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Speaker Noise Problem

Discussion in 'Troubleshooting and Repair' started by drjackool, Mar 25, 2015.

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  1. drjackool

    drjackool

    7
    0
    Apr 15, 2014
    Hello

    I have a microlab PROBIT M-2000 5.1 sound system (for PC). Now after about 13 years when I turn speakers ON a noise dropped on sound (like when applaying a sound effect by software) and I must turn the speaker OFF and then turn ON again for some times to clear the noise also when I touch the speaker or remove satellite speakers around the amplifier the noise comes back again.

    Please help
    Thanks
     
    Last edited by a moderator: Mar 25, 2015
  2. Tha fios agaibh

    Tha fios agaibh

    2,107
    708
    Aug 11, 2014
    Can you describe the sound better?
    Is it like a hum or a squealing sound?
    If the latter, it might be a cracked board or bad solder joint causing feedback oscillations. If you checked that already, it is probably a component failing. They can sometimes be detected by applying heat or cooling them down with compressed air.
     
  3. drjackool

    drjackool

    7
    0
    Apr 15, 2014
    Hi
    The sound is like a hum or like a far sound or bus loss, I open the PCB and resoldring all elements but not affected. and all capacitors have normal appearance.

    Please guid me
     
  4. drjackool

    drjackool

    7
    0
    Apr 15, 2014
    UP UP UP
     
  5. Tha fios agaibh

    Tha fios agaibh

    2,107
    708
    Aug 11, 2014
    I have no idea what that means. Nor what a far sound/bus loss is.
    Do you gave a schematic you can post?
    Is it a 60cycle hum, or more like white noise sound?
    How loud is this noise? What's your experience level?
    You need to offer as many pieces to the puzzle as you can for one of us to help.
     
    Arouse1973 and davenn like this.
  6. davenn

    davenn Moderator

    13,654
    1,888
    Sep 5, 2009
    totally agree with this
    we need lots more info for us to help you .... answer all those questions :)
    it wouldn't hurt for us to see a couple of sharp and well lit pics of the circuit board in the power supply area
     
  7. drjackool

    drjackool

    7
    0
    Apr 15, 2014
    Hi
    I provide some pictures from PCB
    WP_20150326_11_35_33_Pro.jpg WP_20150326_11_36_59_Pro.jpg WP_20150326_11_40_56_Pro.jpg WP_20150326_11_42_09_Pro.jpg WP_20150326_11_42_29_Pro.jpg WP_20150326_11_43_28_Pro.jpg WP_20150326_11_43_48_Pro.jpg WP_20150326_11_45_51_Pro.jpg

    BUS loss: Like when closing the bus volume.
    Far sound: Like sound are playing in bathroom.
     
    Last edited: Mar 26, 2015
  8. davenn

    davenn Moderator

    13,654
    1,888
    Sep 5, 2009
    that's shockingly bad cabling

    first thing to do is cut that cable tie and separate ALL mains voltage cable away from the signal cables

    so re-ziptie the thick red and blue mains cables together and move them away from ( as far as possible ) from the red and black cables etc that go to the speaker and input connectors

    Dave
     
    drjackool likes this.
  9. drjackool

    drjackool

    7
    0
    Apr 15, 2014
    I tried it, but not work.

    Also when I turning OFF for a semi-second (while i pressing power button) the sound be correct for a moment.
     
    Last edited: Mar 26, 2015
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