TV Volume Control

Discussion in 'General Electronics Chat' started by seecumulus, Aug 15, 2011.

  1. seecumulus

    Thread Starter Member

    Jul 13, 2011
    31
    1
    Hello -

    Model year 2003 - 32 TV.
    The TV's volume is increased or decreased by two front panel momentary pushbuttons - one volume + , one volume -

    My question is : Where do these momentary switches go in the Audio Amp Section ?
    How do the momentary switches increase and decrease volume and how do they simulate a Potentiometer ?
    :)

    Thanks !
     
  2. seecumulus

    Thread Starter Member

    Jul 13, 2011
    31
    1
    Without a schematic.
    My early investigation un-covers that this TV manufacturer of March 2003 must be using a Digital Volume Control IC based on a Up/Dn Counter.
    Now to find out what they actually used ?
    Similar chips : MAX5160 / MAX4252 or MAX5456 or similar ?
    Or possibly they used discrete digital logic for the Up/Down Counter feeding the Audio Circuit Amp.
     
  3. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    There are two ways:
    - Built into the audio amplifier IC is a volume control which adjusts the gain of an amplifier internally. The control is digital possibly using a DAC to control a VGA (variable gain amplifier) or tapping off resistors in an internal divider.
    - Or, more commonly, the digital signal processor (the main IC on the TV's main board) controls the volume by multiplying the output codes which go to the amplifier and headphones. This is more popular because tone and bass controls can be added as well as "virtual surround" (IMHO, it is a gimmick.)
     
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  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    If you posted a model one could try to find a schematic.
     
  5. seecumulus

    Thread Starter Member

    Jul 13, 2011
    31
    1
    Make and Model and Year
    Toshiba model 32A43 , March 2003
     
  6. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    The chassis is N3ES. In the 36A43 which has the same chassis number, the 3 signals KEY_A, KEY_B, and KEY_IN coming from the push buttons go to a microcontroller TMP88CP38ANG.
     
  7. seecumulus

    Thread Starter Member

    Jul 13, 2011
    31
    1
    That's cool !
    Thank you very much !
     
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