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907 imos limited ....Need to know bias values and service manual

Discussion in 'Exclusively Sansui' started by quadklipsh, Mar 24, 2018.

  1. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    Hi all .

    My tech wants me to find out the manual for the sansui 907 imos limited ....
     

     

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  2. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    like i mentioned earlier the amp doesnot sound right . so there has GOT to be something amiss, and the tech that opened up my amplifier 2 years ago said he didnot have the biasing corrected because of NO manual .
    i have a strong feeling that this could be the main reason for the amp to be sounding less attractive than the others
     
  3. Shavalievdd1

    Shavalievdd1 New Member

    Messages:
    26
    My bias setting is 25-28 mV

    read this tread http://www.audiokarma.org/forums/in...au-alpha907-limited-in-da-house.665516/page-5
     
  4. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    But my amp is the black one.

    Its the AU alpha 907 imos limited.
     
  5. Shavalievdd1

    Shavalievdd1 New Member

    Messages:
    26
    i have same amplifier and told you my settings

    you wont find the service manual here as this is very rare document. read above thread as it contains useful information and some screenshots from the manuals.
     
  6. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    Thanks shavaliedd1 ,
    Ofcourse thats a treasure youve shared .
    Ill keep it for my repairs n references of the 907.

    Apart from this , hiw well is this amp serving you . May i know ur setup . And how do you recommend it for best performance ..
    I sold this amp 2 yrs ago and the owner hasnt used it at all and is in Russia for university.
    1q
     

     

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  7. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    But i got it back from him for a spin . Coz hes gonna be back in 4 months... To pakistan .

    May i i know your location n setup please.
     
  8. Shavalievdd1

    Shavalievdd1 New Member

    Messages:
    26
    i use this amplifier paired with Vienna Acoustics bookshelfs.
    My amplifier is 100% original with original capacitors and transistors. i did only repair of the output relays, i did this then realized that sometimes one of the channels plays 30% lower than another one. I do recommend you this repair as well, as sound quality may change dramatically.

    in terms of performance my DC offset is within limits (as per manual shall be 0V), bias adjustment is 27mV.
    the only concern is high temperature of the transistors - may go up to 50C

    i like the sound quality except one thing - i have filling that my basses are to low and inarticulate but still i fully satisfied.

    i'm from Russia
     
  9. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    Ow i see.......
    Thats good to hear....bass is low but very tight . Its not boomy or flabby.
    What is ur comment on its imaging . And soundstage. Is it very good or soso
     
  10. Shavalievdd1

    Shavalievdd1 New Member

    Messages:
    26
    my room is small but i can feel clear picture and fully satisfied in terms of imaging.

    soon i will move to bigger house so hopefully will discover more

    also i do recommend you to try this amplifier in "power amplifier" mode. so you will eliminate problems with pre-amplifier board
     
  11. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    Ok. I wanted to know the speakers they drive well. If any recommendations are there . I have a klipsch 280F with my friend where the amp is right now . As for me i made audax speakers . Components n drivers Made in germany and france .
     

     

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  12. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    This 907 here runs ice cool. I now believe that it must be biasing at a lower value and needs to be corrected.
    I'd also want the face plate and volume pots switches to be cleaned up as they are also scratchy.... And disturbing the balance between speakers.
    Hope its not a big deal.
     
  13. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    I just re read this thread. U mentioned that your amp is a bit low in bass and is inarticulate .
    I just checked out my bang okufsen okufsen with much sweeter bass and superb detail too. However sansui was superior in grip,detail and clarity... The only thing lacking was some low end bass was missing and the articulation was not as good as id like .....and i believe my bias is set at a low value of around 18...
     
  14. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    And the amp runs at around 30degrees warm
     
  15. quadklipsh

    quadklipsh Super Member

    Messages:
    1,222
    Location:
    Lahore, Pakistan
    How to get the amp to play in the power amp mode .plz reply
     
  16. Shavalievdd1

    Shavalievdd1 New Member

    Messages:
    26
    connect your source or pre-amp to terminals with label "NORMAL" and select "NORMAL" mode, this will run your signal straight thru the power amp board
    upload_2018-5-15_9-49-0.png

    upload_2018-5-15_9-50-8.png
     

     

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