Alesis DEQ224 User manual

ALESIS
DEQ224 (ME1)
Service Manual
P/N: 8-31-0115-A
ATTENTION!
THIS DOCUMENT CONTAINS SENSITIVE
PROPRIETARY INFORMATION. ALL
RECIPIENTS MUST HAVE A CURRENT NON-
DISCLOSURE AGREEMENT ON FILE WITH
ALESIS DISTRIBUTION, 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
[email protected].
Copyright © 2002 Alesis Distribution, LLC
Confidential Alesis ME1 Service Manual 8-31-0115-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
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 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.
All Trademarks are property of their respective companies.
Confidential Alesis ME1 Service Manual 8-31-0115-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 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.
Confidential Alesis ME1 Service Manual 8-31-0115-A

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. 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.
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, 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 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.
9. Cleaning. The product should only be cleaned as 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 instructions.
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 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.
Confidential Alesis ME1 Service Manual 8-31-0115-A

Confidential Alesis ME1 Service Manual 8-31-0115-A
General Troubleshooting
While this manual assumes that the reader has a fundamental understanding of electronics
and basic troubleshooting techniques, a review of some of techniques may help.
°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).
°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.
°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).
°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.
°Cable Checks - Wiggling cables can reveal intermittent failures such as loose
cables or poorly soldered headers. Remember to check power supply cables as
well.
°Flexing the PC Board - Poor solder joints and broken traces can often be found
by pressing the PC Board in various places.
°Tapping Components - Sometimes tapping on a component (particularly
crystals) will cause it to fail.
°Power Down/up - Turning the unit off and back on rapidly several times may
reveal odd reset and/or power supply failures.
°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.
°Compressors - Using a compressor/limiter is often helpful when attempting to
solve low level noise problems, as well as assisting with DAC adjustments.
°Sweep Tests - Sweep generators are very useful in checking the frequency
response envelopes of anti-aliasing filters.
°Piggybacking - Piggybacking I.C.s is particularly useful when troubleshooting
large sections of logic. This is especially true when working with older units.
°Assembly/Disassembly Organization - When removing assemblies, organize
screws and clips with the assemblies that they were removed from. Organizer
trays save a lot of time during re-assembly since similar screws and clips will not
be mixed with each other.

SPECIFICATION
Description of the Controls
There are twenty-four channel buttons on the DEQ224. These are
the [BAND SELECT] buttons. Above each button is a number
like “25” or “19k.”These stand for the audio frequencies,
measured in Hertz (Hz), which are selected for editing by pressing
the [BAND SELECT] buttons below them.
Situated just right of the [BAND SELECT] buttons you will find
three larger buttons. The one in the very middle is the [POWER]
button. On either side of that are the [DOWN] and [UP]
buttons, which are used to edit the gain amount of the frequency
you have selected with the [BAND SELECT] buttons. (It is also
possible to select and edit several frequencies at once; more about
this later.) The [DOWN/UP] buttons are also used to select
programs in Program mode.
Directly above these three buttons are three more buttons: the
[BYPASS],[STORE],and [CHANNEL/EXIT] buttons. Their
functions are as follows:
[BYPASS]
When this button is first pressed, a red LED will light. This means
the DEQ224 is in Bypass mode. As long as this LED is lit,
incoming audio will pass through the unit without being affected
by the DEQ224. This is useful for comparing the “equalized”
signal with the original signal so you can decide if you like the edit
you made. Press the button again to get out of Bypass mode and
hear the effect.
[STORE]
Once you have made an edit you would like to keep, press this
button to enter Store mode. From there you can decide which
of the 30 User locations will become the new home for the
edited Program. You can also copy the settings from Channel A
to Channel Bas you store a program. For more information on
this function, see page 36.
[CHANNEL/EXIT]
This button serves a dual purpose:
1. While in Program mode, pressing this button will cycle the
DEQ224 through 3 modes. You can select Channel A,
Channel B or you can Link A and B together which will cause
the settings for Channel B to “mirror”the settings for Channel
A. This is useful for quickly setting up a program without
having to make independent adjustments for each channel.
2. If you’re in the middle of some other activity, such as editing
or storing, pressing this button will allow you to “exit”to
Program mode.
Audio Input
Input Connectors: 2 Impedance-Balanced 1/4”TRS
jacks
Nominal Input Level: -10dBV (-15dBFS)
Maximum Input Level: +5dBV (1.78 Vrms)
Input Impedance: 10kO
Audio Output
Output Connectors: 2 Impedance-Balanced 1/4”TRS
jacks
Nominal Output Level: -10dBV (-15dBFS)
Maximum Output Level: +5dBV (1.78 Vrms)
Output Impedance: 220O
SERVICE MANUAL
MODEL:DEQ224

