Lexicon 200, Service Manual

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MPX 200 Service Manual
5-4
If the Tap/Cancel button is pressed, the CPU will attempt to go into a mode where it can execute the test
continuously.
EEPROM Test (6)
This test will read each byte in the User Register portion of the EEPROM and add 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.
The test will also verify that the EEPROM has been initialized properly. This is done by storing the software
version of the EEPROM in the first five bytes of the EEPROM, and then verifying the stored value is correct
when the test is executed. If the stored value read from the first five bytes of the EEPROM is incorrect, the
EEPROM will be initialized.
Before the test is executed, the following test code will be displayed on the Diagnostic LEDs:
Test # Test Name Diagnostic LED
6 EEPROM EFFECTS “Gate“
If a failure occurs, the (Red) LEVEL LEDs will be turned on in addition to the Diagnostic LED, and the CPU
will attempt to continuously loop the test for troubleshooting purposes.
If the Bypass button is pressed, the failure is ignored and the next test will be executed.
If the Tap/Cancel button is pressed, the CPU will attempt to go into a mode where it can execute the test
continuously.
NOTE: The first time the MPX 200 is powered on when a new EEPROM part has been installed or the
Software version has changed and the EEPROM is initialized, the EEPROM will be initialized
during the EEPROM diagnostic test and the 7-segment display will display “rSt” to indicate that the
EEPROM is being initialized. Once the EEPROM has been initialized, the unit will reset and repeat
the POST. This initialization process takes approximately 40 seconds, otherwise the POST would
normally take approximately 10 seconds.