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Sansui 2000X static hiss

Discussion in 'Exclusively Sansui' started by sansuilove, Dec 7, 2018 at 12:45 AM.

  1. sansuilove

    sansuilove Active Member

    Messages:
    261
    Hello.
    I’m enjoying this sweet receiver , but there’s a constant humm / hiss , doesn’t get affected by the volume.
    1. All notorious 2sc458 were replaced with ksc1845 .
    2. All caps been replaced (except the filter caps)
    3. Replaced R803/R823 with metal film resistors .

    Still, constant hiss.
    Any help would be great.
     

     

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  2. Gary Francks

    Gary Francks Active Member

    Messages:
    258
    Turn power off, remove pre-power jumpers and switch on again!
    If hiss and hum are still there, it's the power amp section, if not there then it's in the preamp!
     
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  3. sansuilove

    sansuilove Active Member

    Messages:
    261
    It has been done, and when jumpers are out it’s silent as dead.
    So It’s the power amp section .
    Can the supply board be the suspect?
     
  4. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Location:
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    I think you meant to say 'pre-amp section'. ;)
    Yes it can, but my money is on the pre-amp section in this case ;)
     
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  5. tom3

    tom3 Super Member

    Messages:
    1,950
    Location:
    So. Ohio
    Maybe some confusion here. Removing the power from the pre-amp section isolates all but the driver amps and outputs. Now there is no noise, so the noise is before that area. So is the noise in both channels? Noise in all input selections? Might be a power supply issue?
     
    sansuilove likes this.
  6. sansuilove

    sansuilove Active Member

    Messages:
    261
    I meant that the suspect is the power amp section because when jumpers are plugged , it has the noise.
    When they are out, no noise.
    I even used it as a preamp for another receiver I have (HK 330A) , and there wasn’t any noise.
     

     

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  7. sansuilove

    sansuilove Active Member

    Messages:
    261
    The noise in all inputs.
    Both channels equally.
     
  8. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Location:
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    In other words you are listening to the Power Amp ONLY.

    Gary Francks has it right in post #2

    The jumpers being removed are the pre-amp - power amp jumpers - are they not? in other words 'signal' jumpers (not the power to the pre-amp) - therefore the noise is coming from the pre-amp!

    Disconnect the pre-amp = NO noise - hence the power amp is quiet and an innocent party. :)

    OR am I misunderstanding the terminology you are using?
     
    Last edited: Dec 8, 2018 at 2:41 PM
  9. sansuilove

    sansuilove Active Member

    Messages:
    261
    Ok will rephrase
    I used the 2000x as a preamp with HK330A and it’s quiet.
    :)
     
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  10. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    48,601
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    It seems I am blind to mention of other manufacturers in the Exclusively Sansui forum. :D
     
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  11. sansuilove

    sansuilove Active Member

    Messages:
    261
    Went ahead and checked with my old scope
    This is the preamp with volume at max . Both channels clean signal (10khz)
     

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  12. sansuilove

    sansuilove Active Member

    Messages:
    261
    And this is the power amp board (c805/c815)
     

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