Audio Performance
Signal To Noise Ratio: >96 dB A-Weighted, Analog In
to Analog Out
THD+N: <0.007%,Analog In to Analog
Out
Frequency Response: 22-22kHz ± 0.50dB , Analog In
to Analog Out
Power Consumption: 15 Watts Max (90-230 VAC /
50-60 Hz)
Mechanical:
Size: 1.75”H x 8.5”W x 5.5”D
Rack Spaces: 1/2 Space
Weight: 2.0 1bs. (0.91 kg)

DISASSEMBLY PROCEDURES
1. REMOVAL OF TOP COVER / FRONT PANEL (Fig1)
(A) TAKE OUT THE 4PC SCREWS FROM WHICH
THE TOP PANEL.
Fig.1
2. REMOVAL OF MAIN P.C.B (Fig2)
(A) REMOVE THE 4 PCSNUT OF 1/4”CONNECTORS REAR PANEL.
(B) REMOVE CABLE CONNECTOR FROM PCB
Fig.2

DISASSEMBLY PROCEDURES
3.REMOVAL OF FRONT PAREL P.C.B (Fig.3)
(A.) REMOVE THE 1PC OF SUB-PANEL.
Fig.3

WIRING DIAGRAM
(US/EU/UK/AUS NZ)

PACKING DIAGRAM
(US/EU/UK/AUS NZ)

