING
SLOW SRAM", then, "SLOW SRAM PASSED!" appears on the LCD display.
2.321 Test the Ribbon Controller by starting from the farthest end of either side of the ribbon
and sliding finger across it, while pressing down, from left to right and back, verifying
that the left and right ribbon values increase and decrease while sliding and that the
"PASSED" message appears twice on the LCD display. Note: If only one "PASSED"
message appears on the LCD display, stop test and reject unit.
2.322 Test each and every Potentiometer, one at a time, from one end of the Front Panel to the
other, verifying that both panel and LCD pot names match up and that the "PASSED"
message appears (for every pot) on the LCD display. Note: The MASTER VOLUME
pot will not show up on the LCD display when actuated.
3.323 Test the Pitch/Mod Wheel Assembly by moving the PITCH and MOD wheels while
verifying that both the panel and LCD wheel names match up. Verify that the
"PASSED" message appears on the LCD display. Also, verify that all buttons on the
Pitch/Mod Wheel Assembly actuate their corresponding LEDs and that their panel and
LCD names match up on the LCD display.
2.324 Test the Front Panel switches by pressing every button on the Front Panel, verifying that
both panel and button names on LCD match up and that their corresponding LEDs light
up when pressed (some buttons do not have corresponding LEDs). NOTE: Do not
press/test SB#1-4 -- they were tested in previous steps.
2.325 To test the Aftertouch, press down firmly and hold any of the keys in the keybed until the
"PASSED" message appears on the LCD display.
2.326 Test the Foot Switches/Pedals ports:
a) Connect the Fatar Foot Switch (93) to the CC PEDAL port (¼" jack) and actuating it
while verifying that the "CC PEDAL PASSED" message appears on the LCD
display.
b) Connect the Fatar Foot Switch (93) to the SUSTAIN port (¼" jack) and test by
actuating it while verifying that the "SUSTAIN PEDAL PASSED" message appears
on the LCD display.
c) Connect the Fatar Foot Switch (93) to the SWITCH port (¼" jack) and test by
actuating it while verifying that the "SWITCH PEDAL PASSED" message appears
on the LCD display.
2.327 Press SB#8 to identify the remaining tests to be done.
2.328 Perform remaining tests as required by A6 diagnostic software.
2.329 Follow and repeat steps 1.17 to 1.19 until all remaining tests have been performed.
2.330 If unit passes all required tests mentioned in this document, then unit has passed the Front
Panel Test!
Confidential Alesis Service Manual 8-31-0089-C
Loading...