Lexicon MC-1, Руководство по обслуживанию

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MC-1 Service Manual
4-4
RECORD, VCR: 53 RECORED, DVD: 52 RECORD, V-DISC: 51 RECORD, TV: 50
RECORD, AUX: 4F RECORD, CD: 4E RECORD, TUNER: 4D RECORD, TAPE: 4C
Main Audio Output Test
Setup
1. Attach the audio input cable between the Low Distortion Oscillator and the MC-1 Left VCR input.
2. Attach the audio output cable between the MC-1 Left Front output and the input of the Distortion
Analyzer.
3. Put the MC-1 into Extended Diagnostics mode by powering up the MC-1 while pressing and holding
down both the front panel REC/ZONE2 and EFFECT buttons until Extended Diagnostics appears on
the display.
4. Press the TAPE button on the remote. The display will read AUDIO Test.
5. Press and hold the Shift button on the remote, then press the On button. The #98 will then be displayed
next to AUDIO Test. This indicates that the VCR input to Plain Analog outputs path has been enabled.
Tests
1. Apply a 1kHz signal @ +12dB (+4 Vrms) to the input channel.
2. Set the scale on the Distortion Analyzer to m12dBV (+ 4Vrms ) signal level.
3. Turn all filters off on the Analyzer.
4. Verify that the output level from the MC-1 is +12dBV (+4Vrms) +0.2/-0.3dBV.
5. Adjust the scale on the Distortion Analyzer to measure 0.005% THD+N and turn on the 30kHz low pass
or audio bandpass filter.
6. Verify that the THD+N measured is less than 0.005%
7. Set the scale on the Distortion Analyzer to m12dBV (+ 4Vrms) signal level.
8. Use the output level from Step 4 above for a 0dB reference to check frequency response.
9. Turn the filter off. Next sweep the oscillator frequency from 10Hz to 20kHz.
10. Verify that the signal level is 0.2/-0.3dB of reference level over the frequency band.
11. Set the scale on the Distortion Analyzer to measure –100dBr signal level with the filter on. Turn off the
oscillator to the MC-1 and verify a noise level measurement less than -105dBr.
12. Swap the Left Front output cable to the Right Front output.
13. Repeat steps 1 to 11 above.
14. Test the remaining Main outputs of the MC-1 being sure to repeat steps 1 to 11 for each.
Digital Input to Analog Output Tests
This test verifies that all 8 digital inputs to an analog output of the MC-1 are functioning properly. It is
important that all previous tests from this section be preformed prior to this test.
Setup
1. Connect the coaxial digital source to the MC-1 Coax 1 input.
2. Connect the MC-1’s Left and Right Front audio outputs to the amplifier Left and Right inputs, and turn
down the volume level control on the amplifier.
3. Place the MC-1 into Extended Diagnostics mode by applying power to the MC-1 while pressing and
holding down both the REC/ZONE2 and EFFECT buttons on the front panel until Extended Diagnostics
appears on the display.
4. Press the TAPE button on the remote to select the AUDIO Test.
5. Press and hold down the SHIFT button, then press the CD button to select a digital input source. The
display should read: AUDIO Test 8E.
6. Press the Dolby Digital button on the remote to select Coax 1 digital input for testing. The #20 will be
displayed to indicate the Digital Coax 1 to output test path has been set.