NAIM Audio NAIT 5si (not 5i) Integrated Amplifier - Schematic wanted

This amp from a friend sounds good - go to
https://www.stereophile.com/content/naim-audio-nait-5si-integrated-amplifier-measurements
But sometimes (not often) right channel sounds with heavy reduced level and increased distortion on all inputs (unfortunately not sensitive to vibration and temperature variation).

PCB is mainly equipped with SMD parts (except power devices, the big BHC elcaps behind the rectifiers and any few others).
Without circuit diagram troubleshooting is too difficult and sending to Naim Audio will be very expensive due replace the complete main board there.

Who can upload the schematics ?
Thanks for your effort.

P.S.: this thread don't provide the wanted information:
https://www.diyaudio.com/community/threads/naim-nait-5i.322055/
 

Attachments

  • hfm11_3002.jpg
    hfm11_3002.jpg
    81.1 KB · Views: 322
  • hfm11_3001.jpg
    hfm11_3001.jpg
    84.1 KB · Views: 404
  • naim-nait-5si_inside_1_.jpg
    naim-nait-5si_inside_1_.jpg
    240.7 KB · Views: 410
  • hfm11_3006.jpg
    hfm11_3006.jpg
    138.9 KB · Views: 441
  • Naim_NAIT_5SI_integralt_erosito_4.jpg
    Naim_NAIT_5SI_integralt_erosito_4.jpg
    135.2 KB · Views: 386
  • post-1956-0-26179900-1511373251 (1).jpg
    post-1956-0-26179900-1511373251 (1).jpg
    133.3 KB · Views: 1,013
  • 25725-max_naim_nait_5si_3.jpg
    25725-max_naim_nait_5si_3.jpg
    101.6 KB · Views: 473
  • 1014NAITfig08.jpg
    1014NAITfig08.jpg
    27.2 KB · Views: 372
Last edited:
You may have noticed that the large electrolytic cap. brands and grades have changed (Kemet V BHC) and apparently, so has the transformer in the 5si. Overall, there must have been enough changes to issue another revision from the first improvement (5i) to the second (5si). There have probably been other minor parts spec. revisions and even the peak output power, as I understand.