1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Sansui 9090DB noisy/dirty sound before and after cleaning pots

Discussion in 'Exclusively Sansui' started by Juan9568, Nov 5, 2018.

  1. Juan9568

    Juan9568 Member

    Messages:
    69
    Location:
    Buenos Aires, Argentina
    Hi guys.
    I'm going over the restoration of my amp and I'm still having this same issue. It sounds like dirty when listening and it makes a huge noise when I move the volume control knob, I have to do it very slowly so I don't blow off the speakers, needles go crazy. This same thing happens when I press any of the buttons of the push switch circuit board...

    At first I thought that this was because of dirty pots but after a deep cleaning the same thing happens.
    I thought also that maybe I had an issue with the equalizer board but after rebuilding, recapping and cleaning pots the issue remains.

    Strange thing is that when I choose FM radio I don't get any strange noise or scratchy pots. It works great

    I still have to recap the dolby board and the push switch circuit board, could the problem be in this section?

    All the other boards have been recapped and pots cleaned.

    I'll upload a video with the issue.

    Thanks!
     

     

    Please register to disable this ad.

  2. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

    Messages:
    3,256
    Location:
    NC
    Sometimes you have to clean the pots and all switches more than once, especially the Dolby switch. My 8080DB had to be cleaned 4 times before things finally cleared up. Don't give up! :)
     
    danrclem likes this.
  3. Juan9568

    Juan9568 Member

    Messages:
    69
    Location:
    Buenos Aires, Argentina
    Yes but I don't get this issue when listening to FM radio...Maybe the dolby board or the push switch is not grounded to chasis??..

    I realized that the dolby board doesn't work, I don't get the test tone..
     
  4. Juan9568

    Juan9568 Member

    Messages:
    69
    Location:
    Buenos Aires, Argentina
    Here a video:

     
  5. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

    Messages:
    3,256
    Location:
    NC
    Try cleaning ALL the switches again, Dolby and Selector switch as well....pain in the you know what but it fixed my issues. Hope it does yours as well.
     
  6. Tom B

    Tom B AK Subscriber Subscriber

    Messages:
    1,470
    Location:
    Bay Ridge, Brooklyn New York
    Hopefully you are using something like "Faderlube" (F5, or F100) for the volume and balance controls. It is the best for them. If you are using just a cleaner, they may stay noisy. Also check for DC volts on the volume control with is a sign of a leaky cap, or bridged connection when soldering in new caps.
     

     

    Please register to disable this ad.

  7. Juan9568

    Juan9568 Member

    Messages:
    69
    Location:
    Buenos Aires, Argentina
    Haven't gone through the dolby board and the push switch yet...The rest of them are clean and recapped...

    It sounds to me that something in the dolby or push switch board is wrong + that I don't get the test tone, because when listening to FM works OK
     
  8. Trnsfmr_Jr

    Trnsfmr_Jr New Member

    Messages:
    13
    Location:
    Oregon
    You absolutely sure that FM doesn't scratch too? Doesn't make much sense because Phono inputs and FM all go into the dolby board on the same two wires on the bottom of the dolby board. Grey and Blue wire on the bottom of the dolby switch board. Besides the phono preamp those inputs see the same path the whole way through. When you recapped the tone board there were a couple black ground wires connected to a few caps on that board. Those all make it back on there? If not I'm thinking you still might need another clean, or you got a DC voltage on the pot as Tom B said.
     
  9. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

    Messages:
    3,063
    Location:
    Tulsa Ok (C-Ville)
    You might want to check the ribbon cables at the input jacks. They can cause problems. Make sure all the outer sleeves of the RCA inputs are grounded to chassis for one.
     
  10. Juan9568

    Juan9568 Member

    Messages:
    69
    Location:
    Buenos Aires, Argentina
    Absolutely, FM works fine without noise...

    Black wires back in place..

    [​IMG]

    How would I get DC voltage on the volume pot?? In that case I should have that scratch sound while listening to FM
     
  11. Juan9568

    Juan9568 Member

    Messages:
    69
    Location:
    Buenos Aires, Argentina
    Maybe there's something there?

    Check out the back of the amp..is a mess

    [​IMG]

    [​IMG]

    What about that capacitor on the back of the chasis? Is that one normal? should I replace it?
     

     

    Please register to disable this ad.

  12. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

    Messages:
    3,063
    Location:
    Tulsa Ok (C-Ville)
    No. Leave that cap be.
     

Share This Page