








MPX 100
DIAGNOSTICS /TROUBLESHOOTING
FOR SERVICE MANUAL








Author: Jim Ciardelli
Date: 05/01/98
Rev: 0      
Date: 06/15/98
Rev: 1
























Contents:

Introduction:

This document contains the complete diagnostic tests and their descriptions for the Lexicon MPX 100.

Diagnostics Overview:

There are two diagnostic sets in the MPX 100, Power On Diagnostics and Extended Diagnostics. 

Power On Diagnostics:

When the MPX 100 powers up it will first run its Power On Diagnostics. First all of the Front Panel LED's will light for approximately 200ms. It will then run the following sequence of tests  (see table 1 below)  that will take less than 10 seconds on time. 


Test No.
Test
  Edit
Bypass
Store
 Tap
   1
ROM Checksum
  0
  0
  0
 1
   2
SRAM
  0
  0
  1
 0
   3
Lexichip 3 WCS
  0
  0
  1
 1
   4
Lexichip 3 Interrupt Timer
  0
  1
  0
 0
   5
Lexichip 3 Audio Data File
  0
  1
  0
 1
   8
EEPROM Checksum
  1
  0
  0
 0



Table 1.
During the execution of the Power On Diagnostics, the CPU will display a test code on the EDIT, BYPASS, STORE & TAP LED's as indicated in table 1 above. The diagram below is a general graphic of the front panel of the MPX 100 and shows where these LED's can be read for the tests codes.



When the Power On Diagnostics tests are completed, the display will briefly flash  the version of running software present in the MPX 100.

Diagnostic Failures 

If a test failure is encountered during Power on Diagnostics the MPX 100 will set itself into the following state.

1)  The test code failure will be displayed by the Front Panel Button LED's  
2)  The Clip Headroom Led's (red) will be lit to indicate a failure has occurred.
3)  The MPX 100 stops Power On Diagnostics.
4)  The audio outputs are muted, normal operation is stopped.

There are 3 ways to proceed once a failure has been identified 

1)  Pressing the BYPASS button will attempt to continue on with the next test of the Power On Diagnostics sequence. This is helpful in determining if their is more than one test failure. The MPX 100 will attempt to do this every time the BYPASS button is pressed. Caution, bypassing a failed test and proceeding to the next test may result in excessive speaker excursion and/or loss of user register data.

2)  Pressing the  STORE after a failure has occurred, will put the MPX 100 into the Extended Diagnostics Mode. This will allow a more through testing of the unit when repairing .

3)  If the TAP button is pressed after a failure has occurred, the MPX 100 will                                           run the test continuously. This is a looping function that allows the circuitry to be examined when testing it on a repair bench.

Below is an example of how to read the front panel of the MPX 100 when a failure is encountered by the Diagnostics. The error failure shown is error code 3 (0011). This indicates the  Lexichip 3 WCS Test has failed.



Power Up Diagnostics Test Descriptions

ROM Checksum Test (1)

This test verifies the ROM's checksum by sending it a byte size value that is stored in the last location of Bank 0. The test then adds the contents of the entire ROM including the Checksum byte. The result should equal zero (8 bit value).

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

    Edit    Bypass          Store    Tap
                0          0                   0         1

If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code, and the CPU will attempt continuously loop the test for troubleshooting purposes.  

If the BYPASS button is pressed, the failure is ignored and the next test will be executed. 

SRAM Test (2)

The SRAM Test is performed during the Power Up Diagnostics. It is a  destructive test. The entire contents of the SRAM is tested by first writing 00 hex (00000000 binary) to all of the memory locations, and then verified by reading back all of the memory locations. The test is repeated by writing /reading the following patterns: 55 hex (01010101 binary), AA hex (10101010 binary) & FF hex (11111111 binary).

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

	       Edit    Bypass          Store    Tap
		0          0                  1         0

If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code, and the CPU will attempt continuously loop the test for troubleshooting purposes. 

If the BYPASS button is pressed, the failure is ignored and the next test will be executed. 

