Lexicon 200, Service Manual

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MPX 200 Service Manual
5-2
Pass/Fail Status
The front panel LEVEL LEDs are used to indicate the pass/fail status of the POST as follows:
The (Green) LEVEL LEDs are lit to indicate when the test has Passed.
The (Red) LEVEL LEDs are lit to indicate when the test has Failed.
Diagnostic Failures
When a failure is encountered during the test sequence:
The test code is displayed on the Diagnostic LEDs (Refer to Table 1).
The (Red) LEVEL LEDs are turned on to indicate a failure has occurred.
The unit stops executing the POST sequence.
The audio outputs are muted, and the unit will not become operational.
If the Bypass button is pressed after a failure has occurred, the MPX 200 will attempt to continue on with
the next test of the POST sequence. The MPX 200 will attempt to do this every time the Bypass button is
pressed.
If the STORE button is pressed after a failure has occurred, the MPX 200 will enter the Extended
Diagnostics mode.
If the Tap/Cancel button is pressed after a failure has occurred, the MPX 200 will run the test continuously.
The following diagram shows an example of the Diagnostic LEDs Test/Error code 4. This code indicates
that the
Lexichip3 INT
Test (4) has failed:
LEVEL COMPRESSOR
L R 1 Threshold <-
indicates Lexichip3 INT test
Indicates Error ->
1 1 0 -3dB
0 0 0 -10dB 0 Gate
0 0 0 -20dB 0 Echo/Delay
Legend: 0 = LED off, 1 = LED on
NOTE: During the POST, the LEVEL LEDs display the pass/fail status for tests 3-6 only.
Power On Test Descriptions
ROM Test (1)
The ROM checksum, is a byte size value that is stored in the last location of each bank. The test adds the
contents of the entire ROM including the checksum byte. The result should equal zero (8 bit value).
Before the test is executed, the following test code will be displayed on the Diagnostic LEDs:
Test # Test Name Diagnostic LED
1 ROM COMPRESSOR “–20dB”
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.