EXPLODE DIAGRAM
(US/EU/UK/AUS NZ)
SEQUENCIAL NO OF EXPLODE DIAGRAM WILL BE MARKED ON REF. COLUMM OF BOM LIST

LEVEL P/N DESCRIPTION QTY REF
17-53-0228 STICKER COMPLIANCE ME1 1 14
1LAP67YAH255 STICKER 2
1PDEQ224ALE01 PACKING ASSEMBLY 1
2BASJ5012B FOOT ROUND LARGE 4
27-80-0310 ENDCAP CARDBOARD/PRESSBOARD 2
27-80-0361-A SPACER CARDBOARD PACKING ME1 1
27-80-0341 GIFT BOX 1
27-80-0360-A BOX SHIPPING (5-SETS) ME1 0.2
2PE060930BO PLASTIC BAG 2
27-90-0609 PLASTIC BAG 0.014
27-93-0910 BAG FORAM 9.5"x10.6" 1
25-00-0149 SCREW 2
27-51-0136 MANUAL REFERENCE 1
27-51-1219 SHEET "WELCOME TO ALESIS FAMILY" 5 x 8" 1
27-80-0341 GIFT BOX ME4 1
27-91-1002 GEL SILICA 5G PACKET 1
19-11-0039 CASE FRONT-PANEL ME1 1 4
19-23-0022-A SPACER RUBBER PCB ME1 1 9
19-30-0024 KEYPAD RUBBER 1 12
19-30-0029-A KEYPAD RUBBER BAND-SELECT ME1 1 3
1SC0306RICI SCREW M3x6mm 4 1
14-18-1000 CABLE RIBBON DIL 10-PIN 100mm 1 13
17-40-0903 CAP SWITCH 5 x 5mm 1
17-50-0183 STICKER BARCODE S/N ME1 1 6
19-01-0062 CHASSIS 1 7
19-01-0063 TOP COVER 1 2
19-01-0064 SUBPANEL 1 10
19-10-0061 BEZEL DISPLAY 3.3 THICK CLEAR 1 5
1
TWPC01C07402
I/O PCB ASS'Y
1
8
2
PC01C074
I/O PCB
1
2
TWPC02C074B01
I/O PCB ASS'Y
1
33-04-0013 LED 1D782
2
9-79-0310
I/O PCB ASS'Y
1
31-56-0103 CERAMIC 0.01UF 15 C9,11~13,15,17~19,30,31,35,36,42,44,45
32-01-4403 DIODE 6D1,2,4~6,8
34-16-0002 JACK 1J5
3JW5206T JUMP WIRE 21 JW1~JW21
3MT0303201 HEAT SINK PLATE 1(U5)
3NUT01030IID NUT 1(U2)
30-15-0101 RESISTOR 100O 2R26,27
30-15-0113 RESISTOR 11K 8R3,4,8,9,15,16,22,23
30-15-0133 RESISTOR 13K 4R1,2,6,7
30-15-0182 RESISTOR 1K8 2R5,10
30-15-0331 RESISTOR 330O 8R25,28~34
30-15-0332 RESISTOR 3K3 2R17,24
30-15-0472 RESISTOR 4K7 4R11,12,18,19
30-15-0562 RESISTOR 5K6 4R13,14,20,21
3SC0308RBZI SCREW 2(U5)
3SC0308RIZI SCREW 1(U2)
31-08-0222 ELECT 22UF/16V 4C3,8,14,16
31-08-0228 ELECT 2200UF/16V 3C37,43,46
31-08-0333 ELECT 330UF/16V 3C4,40,41
31-55-0561 CAP 560PF NPO 12 C1,2,5,6,7,10,20,23,24,25,28,29
31-56-0151 CAP 150PF NPO 4C21,22,26,27
32-11-7805 IC LM7805C 2U2,5
32-71-0084 IC TL084 1U1
32-75-1101 IC AL1101 1U7
32-75-1201 IC AL1201 1U4
32-77-0095 IC AL3102 1U3
34-02-0007 JACK 4J1~J4
34-14-1000 10P CONNECTOR 1J6
1
9-79-0288
FUNCTION PCB
1
11
21-56-0103 CERAMIC 0.01UF 8C1~4,6~8,13
21-56-0104 CERAMIC 0.1UF 1C18
21-56-0474 CERAMIC 0.147UF 3C11,12,14
23-04-0013 LED 1D782
23-20-0009 GREEN LED 27 D7,20,33,46,59,72,85,98,111,124,137,150,163,176,189,202,215
,228,D241,254,267,280,293,306,314,317,318
23-20-0011 RED LED 3D313,315,316
23-20-0010 YELLOW LED 289
D1~6,8~19,21~32,34~45,47~58,60~71,73~84,86~97,99~110,11
2~123125~136,138~149,151~162,164~175,177~188,190~201,2
03~214,216~227,229~240,242~253,255~266,268~279,281~292
,294~305,307~312,319
29-15-0295 LED FRAME 4
20-17-0101 RESISTOR 4X100O 1/16W 3R1,2,19
DEQ224 BOM

20-17-0102 RESISTOR 4X1K 1/16W 5% 10 R9,10,11,12,15,16,20,21,22,36
20-17-0151 RESISTOR 4X150O 1/16W 4R3,4,5,6
20-17-0470 RESISTOR 4X47 1/16W 7R23,24,25,26,27,28,30
21-60-3222 ELECT 22UF/16V(SMD) 1C17
22-51-4401 TRANSISTOR 2N4401 28 Q16,17,25~32,37~40,49~56,66~71
22-51-4403 TRANSISTOR 2N443 15 Q1~15
22-62-0595 IC 74AHC595 6U2,4,5,6,8,11
22-69-2416 IC EEPROM 16K 1U10
24-20-1000 10P HEADER DIL (SMD) 2J3,4
24-20-1001 10P HEADER DIL (SMD) 1J1
26-02-0055 SWITCH TACT 30 S1~30
27-01-0037 CRYSTAL 24MHz 1M2
29-40-0288 FUNCTION PCB 1
29-61-0088 IC 1U1