Lexichip 3 WCS Test (3)


This test will check the program memory space (the WCS) of the Lexichip 3. The RAM's memory space is first filled with the value 55 hex (01010101 binary), then each memory location is read to see if it contains 55. This test is repeated with AA hex (10101010 binary), and then 0"s. Following this test an Address test is implemented to verify all the address lines are active. Finally, the memory is checked for 0's.

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

	    Edit    Bypass          Store    Tap
               0           0                  1         1

If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code.

If the BYPASS button is pressed, the failure is ignored and the next test will be executed. 

If the TAP button is pressed, the CPU will attempt to go into a mode where it can execute the test continuously.

Lexichip 3 Interrupt Timer Test (4)

The Interrupt Timer test will verify that the interrupt (INT/ signal ) is working and occurring at the proper intervals. The Lexichip 3 will provide MPX 100 with the interrupt (INT/) to the Z80's maskable interrupt line. The interrupt test will be run for a period of time which allows 20 interrupts to occur. A count of the interrupts is kept and compared for overshoot and undershoot. Greater than 21 interrupts means the interrupt is too short and less than 19 interrupts means it's too long. 

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

Edit    Bypass          Store    Tap
                     0          1                  0         0

If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code.

If the BYPASS button is pressed, the failure is ignored and the next test will be executed. 

If the TAP button is pressed, the CPU will attempt to go into a mode where it can execute the test continuously.

Lexichip 3 Audio Data File Test (5)
[DJS1]
The Audio Data File (ADF) is a fast synchronous 128-word SRAM that provides audio data buffering and storage for: external memory references, Serial I/O, and the Host-to-Lexichip data port. ADF locations also function as ARU Registers and as scratch pad memory. This test will verify that the Lexichip 3 Audio Data File is working properly.

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

		Edit    Bypass          Store    Tap
                     0          1                  0         1

If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code.

If the BYPASS button is pressed, the failure is ignored and the next test will be executed. 

If the TAP button is pressed, the CPU will attempt to go into a mode where it can execute the test continuously.
                                                                                                                                                       EXTENDED DIAGNOSTICS

The Extended Diagnostics and troubleshooting Tools are accessed by pressing & holding the BYPASS button while powering on the MPX 100. The button can be released when the L & R Level (green) LED's are lit. After the BYPASS button is released, the Binary LED's (EDIT, BYPASS, STORE & TAP) will display the current position of the VARIATION knob in binary and the Level (green) LED's will go off. 

For example, if the VARIATION knob was set to 5, the LED's would read the following:

		Edit    Bypass          Store    Tap
                     0          1                  0         1
                     |                                         |
                  MSB                                    LSB

When a test is selected, the STORE button must be pressed to execute it. If the test passed, the L & R Level (green) LED's will light. If the test failed, the L & R Clip (red) LED's will light.

The following table shows the tests that are available in the Extended Diagnostics. The Test number column represents the VARIATION knob position.:



Test
Number
Test Name
Binary
LED's
     1
 ROM Checksum
0 0 0 1
     2
 SRAM Test
0 0 1 0
     3
 Lexichip 3 WCS
0 0 1 1
     4
 Lexichip 3 Interrupt Timer
0 1 0 0
     5  
 Lexichip 3 Audio Data File
0 1 0 1
 *   6
 Encoder/Switch/LED
0 1 1 0
**  7
 ADC Pot
0 1 1 1
    8
 EEPROM
1 0 0 0
    9
 MIDI
1 0 0 1
  *  10
 LED (for troubleshooting)
1 0 1 0
     11
 Lexichip 3 External DRAM
1 0 1 1
     12
 Burn In Loop
1 1 0 0
     13
 Audio I/O
1 1 0 1
     14
 Exit Diagnostics
1 1 1 0
     15
 Initialize
1 1 1 1


		These tests reside in the Power On Diagnostics.
	
	*	This test requires operator interaction and judgment. 
		Doesn't generate any error messages.

