Sansui AU-9500 filter caps and rectifers

Discussion in 'Exclusively Sansui' started by Mico, Feb 28, 2018.

  1. Mico

    Mico Active Member

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    I am completing parts order for AU-9500 restoration, one last thing I am not sure about are filter caps and rectifiers. Original caps are puny 4700mF and should be brought up to at least 6800mF but what worries me are the rectifiers. They are already well known to be unreliable and upping the capacitance would put even more stress on them. Which rectifiers would be a good solution, either as plane replacement with original 4700mF values or even better for 6800mf - 10.000mF ? And what about the power switch, would stock one be O.K. in 9500 "turbo" version?
     
    Last edited: Mar 1, 2018
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  2. kevzep

    kevzep Its all about the Music Subscriber

    I put 10,000µF caps in my one on the standard rectifiers, as far as I know after selling it to a colleague, its still running.
    Although it wouldn't hurt to throw some up-rated rectifiers in there....just for preventative maintenance.
     
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  3. Mico

    Mico Active Member

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    Thanks Kevin, I will go for 10.000 than. Is there any chance you know what values are bias and DC offset adjusting trimmers?
    Can not figure that out from SM and old ones are so badly oxidized I would not dare to touch it, let alone adjust anything.
     
  4. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    upload_2018-3-1_18-59-36.png

    Is what I could find in the SM - but maybe you should measure yours with a multimeter just to be sure?
     
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  5. slimecity

    slimecity Super Member

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    The schematic may also describe the trimmer values in the circuit diagram - have a look at that too.
     
  6. Leestereo

    Leestereo Super Member

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    +1
    Installed 10,000µF/63V Nichicon KG capacitors >2 years ago and no issues to date.

    au9500 main caps.jpg
     

     

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  7. Leestereo

    Leestereo Super Member

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    Trimmer VR801 is 5kohm; VR803 is 200ohm.
     
  8. Mico

    Mico Active Member

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    Location:
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    Thanks Lee, I forgot to look at your excellent post regarding 9500 restoration. It was beautifully illustrated - but none of the images are available any more, did you think
    about uploading them directly on AK again? Hyperion`s image of SM with VR-802 marked as Bias trim pot is confusing, same as I see in my SM - and no VR-803 in the parts list? But in that same SM, VR-803 is noted in Bias adjusting procedure...obviously another Service Manual mistake.
     

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    Last edited: Mar 1, 2018
  9. Leestereo

    Leestereo Super Member

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    The thread images are still on Photobucket; they have changed its 3rd party hosting policy and this has affected most of my AK threads. The embedded Photobucket pictures can be viewed with a Chrome Extension (https://chrome.google.com/webstore/...nk-fix/kegnjbncdcliihbemealioapbifiaedg?hl=en) or a Firefox Add-on (https://addons.mozilla.org/en-US/firefox/addon/photobucket-embedded-fix/).

    I have noticed that at different times one or the other workaround will stop working; currently, at the time of writing, the Chrome workaround allow the pictures to be viewed within the thread.

    Regarding VR-803 is the notation for the bias adjustment trimmer in the schematic.
     
  10. kevzep

    kevzep Its all about the Music Subscriber

    Nice job getting the Gold Tunes in there....not always an easy fit..
     
  11. Mico

    Mico Active Member

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    Location:
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    Big 10.000mF KG caps are in but did not upgrade rectifiers yet....very awkward position of bridge rectifiers and limited space to deal with.
    So far so good , will try to ft in at least 10A bridges instead of originals.
     

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    Last edited: Apr 6, 2018
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  12. Mico

    Mico Active Member

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    Went to adjust Bias on Au-9500 and found this...someone at Sansui liked Russian roulette - distance was less than 1mm!
     

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  13. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    They are connected to the same spot, don't worry.
     
  14. Mico

    Mico Active Member

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    Got it, still flimsy craftsmanship.
     
  15. kevzep

    kevzep Its all about the Music Subscriber

    Yep same junction, no problem there at all, sometimes they use plastic sleeve over the legs sometimes not....
     
  16. Leestereo

    Leestereo Super Member

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    Here is a picture of a potentially more damaging situation (yellow arrows point to clipped off pieces from the output transistor leads):
    GFA-545a.jpg
     

     

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  17. Mico

    Mico Active Member

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    Yikes, are they hanging from the thermal compound? Which unit was that ?
     
  18. Leestereo

    Leestereo Super Member

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    Yes, just waiting to fall and cause a short...Adcom GFA-545.
     

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