Sansui 881 hum - solved thanks to audiokarma!

Discussion in 'Exclusively Sansui' started by 1897, Nov 9, 2013.

  1. 1897

    1897 New Member

    Messages:
    6
    I purchased a very clean Sansui 881 (on ebay) that once connected had a moderate hum through the speakers when volume was at zero. It was slightly louder on the FM setting than the other input. It didn't increase when the volume was turned up so if you turned the music up loud enough you could not hear the hum. Still annoying though. After sorting through the many suggestions on audiokarma, I tried the a few of the simplest fixes first.

    1) Cleaned the connector on the driver board with deoxit
    http://www.audiokarma.org/forums/showthread.php?t=305438

    Still hummed.

    2) Replaced the ground braid between caps and pc board with heavy grounding braid (either stainless or tinned solder).
    http://www.audiokarma.org/forums/showthread.php?t=515756&page=2

    Hummed louder than before. But at least it seemed like a ground was a likely culprit.

    3) Replaced the braid with solder wick (not the prettiest solder job) to see if copper braid would work better.

    Still hummed but less, though similar to the original hum.

    4) I was ready to try replacing capacitors but luckily I kept reading the previous thread. dr*audio suggested tightening the screw on the pc board next to where the solder braid attaches (see photo). I tightened all the screws just for the heck of it. They all seemed fairly tight but I snugged them some more. Plugged it in and....

    No hum.

    Thanks Warren aka dr*audio
     

    Attached Files:

  2. peterfranks

    peterfranks Super Member

    Messages:
    2,927
    Thanks for posting - this is good additional information on this well documented issue with the Sansui xx1 family of receivers.
     
  3. Zekeman

    Zekeman AK Subscriber Subscriber

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    Chicago
    Hum is usually a ground loop. We used to deal with that problem years ago When I installed car stereos and car phones in the early '80's.

    Glad you found a solution.
     
  4. nosirrah

    nosirrah Moderator Moderator

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    Welcome to AK, we like happy endings....
     
  5. tyeeslayer

    tyeeslayer Super Member

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    Good to know, a 881 is the next thing to go on the bench for a hum issue.
    Thanks for the round up.
     
  6. markallen

    markallen Luddite Tendencies

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    1,124
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    I'll add my thanks as well. This just saved me a lot of time tracking down that darn hum!
     
  7. LexDM3

    LexDM3 AK Subscriber Subscriber

    Messages:
    1,970
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    Arlington, MA
    Same story here. I got an 881 fairly inexpensively because it hummed a lot. The dr*audio fix made the hum go away. The 881 is a really nice receiver.
     
  8. glenrob

    glenrob New Member

    Messages:
    25
    I did a google search of this issue as it's also happening with my Sansui 881. I did try tightening that ground screw on the power supply (as pictured by 1897), not doing the trick- maybe I have a different issue. I'll try to explain:
    I first began to notice that when I powered it on there would be a slight hum or buzz for a few seconds until a "click" noise and everything worked fine. The interval between power on and the "click" gradually got longer over the past few weeks. I'd say about 3-5 minutes. Tonight it began to simply buzz or hum continually without going back to normal. There is no input sound. I tried to tighten that screw. It didn't work. I turned the volume way up and can now hear more of a buzz in the left channel that does go up and down with the volume knob.

    Any guesses? Should I bring it to a repair place?
     
  9. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Yes, yours needs really repair.
     
  10. sregor

    sregor AK Subscriber Subscriber

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    Guesses - C11 (47uF 50V ) in protection circuit may be bad. Causes low supply voltage to relay. Buzz is probably relay trying to pull in. YMMV
     
    skippy124 likes this.
  11. EastPoint

    EastPoint AK Subscriber Subscriber

    Messages:
    4,433
    Location:
    Milwaukee, WI
    Hi, I took a look at this particular Sansui 881 tonight. I tightened the screws, reseated the card, etc. Nothing. Here's what's happening. When you turn it on, it turns on, but no sound. It then starts buzzing/humming right in the area of the relay. If you hit the relay with a screwdriver handle a couple times, it clicks and music plays. Otherwise it does not click. I can swap C11 tomorrow, but is it possible that the relay is bad as well? It's labeled Omron Type MY2. Should I replace it? If so, with what? There are a bunch of relays labeled "Omron MY2" on eBay and Amazon.
     
  12. EastPoint

    EastPoint AK Subscriber Subscriber

    Messages:
    4,433
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    I replaced Cap 11 with a new one and it now works perfectly and comes out of protection in 2-3 seconds. Thank you!
     
  13. sregor

    sregor AK Subscriber Subscriber

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  14. Fluff*Head

    Fluff*Head New Member

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    Another success story for me, too. Thanks!
     
  15. EastPoint

    EastPoint AK Subscriber Subscriber

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    4,433
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    Milwaukee, WI
    The damn thing has a weak channel now apparently. I'll take a look Saturday and report back.
     
  16. endo

    endo New Member

    Messages:
    14
    Location:
    Australia, Central Coast
    Hi, Just wanted to say a thanks to @1987 and @dr*audio for providing this fix. I have a Sansui 881 Stereo Receiver which sounds fabulous, it was suffering from the hum issue. I followed the steps and removed screws, washers and coated them with a deoxit combination and removed old solder from grounding holes in the 2 main bottom access PCB's and applied new solder and the hum has gone! I was about to purchase new filter capacitors too, this receiver still deserves a recapping anyway.
     
  17. Rebelkid12

    Rebelkid12 New Member

    Messages:
    10
    Location:
    Montreal Quebec
     
  18. Rebelkid12

    Rebelkid12 New Member

    Messages:
    10
    Location:
    Montreal Quebec
    Thank you! I hab a hum for ages and after reading your post i went straight to that darn screw! Problem solved!
     
  19. MagicMan

    MagicMan New Member

    Messages:
    12
    After reading this article about the cronic hum involved with so many sansui 881 receivers circa (1970-1974) I decided to take the advice about taking the bottom plate of the unit and tighten the Phillips screws holding the main board. Instead I tightened all boards just in case. I must say I had a hard time believing that this stated manoeuvre would even work at all but after reading other stories with other techs talking about soldering new wires and things to try and reground the board I thought I would at least try. All screws seamed pretty tight already but managed to at least barely barely tighten a couple anyway completely not believing this would do anything at all. Well after putting the bottom plate back on and firing the 881 back up much to my surprise the humming noise completely disappeared. One more thing I will say is that before when it dud hum it didn' get louder when turning up the music louder so I thought it did still sound very nice and I have also read other peopl saying don' worry about that humming noise and just use it since you can' hear it when you have the music up. Well let me be the first to tell everyone that ever tries this trick with success that I have also noticed a big improvement in the sound of this unit. I want to thank all those who share these types of trial and errors because I have a much better Sansui 881 receiver now. So with that said now I have to find someone to help me figure out why the tuner isn' working. Lol! I did discover one meter light burnt out which I pulled out before I put the cover back on which I will order. Also removing the cabinet off the unit was a beautiful thing because of all the dust over 44 years since new that built up. My air compressor gun did a fantastic job blowing it all out and pretty much looks new again. Thanks guys
     
    smurfer77 likes this.
  20. LBPete

    LBPete Rolling Along Subscriber

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    That's why it's called AudioKarma. Welcome. Please post the serial number for the database. Click on the link in my signature block.

    - Pete
     

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