	**	This test requires operator interaction and judgment. 	Generates 	an error message.


The following Table is a group of tests that can be run in a continuous loop by pressing the TAP button instead of the STORE button. This is helpful in hunting down a problem at the circuit level when troubleshooting the MPX 100.

Test
Number
Test Name
Binary
LED's
1
 ROM Checksum
0 0 0 1
2
 SRAM Test
0 0 1 0
3
 Lexichip 3 WCS
0 0 1 1
4
 Lexichip 3 Interrupt Timer
0 1 0 0
5
 Lexichip 3 Audio Data File
0 1 0 1
8
 EEPROM
1 0 0 0
9
 MIDI
1 0 0 1
11
 Lexichip 3 External DRAM
1 0 1 1

When a test is run continuously in this mode a pass/fail status will be displayed and updated on the headroom LED's each time the test is run. If the test passed, the L & R Level (green) LED's will light. If the test failed, the L & R Clip (red) LED's will light.

To stop the test from running continuously, press the STORE button.

ROM Checksum Test (1)

This is the same test that resides in the power up diagnostics. It was included in the Extended Diagnostics for troubleshooting purposes.

This test verifies the  ROM's checksum by sending it a byte size value that is stored in the last location of Bank 0. The test then adds the contents of the entire ROM including the Checksum byte. The result should equal zero (8 bit value).

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

    Edit    Bypass          Store    Tap
                0          0                   0         1

Pressing the STORE button will execute the test.

Pressing the TAP button will run the test continuously

To stop the test from running continuously, press the STORE button.

If a failure occurs, the Clip (red) headroom LED's will be turned on in  addition to the binary code, and the CPU will attempt continuously loop the test for troubleshooting purposes.  

If the BYPASS button is pressed, the failure is ignored and the next test will be executed. 

The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When the test is executed, all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light. 


SRAM Test (2)

The SRAM Test performed during the Extended Diagnostics is a non-destructive test. The non-destructive test will test one memory location at a time, saving the contents from the location being tested into a register, and then restoring the value when it's done. The entire contents of the SRAM is tested by writing 00 hex (00000000 binary), and verified by reading the same value back from each memory location. This test is repeated by writing /reading 55 hex (01010101 binary), AA hex (10101010 binary) & FF hex (11111111 binary).

This test was included in the Extended Diagnostics for troubleshooting purposes.

When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
                     0          0                  1         0

Pressing the STORE button will execute the test.

Pressing the TAP button will run the test continuously

To stop the test from running continuously, press the STORE button.

The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When the test is executed, all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.



Lexichip 3 WCS Test (3)   
This test will check the program memory space ( of the WCS ) in the Lexichip 3. The RAM's memory space is first filled with the value 55 hex (01010101 binary), then each memory location is read to see if it contains 55. This test is repeated with AA hex (10101010 binary), and then 0"s. Following this test an Address test is implemented to verify all the address lines are active. Finally, the memory is checked for 0's.

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

	    Edit    Bypass          Store    Tap
               0           0                  1         1

Pressing the STORE button will execute the test.

Pressing the TAP button will run the test continuously

To stop the test from running continuously, press the STORE button.

The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When the test is executed, all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.
Lexichip 3 Interrupt Timer Test (4) 

This will test the Interrupt Timer by verifying the interrupt (INT/ signal ) is working and occurring at the proper intervals. The Lexichip 3 will provide MPX 100 with the interrupt (INT/) to the Z80's maskiable interrupt line. The interrupt test will run for a period of time which allows 20 interrupts to occur. A count of the interrupts is kept and compared for overshoot and undershoot. Greater than 21 interrupts means the interrupt is too short and less than 19 interrupts means it's too long. 

Before the test is executed, a test code will be displayed on the Binary LED's. The code is:

Edit    Bypass          Store    Tap
                     0          1                  0         0
Pressing the STORE button will execute the test.

Pressing the TAP button will run the test continuously

To stop the test from running continuously, press the STORE button.

