Scratching noise out of my speakers

Discussion in 'AV Receivers' started by Shawn Caw, Feb 2, 2006.

  1. Shawn Caw

    Shawn Caw Auditioning

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    I have just received an older sansui audio system, which I have read is really good. I have just hooked it up and when I turned it on there was a problem. There is a loud scratching/static noise coming out of both of the speakers. I have had this problem with other stereos but with them is was mostly when I change the volume level, but this one is different, it is all the time, and worse when I change the volume. Also at certain volume levels it only plays from the left or the right channel but not both of them, and the other problem is the balance control does not make anything different, until it is all the way to one side, there is no slight variations. If anyone knows what this problem would be please let me know, if you need more info I can also tell you that too. Thanks for the help
     
  2. Jay H

    Jay H Producer

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    Have you tried hooking the speakers up to a different receiver or would you be able to bypass the tone controls? Scratching static from changing volumes or changing the tone (bass/treble) is a common sign of a bad or dusty/dirty potentiometer which is what the basic analog volume/bass/treble switch is. If you can try a different source with the same speaker, you can isolate it to either being a defective/dirty receiver or a bad speaker (or both).

    Since you mentioned the tonal controls don't work, that could be another sign that those pots. are bad.

    Jay
     
  3. Ralphie_B

    Ralphie_B Stunt Coordinator

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    Do you have anything that is not a phonograph hooked up to the phono input? The reason I ask is that I recently moved some equipment to the basement and hooked it up to an older Pioneer receiver I have down there. I got a little careless and hooked my TV audio out RCAs into the receiver's phono in RCAs. The sound was VERY faint (not loud like you describe), however it was very scratchy and indistinct. I later learned that a phono input expects a different level of signal than a TV/VCR/DVD/CD input. Just something to check.
     
  4. Shawn Caw

    Shawn Caw Auditioning

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    hey jay,

    I have the speakers hooked up to an old pioneer reciver and they work awsome, so the problem is the sansui amp. I did try pulling it apart to check the controls, but everything looks clean, and I can't feel any dirt or dust on the contacts. is there a good way to clean the potentiometer, or does it have to be replaced?
     
  5. Jay H

    Jay H Producer

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    You could try to buy some contact cleaner from say Radio Shack, it should be an aerosol can with a small straw on it (much like the kinds you'd find on WD-40). However, by the sounds of your description, the receiver sounds worse than dirty and a little contact cleaner might not help, but you can always try...

    Replacing a pot might not be difficult, if that is the problem, heck, if you're somewhat handy and know how to solder, it might be doable yourself. It isn't a $4000 Krell, so hey, what the hey. However, you would first have to figure out where to get parts and what part to get, the values of the pot itself, etc. etc.

    Jay
     
  6. Nhoj

    Nhoj Auditioning

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    How old is this sansui?
    It needs professional help, unless you're up to doing the following...
    Spray WD into every knob, switch, rotary wafer you can get at. Mutate the straw as needed. Just a spritz, then twist the knob or rattle the switch a whole lot. Look for any switches in the back.
    Look for a circuit board with medium sized transistors fastened to tall heat sinks. They are called regulators. Resolder their leads, leave them shiny.
    Look for the speaker relay (or turn it on and listen for which one it is), unsolder it, pry off its lid and use a thin file to scrape the contact points. (all while unplugged, of course)
    If there are any incadecent bulbs in sockets in the front panel, excavate them and scrape their bottoms and the bottom of the socket.
    That should nail the scratchy sound, probably.
    Of course, it could be the dif amps at the front end of the power amp...
    Those big old tubs had beefy supplies and lovely sounding tuners.

    Cheers
    Nhoj

    PS- These tips do not apply to a/v receivers made after the late 80's
     

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