Chapter 4 Performance Verification; Diagnostics; Setup; I/O Tests - Lexicon MPX 500 Service Manual

Chapter 4 Perfo r mance Verification
This section describes a quick verification of the operation of the MPX 500 and the integrity of its analog
and digital audio signal paths.

Diagnostics:

The MXP 500 contains two types of Diagnostics: Power Up Diagnostics, and Extended Diagnostics. Each
of these will be described fully in Chapter 5: Troubleshooting. When the MPX 500 is powered on, the Power
up Diagnostics run automatically to verify proper operation of its internal systems. The Power Up
Diagnostics consist of the following tests:
ROM Test
SRAM Test
WCS Test
INT Test
ADF Test
EEPROM Test

Setup:

1. Turn on the MPX 500 and wait for the Power Up Diagnostics cycle to finish.
2. Enter System Mode by pressing the System button.
3. Use Edit Knob 1 to select the following System Parameters and Edit Knob 3 to set the parameter as
noted:
3.1. Output Level: 0dB
3.2. Input Source: Analog Stereo
3.3. Clock Source: Internal 44.1k
3.4. Bypass Mode: Dry
4. Press the System button to return to the previous running mode.
5. Turn the Program Select Knob to Program #1.
6. Press the Bypass button on the front panel and verify that the button LED lights.
7. Connect a (balanced) audio cable between the Low Distortion Oscillator and the MPX 500 Left Input.
8. Connect a (balanced) audio cable between the MPX 500 Left output and the Distortion Analyzer.
9. Set the Distortion Analyzer to measure Vrms.
10. Turn the Input Trim knob fully clockwise.

I/O Tests:

These tests will verify the audio performance of the MPX 500's audio input and output circuitry

Analog In To Analog Out Level Test:

1. Apply a 1kHz sinewave signal to the MPX 500 Left Input @ 1.946Vrms.
2. Adjust the Input Trim knob and measure the output for a level between 15.46 and 13.78Vrms.
3. Move the cables to the Right Input/Output connections and repeat step 2.

Frequency Response Test:

These tests will verify the frequency response specifications of the Left and Right analog inputs to the Left
and Right analog output signal paths of the MPX 500.

Analog In To Analog Out Frequency Test:

1. Disable all Filters on the Distortion Analyzer
2. Apply a 1kHz sinewave signal to the MPX 500 Left Input @ 3.083Vrms
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