The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When the test is executed, all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.



Lexichip 3 Audio Data File Test (5)

This test will verify that the Lexichip 3 Audio Data File is working properly. The Audio Data File (ADF) is a fast synchronous 128-word SRAM that provides audio data buffering and storage for: external memory references, Serial I/O, and the Host-to-Lexichip data port. ADF locations also function as ARU Registers and as scratch pad memory.
When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
          	  0          1                  0         1

To run the test again, press the STORE button.

Pressing the TAP button will run the test continuously

To stop the test from running continuously, press the STORE button.

The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When the test is executed, all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.

Encoder/Switch/LED Test (6)

The Encoder/Switch/LED Test is essentially three tests in one. The combination of the three tests provide a means for verifying the operation of the Encoders (2), Front Panel Buttons (3) and Footswitches (2) at the same time.  

When selected, the display will read the following:

		Edit    Bypass          Store    Tap
                     0          1                  1         0

Pressing the STORE button will execute the test. 
When the test is executed, the Left Level (green) LED will be lit, and all Front Panel LED's will be turned off.

IMPORTANT: The Encoder/Switch/LED Test MUST be performed in the proper sequence. The Encoder portion of the test MUST be performed first, before any Switch or LED testing can be performed.

Encoders:

Note: When the test is executed the encoder must be rotated in a clockwise direction as it's being tested, or the test will fail. During the Encoder Test, the Front Panel Binary LED's will display the current position of the Encoder under test in binary. (See Table 2 below)


When the Encoder Test is first executed, the Left Level (green) LED will be lit to indicate that the VARIATION Encoder is being tested.

When the VARIATION Encoder has been varied over its entire range (clockwise), the Left Level (green) LED will be turned off to indicate the VARIATION Encoder has passed, and the Right Level (green) LED will be turned on. 

If the VARIATION Encoder fails, the Left Clip (red) LED will light. 

Once the VARIATION Encoder has passed, the Right Level (green) LED will be lit to indicate that the PROGRAM Encoder is being tested. 

When the PROGRAM Encoder has been varied over its entire range (clockwise), the Right Level (green) LED will be turned off to indicate that the PROGRAM Encoder has passed, and the Front Panel Switches and Footswitches are ready to be tested.

If the PROGRAM Encoder fails, the Right Clip (red) LED will light.

PROGRAM Encoder
Position 
VARIATION Encoder 
Position
Binary
LED's
  Plate, Gate
1
0 0 0 1
  Hall, Chamber
2
0 0 1 0
  Ambience, Room
3
0 0 1 1
  Tremelo, Rotary
4
0 1 0 0
  Chorus, Flange
5
0 1 0 1
  Pitch, Detune
6
0 1 1 0
  Delay, Echo
7
0 1 1 1
  Special FX
8
1 0 0 0
  User
9
1 0 0 1
  Flange - Delay
10
1 0 1 0
  Pitch - Delay
11
1 0 1 1
  Chorus - Delay
12
1 1 0 0
  Delay - Reverb
13
1 1 0 1
  Flange - Reverb
14
1 1 1 0
  Pitch - Reverb
15
1 1 1 1
  Chorus - Reverb
16
0 0 0 0
Table 2.

Footswitches:
For this test you will need a Dual-function footswitch similar to the one stated in the owners manual on page 5.

When the left footswitch (labeled Ring) is pressed, the left Level (green) LED will light. The remaining LED's will be off. When the left footswitch is released, the left Level (green) LED will go off and the remaining LED's will be off as well.

When the right footswitch (labeled Tip) is pressed, the right Level (green) LED will light. The remaining LED's will be off. When the right footswitch is released, the right Level (green) LED will go off and the remaining LED's will be off as well.

To test the front panel switches proceed to the next section 

If you wish to exit the test at this time, press and hold the STORE button for a few seconds then release. The binary LED's will then display the current position of the VARIATION Encoder.