ME1 QC Test Procedures V1.00
Purpose: Explains test procedures for ME1 (DEQ-224) for quality assurance
of sub-assembly electronic functionality and audio fidelity, and final
assembly functionality.
NOTE! These procedures DO NOT contain tests for safety/EMC compliance, or
structural, assembly, or packaging quality.
Original Document Type: Word 2000
Current Revision: 1.00 First production release version.
Revision History:
04/17/2002 0.01 Initial Revision. Before Final release, update
software version check.
Peter Maresh
04/25/2002 0.02 Added Check to make sure Known Good Front Panel has
been reset in Section 2. Added section numbers.
Peter Maresh
03/05/2003 1.00 Adapted from Revision 1.00 of ME2 QC Test
Procedures V1.00 – Approved for Mass Production QC
Taiho Yamada and Peter Maresh
Questions or Comments Contact
Peter Maresh
Design Engineer, Alesis Studio Electronics, Los Angeles
[email protected]
310-821-5000
Taiho Yamada
ME1 Project Manager, Alesis Studio Electronics, Los Angeles
[email protected]
310-821-5000

Contents
1) QC Test Overview......................................................3
2) Rear Panel Sub Assembly Test..........................................4
Items Required.........................................................4
Assembly...............................................................4
Power Test.............................................................4
Audio Fidelity Test....................................................6
3) Front Panel Sub Assembly Test.........................................7
Items Required.........................................................7
Assembly...............................................................7
Power Test.............................................................7
Functionality Test.....................................................8
4) Assembly QC..........................................................13
Before the cover is screwed on........................................13
After the cover has been screwed on...................................13
5) Final Assembly QC....................................................14
Items Required........................................................14
Assembly..............................................................14
Power Test............................................................14
Functionality Test....................................................15
6) Reset................................................................19
Items Required........................................................19
Reset.................................................................19

1) QC Test Overview
QC tests are performed at two primary stages, sub-assembly level, and final
assembly level. Although several of the procedures are repeated during
both stages, the sub-assembly level tests are designed to test all
functionality of the electronic sub-assemblies, while the final assembly
tests are designed to catch assembly errors. Between the sub-assembly and
final assembly tests, the unit should be inspected for mechanical assembly
quality. After the tests, the unit is Reset before being packaged.
Note that these tests are for the unit assembly. These tests do not
include packaging and shipping QC.
The structure of the tests is as follows:
Electronic Sub-Assemblies QC
Front Panel
Test Buttons for electrical connectivity
Test LED display for electrical connectivity
Test EEPROM for electrical connectivity
Rear Panel
Test Power
Test Audio Fidelity
Assembly QC
Specifics of this QC are to be supplied by manufacturer.
The unit should be inspected before the top panel is closed for
correct assembly. All screws, sub-panel assembly, cabling
should be inspected for completion and correctness.
Inspection for appearance and mechanical completion after the top
panel is closed for correct final assembly. All external
screws, nuts, washers, plastic finish, metal finish, and
silkscreen should be inspected for completion, quality and
correctness. There should be no scratches and the colors and
text should be verified against the latest design for both the
front and back of the unit.
Final Assembly QC
Test LED display for appearance
Test Switches for mechanical connectivity
Test Audio for Sub-Assembly connectivity
Test Power for Sub-Assembly connectivity
Reset System
System is Reset for final packaging.

