Lexicon 200, Service Manual

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Lexicon
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3. Connect the Right Output to the Distortion Analyzer.
4. Enable the Low pass filters on the Analyzer (30kHz, 20kHz).
5. Sweep the Oscillator from 20Hz to 20kHz and verify the level stays < -55dBu through out the sweep.
6. Switch the Input cable and plug and switch the Output cable to the Left and repeat the test.
Dynamic Range Test
These tests will verify the Dynamic Range specifications of the MPX 200 Left and Right input to output
circuitry.
Analog In To Analog Out Dynamic Range Test
1. Apply a 1kHz-sinewave signal to the MPX 200 Left and Right Inputs @ 775 mVRMS (0dBu).
2. Connect the Left Output to the Distortion Analyzer.
3. Set the Distortion Analyzer for a 0dB reference.
4. Remove the Left Input signal.
5. Enable the Low pass filters on the Analyzer (30kHz, 20kHz).
6. Verify the Noise level at the Left Output is < -95dBr.
7. Move the cable from the Left Output to the Right Output.
8. Set the Distortion Analyzer for a 0dB reference (be sure signal is applied to the Right Input).
9. Remove the Right input signal.
10. Enable the Low pass filters on the Analyzer (30kHz, 20kHz).
11. Verify the Noise level at the Right Output is < -95dBr.
Digital I/O Functionality
This test will verify that the MPX 200 will pass an S/PDIF signal through its input and output circuitry.
1. Connect a Digital signal (CD player, DAT, etc.) to the S/PDIF input jack on the back of the MPX 200.
2. Connect the S/PDIF output for the MPX 200 to a D/A converter (ex.: MPX 500) for conversion back to
an analog signal.
3. Connect the analog output of the D/A converter to your amplifier with speaker output. Be sure to turn
the volume down on the amplifier.
4. Set the MPX 200 System Mode for digital Input.
5. Set the D/A converter for digital Input.
6. Start playing your digital source.
7. Turn the volume up on your amplifier and verify you have audio and that it is clean and free of any
audio defects or artifacts (pops, clicks, static, etc.).
Listening Test
1. Connect the audio input cables from the output of the Low Distortion Oscillator to the Left and Right
Inputs of the MPX 200.
2. Connect the audio output cables from the Left and Right Outputs of the MPX 200 to the input of the
Headphone amplifier.
3. Set the Headphone Amplifier volume control to its lowest setting.
4. Set the Oscillator for 220Hz sinewave at 50m Vrms (-24dBu).
5. Power on the MPX 200 and turn the program knob to the # 111 program: Abyss.
6. Press the Edit button and turn the Mix up to 100%.
7. Put on the headphones and bring the volume up on the Headphone amp to a comfortable listening
level.
8. Sweep the input knob over its entire range and verify there are no pops, clicks, distortion, or static
noises heard when turning the knob.
Shock Test
Note: To prevent damaging the unit, keep the other sides of the unit touching the work surface at all times.