NAD S400
Service Manual

NAD S400

NOTE: Return to step #3 and perform the same alignment procedure but substitute L2 for L1. Continue to align L10, L7, L2, and L1, until there is no improvement in IF-level maximum level between the two antenna ports, and that the isolation between the two ports is greater that 40 dB. Alignment of IF Section: 6)

Connect an RF signal generator to ANTENNA port #1 and set to: Amplitude = 45 dBu Pilot tone = off Modulation = off Frequency = 98.000 MHz. Press the ANTENNA-button and select ANTENNA port #1. Press the IF-button to select IF WIDE. With the same oscilloscope setup as in procedure #3, check that the IF-signal had increased approximately 3 dB compared to IF NARROW. Remove the oscilloscope probe from the common point between CF3 and CF4.

Adjust L13 (or VR1) until the centre-tune LED turns on. Fine adjust VR1 so that it lights from approximately 97,965 MHz. to 98,035 MHz equally. Alignment of Audio Section: 8) Set the S400 as the following: Press the IF-button to select IF WIDE. Press the ANTENNA-button and select ANTENNA 1. Press the MONO/MUTE-button to MUTE OFF MONO. Press the BLEND-button to BLEND OFF. Press the BANDWIDTH-button to BANDWIDTH WIDE. Tune the S400 to 98.00 MHz. Connect an audio AC voltmeter with decibel display to both the right and left audio output jacks. Set the AC-voltmeter to negative 30 dB range. Leave the audio AC-voltmeter attached to the S400 audio output jacks until told to remove it. Then connect an RF signal generator to ANTENNA port #1 and set to: Amplitude = 45 dBu Pilot tone = on (19 kHz @ 10%) Modulation = off Frequency = 98,00 MHz Adjust L3 for a minimum 19 kHz output at the right audio jack. Adjust L4 for a minimum 19 kHz output at the left audio jack

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Connect an RF signal generator to ANTENNA port #1 and set to: Amplitude = 70 dBu Pilot tone = off Modulation = off Frequency = 98.000 MHz.

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With the same oscilloscope setup as in procedure #3, press the ANTENNA button and select ANTENNA port #1. Check that the IF-signal is reduced by a minimum of 40 dB. Connect the signal generator to ANTENNA port #1. With the same oscilloscope setup as in procedure #3, adjust L2 until the IF-signal is at maximum setting. Press the ANTENNA button and select ANTENNA port #2. Check that the IF-signal is reduced by a minimum of 40 dB.