Front Panel Switches:

When the BYPASS button gets pressed, its LED will light and the remaining LEDs will go off. When the BYPASS button is released, its LED will go off and the remaining LEDs will be off as well.

When the TAP button gets pressed, its LED will light and the remaining LEDs will be off. When the TAP button is released, its LED will go off and the remaining LEDs will be off as well.

When the STORE button gets pressed, its LED will light and the remaining LEDs will be off. When the STORE button is released, its LED will go off and the test will be exited. 

Encoder Gray Scale

The following table is provided as a reference for debugging encoder problems. 

Encoder Position

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16
Pin 1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
Pin 2
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
Pin 3
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
Pin 4
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
Pin 5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Table 3.

Note: The logic levels from the encoders are only valid when the enable (pin 5) is low. 

ADC Pot Test (7)
The MIX, EFFECTS LVL/BAL and ADJUST Pots are connected to integrating type ADC's (A/D Converters) and are read digitally by the Lexichip 3. The ADC Pot Test will verify that the pots and converters are working.

While performing the ADC Pot Test, the ADC Pot under test must be varied over its entire range from fully counter-clockwise to fully clockwise and back to fully counter-clockwise (CCW-CW-CCW). 

During the rotation of the ADC Pot under test, the data generated by the ADC circuitry during the sweep will be analyzed and confirm that the circuit is accurately reporting the data to the Lexichip 3. When the (CCW-CW-CCW) sweep has been completed successfully, the test will display a Pass, Fail or Timeout status on the headroom (L & R Level & Clip (red) LED's).  

When an ADC Pot is being tested, the ADC Pot must be swept over its entire (CCW-CW-CCW) range within five seconds. Otherwise, after 5 seconds the headroom LED's will indicate that a Time-out Failure has occurred.

When selected, the Front Panel LED's will read the following:

		Edit    Bypass          Store    Tap
                     0          1                  1         1

Pressing the STORE button will execute the test. 

When the test is executed the remaining buttons, encoders, ADC Pots and footswitches (2) are inactive, and all Front Panel LED's will go off. 

The STORE button will be active to exit the test.


MIX Pot Pass/Fail Status:

The Left Level (green) LED will be lit to indicate when the MIX Pot is being tested. The remaining LED's will be off.

If the MIX Pot passes the test, the Left Level (green) LED will flash about 2 times per second. 

If the MIX Pot fails the test, the Left Clip (red) LED will flash about 2 times per second. 

If the MIX Pot exhibits a time-out failure, the Left Level & Clip (red) LED's will flash about 2 times per second. 


EFFECTS LVL/BAL Pot Pass/Fail Status:

The Right Level (green) LED will be lit to indicate when the EFFECTS LVL/BAL Pot is being tested. The remaining LED's will be off.

If the EFFECTS LVL/BAL Pot passes the test, the Right Level (green) LED will flash about 2 times per second. 

If the EFFECTS LVL/BAL Pot fails the test, the Right Clip (red) LED will flash about 2 times per second. 

If the EFFECTS LVL/BAL Pot exhibits a time-out failure, the Right Level & Clip (red) LED's will flash about 2 times per second. 


ADJUST Pot Pass/Fail Status:

The L & R Level (green) LED's will be lit to indicate when the ADJUST Pot is being tested. The remaining LED's will be off.

If the ADJUST Pot passes the test, the L & R Level (green) LED's will flash about 2 times per second. 

If the ADJUST Pot fails the test, the L & R Clip (red) LED's will flash about 2 times per second. 

If the ADJUST Pot exhibits a time-out failure, the L & R Level and L & R Clip (red) LED's will flash about 2 times per second. 

After the MIX, EFFECTS LVL/BAL and ADJUST pots have all been tested, the headroom LED's will display the pass/fail status of the test. 

The L & R Level (green) LED's will be lit to indicate the test has passed, or the L & R Clip (red) LED's will be lit to indicate the test has failed.

EEPROM Checksum (8)

This test will read each byte in the User Register portion of the EEPROM and adds them together to calculate a checksum. This value is compared with the checksum value stored in the EEPROM itself. This checksum will be recalculated each time a register is stored.

