Main Filter Caps Replacement for Sansui 9090DB??

Discussion in 'Exclusively Sansui' started by Juan9568, Jun 13, 2018.

  1. Juan9568

    Juan9568 Member

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  2. RR--

    RR-- Active Member

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    Hipocrates Anti-Muppet

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  4. Juan9568

    Juan9568 Member

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    Thanks! Yes they're a bit pricey. 15000uF wouldn't be too much for the power relay?

    What type of resistor is on the back? I mean ohms and wattage?
     
  5. Tom B

    Tom B AK Subscriber Subscriber

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    You can use the original 4.7K resistors on the new caps. Those resistors are basically to discharge the caps after power off. They arent components that get any undue stress. Just be careful on the height of the main filters, as you are limited in the 9090db because of their location.
     
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  6. tnsilver

    tnsilver AK Subscriber Subscriber

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    Absolutely correct. The 100mm length capacitors are not gonna fit. The stock "black negative" caps are 80mm and barely leave a gap to the tone control PCB's.
    15000uF are pretty common replacement but technically it's not the realy that's at stake, it's the rectifier bridge diodes at the inrush current stage, while those huge caps are charging on fire up.
     
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  7. Hipocrates

    Hipocrates Anti-Muppet

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    nah they will be ok.
    Those are bleeding resistors, 2W 4.7k, and yes 100mm is too tight... my bad
     
  8. Juan9568

    Juan9568 Member

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  10. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

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    Removed
     
    Last edited: Jun 13, 2018
  11. tnsilver

    tnsilver AK Subscriber Subscriber

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    I got 100mm KG Super Through's like these, back in 2012. I was under the impression they were discontinued already by then.
    It's easy to under-estimate just how huge these 100mm caps are. The super through's go in a 65mm clamp.
    Maybe the "Goldtune" KG variant is a little thinner but I am not sure they go up to 80V with 15000uF. Mine are like coke cans.

    The only way a 100mm tall cap is going in a 9090DB is over the equalizer board, using a specially crafted cross member section for support.

    That's my cross member section based on member @naderpe's design:

    [​IMG]

    [​IMG]

    There's no way 100mm tall filter caps will fit in the stock location. I had this aluminum cross member section made for me by a specialist:

    [​IMG]

    [​IMG]
     
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  12. ManyMoonsAudio

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    Good catch. I seen that 100mm was mentioned, so I assumed (not good) 100mm would go. Been awhile since I replaced filter caps in a 9090DB.
     
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  13. Juan9568

    Juan9568 Member

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    That's great! I'd love to do that mod on mine...maybe in the future...For now I need to go with some caps that fit like the originals
     
  14. Tom B

    Tom B AK Subscriber Subscriber

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    What are the originals reading?? Sometime they are fine, and well within tolerance. If I find them at 90% I usually leave them as lond as ESR is real low as well.
     
  15. Juan9568

    Juan9568 Member

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    I don't know but they are like 45 years old and as I will be doing a full recap it's be better that I replace them....
    I also noticed that all the lighting of the amp starts flickering from time to time and sometimes they don't even turn on.
     
  16. ManyMoonsAudio

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    Sansui used very damn good filter caps in these though, I will say. I have yet to see a set of them actually bad in the 9090DB.
     

     

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  17. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    No need for swearing :rflmao:
     
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  18. tnsilver

    tnsilver AK Subscriber Subscriber

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    Following your other threads, I do have a hunch your filter caps aren't 100% solid, but flickering lights is not a manifestation of it. There's a dedicated 6.1VAC line (brown leads) from the power transformer to take care of incandescent illumination and it's oblivious to the filter capacitors. It likely has to do with dirty/loose fuse holders on the PS board, bad contacts, and possible hairline rail cracks. Bad filter caps don't even manifest in a scratchy output, which is more likely a result of dirty tone controls/ rotary switches, and fuse holders again. Bad filter caps result in very poor power hungry lows and cause bass to sound unfulfilling. Since bad filter caps don't do so well on filtering, DC spikes can drive the protection circuit crazy and make it act up arbitrarily. I think you might be right, albeit flickering isn't a symptom in this case.
     
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  19. Tom B

    Tom B AK Subscriber Subscriber

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    This is why I usually don't replace them. I have only found one bad cap (It was only reading 8,500uf instead of 12,000uf) in the 15 or so Sansui 8080db,(8080db may use a 10,000uf) 9090, 890db, and 9090db I have worked on.
    But I can't say the same about the Sansui G8000/G9000. They use dual supplies with dual caps per supply for a total of 8 large filters. I had a G8000 or G9000 that I repaired that had very poor power out, and almost no bass at all. All of the caps were only reading 45% to 55% of their rated value. I replaced them all and bass and power was now back.
    tnsilver is right on about the lights. Those receivers use fuse lamps that run so hot that they create cold solder connections where the lamp holders connect to the illumination circuit board.
     
  20. Hipocrates

    Hipocrates Anti-Muppet

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    :rflmao::rflmao::rflmao:Ok, here we go again

    [​IMG]
     
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