2) Rear Panel Sub Assembly Test
Items Required
1 ME1 Rear Panel (DUT)
1 Known Good ME1 Front Panel Sub-Assembly (Front Panel)
This front panel should have been reset as described in Section 6
“RESET.”
1 P3 type Alesis Power Supply
1 Computer with AP test equipment, s1_210k software, and ME2 test
procedure installed in directory “C:\ME1\”.
2 Female XLR to ¼” TRS audio cable
2 Male XLR to ¼” TRS audio cable
1 10 pin DIL cable for Rear Panel to Front Panel connection.
Assembly
1) Connect one Female XLR to ¼” TRS audio cable from AP unit channel A
OUT to DUT channel A IN.
2) Connect one Female XLR to ¼” TRS audio cable from AP unit channel B
OUT to DUT channel B IN.
3) Connect one Male XLR to ¼” TRS audio cable from AP unit channel A IN
to DUT channel A OUT.
4) Connect one Male XLR to ¼” TRS audio cable from AP unit channel B IN
to DUT channel B OUT.
5) Connect 10 pin DIL cable from the Front Panel J6 to the DUT J1. Be
sure that the Pin 1 stripe on the cable is oriented correctly on both
sub-assemblies.
6) Boot the computer into DOS mode and go into directory “V:\ME2.” For
details on how to configure the test files, see “C:\ME2\README.TXT”.
Type “startup” to start the test program.
7) Sub Assembly is ready for testing. Continue with Power Test.
Power Test
1) Before applying power, visually inspect the DUT for major assembly
problems.
Verify that U5 has a metal heat-sink that has been properly
screwed tightly to the metal tab with heat conducting gel.
Verify that U2 has been installed correctly and that the metal
tab has been screwed to the ground plane and is making a good
connection to the ground plane.
Verify all Electrolytic capacitors for correct orientation.
C3, C8, C14, and C16. C40, C41, C4, C43, C46, and C37.
Verify power diodes (D1, D2, D4, D5, D6, D8) have been
installed in the correct orientation.
Problems with this inspection indicate that the DUT has FAILED.
Failure of this inspection indicates that the DUT cannot
continue further testing.

Rear Panel Sub Assembly Test CON’T
1) Plug the P3 type Alesis Power Supply into a power source and the
barrel jack into the DUT Power In jack.
Verify that the front panel LEDs show the normal power up
message, “DEQ224”.
Verify that the LEDs do not flicker and are of a consistent
brightness.
Problems with this inspection indicate that the rear panel is
not supplying the correct voltage to the Front Panel. Double
check that the 10 pin DIL cable has been installed correctly.
If this is not the problem, then the DUT has FAILED.
Failure of this test indicates that this sub-assembly cannot
continue further testing. Quickly check the ICs on the Front
Panel. If any are hot, or if there is any other indication
that the Front Panel may have been damaged (burning smell,
etc.), follow QC procedures to check the Front Panel, because
the faulty DUT power supply may have damaged the Known Good
Front Panel.
2) Unplug the power supply and continue with Audio Fidelity Test if DUT
has not failed.

Rear Panel Sub Assembly Test CON’T
Audio Fidelity Test
1) Press the CHANNEL/EXIT and BYPASS buttons on the Known Good ME1 Front
Panel Sub-Assembly and hold these buttons during Step 2. When started
in this manner, the unit will enter Factory Test Mode.
2) Plug the P3 type Alesis Power Supply into a power source and the
barrel jack into the DUT Power In jack.
Verify that the front panel LEDs show normal power up message,
“DEQ224”. After this message, “TEST” should display briefly on
the LEDs.
Problems with this inspection indicate that the unit has not
entered Factory Test Mode. Unplug the unit and repeat steps 1
and 2.
3) When in Factory Test Mode, the unit will bypass audio so that AP
tests can run. Press ENTER on the computer to start the test
sequence. It is NOT necessary to enter a serial number since one has
not been assigned to the sub-assembly at this stage. Select ALL
TESTS at the appropriate menu to run all AP tests. The menu system
should be self-explanatory and will guide the user through connection
checks. DISREGARD instructions to power-up the DUT, as the DUT has
already been powered, and is already in the correct Factory Test
Mode.
Verify that the tests run without displaying a “Test Failed”
message.
Problems with multiple test failures may be an indication of
faulty test connection. Repeat the tests if a problem was
found with the cabling. If all the cables have been connected
correctly, then the DUT has FAILED.
Failure of this test indicates that this sub-assembly cannot
continue further testing. Quickly check the ICs on the Front
Panel. If any are hot, or if there is any other indication
that the Front Panel may have been damaged, follow QC
procedures to check the Front Panel, because a faulty IC on the
DUT may have damaged the Known Good Front Panel.
4) Unplug the power supply to the DUT. Then unplug all other cabling to
the DUT. This is the end of the Rear Panel Sub-Assembly electrical
test.