When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
                     1          0                  0         0

Pressing the STORE button will execute the test. 

When the test is executed the remaining buttons, encoders, ADC Pots and footswitchies (2) are inactive, and all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.

To run the test again, press the STORE button.

To run the test continuously, press the TAP button. 

To stop the test from running continuously, press the STORE button.
MIDI Tests (9)

MIDI Out To MIDI In

This test will verify that the MIDI Input and MIDI Output/Thru  circuits are working. The test will transmit data out of the MIDI OUT jack and will attempt to read the data through the MIDI IN jack. To run this test, a 5 Pin Male DIN to 5 Pin Male DIN Cable (also known as a MIDI cable) must be connected between the MIDI IN jack and the MIDI OUT jack. MIDI Input and MIDI Output/Thru comes from the Lexichip 3.

When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
                     1          0                  0         1

Pressing the STORE button will execute the test. 

When the test is executed the remaining buttons, encoders, ADC Pots and footswitches (2) are inactive, and all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.

To run the test again, press the STORE button.

To run the test continuously, press the TAP button. 

To stop the test from running continuously, press the STORE button.


MIDI Thru To MIDI In

The MIDI Thru circuitry is tested during the ATE testing at the factory. A MIDI command is sent to the MPX 100 which sets the MIDI Out/MIDI Thru to MIDI Thru. The default setting for the MIDI Out/MIDI Thru is MIDI Out. 

A DOS command was developed by Lexicon: APUTIL M. The APUTIL M T command is a self contained test for MIDI THRU and wrap around (for information on APUTIL, refer to document 010-09629). The MIDI OUT cable from the Audio Precision's PC (MPU-401 Card) will be connected to the MIDI IN connector on the MPX 100. The MIDI IN cable from the Audio Precision's PC will be connected to the MIDI OUT/MIDI THRU connector on the MPX 100.

When the APUTIL M T command is executed, the MIDI Output from the PC will produce a message (F8 for example) in which the message will get reproduced at the MPX 100's MIDI THRU jack. The PC will read and verify the message was received from the MPX 100's MIDI THRU jack. The test can be easily be run by entering the command APUTIL M T F8 (or any other byte except for FF) in the Audio Precision's DOS mode or from the PC's command line. 

The test programs and utilities are available, unsupported, for service centers using the Audio Precision brand test equipment set. Contact Lexicon Customer Service.
LED Test (10)

This test will verify all LED's (8) are working. When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
                     1          0                  1         0

Pressing the STORE button will execute the test. 

When the test is executed, the Front Panel LED's that are assigned to the current position of the PROGRAM Encoder will be lit. (See below)

PROGRAM Encoder
Position
LED Assignment 
  Plate, Gate
  All LED's On
  Hall, Chamber
  Left Clip On
  Ambience, Room
  Right Clip On
  Tremelo, Rotary
  Left Level On
  Chorus, Flange
  Right Level On
  Pitch, Detune
  Edit On
  Delay, Echo
  Bypass On
  Special FX
  Store On
  User
  Tap On
  Flange - Delay
  All LED's Off
  Pitch - Delay
  All LED's Off
  Chorus - Delay
  All LED's Off
  Delay - Reverb
  All LED's Off
  Flange - Reverb
  All LED's Off
  Pitch - Reverb
  All LED's Off
  Chorus - Reverb
  All LED's Off


The STORE button will be active to exit the test. The PROGRAM Encoder will be active to test the LED's. Referring to Table 2, each LED is assigned to a position on the PROGRAM Encoder. When a position is selected, its assigned LED will light. There's also a position where all the LED's will light and a position where all LED's are off. 

When the test is executed the VARIATION Encoder, BYPASS, TAP, ADC Pots and footswitches (2) are inactive.

Lexichip 3 External DRAM Test (11)

This test puts the Lexichip 3 (U5) into a mode that allows the Z80 processor (U7) to read and write to the 1M X 4 DRAM (U3) through the Lexichip 3. To actually test the DRAM, the Z80 processor performs two tests: a data test and an address test. During the data test the Z80 processor writes "AA" (hex) (10101010) into all of the memory locations then reads them back to check them. It repeats the process with "55" (01010101). For the address test, the Z80 processor writes a count into the memory then reads it back (i.e.00000001, 00000010, 00000011). 

When selected, the Binary LED's will read the following:

	Edit    Bypass          Store    Tap
  1          0                  1         1

Pressing the STORE button will execute the test. 

When the test is executed the remaining buttons, encoders, ADC Pots, and footswitches (2) are inactive, and all Front Panel LED's will go off. 

If the test passed, the L & R Level (green) LED's will light.

If the test failed, the L & R Clip (red) LED's will light.

To run the test again, press the STORE button.

To run the test continuously, press the TAP button. 

To stop the test from running continuously, press the STORE button.

Burn In Loop (12)

The Burn In Loop will continuously run the following diagnostics:

Test
Number
Test Name
Binary
LED's
1
 ROM Checksum
0 0 0 1
2
 SRAM Test
0 0 1 0
3
 Lexichip 3 WCS
0 0 1 1
4
 Lexichip 3 Interrupt Timer
0 1 0 0
5
 Lexichip 3 Audio Data File
0 1 0 1
11
 Lexichip 3 External DRAM
1 0 1 1


When selected, the Binary LED's will read the following:

	Edit    Bypass          Store    Tap
  1          1                   0         0

Pressing the STORE button will execute the test. 

When the test is executed the remaining buttons, encoders, ADC Pots and footswitches (2) are inactive.

During the execution of the Diagnostics in the Burn In loop, the appropriate test code will be displayed on the binary LED's. This code will be sent to the LED's before each test is executed. By displaying a test/error code on the LED's before the test is activated, it will be easier to determine which test failed if the unit hangs or crashes during the Burn In Loop.

If a test failed, the Burn In Loop will stop and the Binary LED's will display which test failed along with the L & R Clip (red) LED's lit.

There are three options available when a test has failed during the Burn In Loop:

1.	Press the BYPASS button to continue the Burn In Loop

2.	Press the TAP button to run the test continuously.

3.	Press the STORE button to exit the Burn In Loop.

Audio I/O (13)

The Audio I/O Test will set the audio path through the MPX 100 for 100% wet SIGNAL without any effects. The audio DRAM is used during this test. By using this test, the technician can eliminate major functional sections of the system when troubleshooting distortion noise, gain, crosswalk and frequency response problems in a system. 

When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
                     1          1                  0         1

Pressing the STORE button will execute the test. 
When the test is executed the L & R Level (green) LED's are lit, and the test number is displayed on the Binary LED's. The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive.

Exit Diagnostics (14)

This selection will allow the user to exit the Extended Diagnostic Mode into normal operating mode. When selected, the Binary LED's will read the following:

		Edit    Bypass          Store    Tap
                     1          1                  1         0

Pressing the STORE button will execute the test. 

When the selection is executed the remaining buttons, encoders, ADC Pots and footswitches (2) are inactive, and the MPX 100 will exit Extended Diagnostic Mode and enter normal operating mode. 
Initialize (15) 
This selection will initialize the MPX 100 and reset the parameters to factory defaults.

Note: Performing this test will clear any registers store in the MPX 100. To save them they must be down loaded before this test is executed. Once the test is done they can be reloaded.

When selected, the Binary LED's will read the following:

  		Edit    Bypass          Store    Tap
                     1          1                  1         1

Pressing the STORE button will execute the test. 

The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When this selection is executed, the MPX 100 will reset, perform its power on sequence and enter normal operating mode. 

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[DJS1]Need description of Lexichip ADF test from Programmer

3 Oak Park, Bedford, MA 01730  Tel (781) 280-0300, Fax (781) 280-0499
email: csupport@lexicon.com

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