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Vizio VW26L has picture but no sound

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    Vizio VW26L has picture but no sound

    I picked up this defective Vizio tv model VW26LHDTV20F at a garage sale with no picture or sound. After replacing 11 caps on the power supply bd I now have a great picture but no sound thru the speakers. I do have sound via the earphone jack. Menu settings for audio are enabled and the volume sound bar indicator moves via the remote controller. 5V, 15V, 12V and 24V outputs are correct.
    I have 15V to the VDDs of theTFA9810 audio amp chip. Pin 7 ENABLE never goes high but is not shorted to ground. I do not have a schematic so not sure what should drive pin 7 high.
    The two speakers test good also. Same result with HDMI or cable input.
    I appreciate all the help I can get.
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    #2
    Re: Vizio VW26L has picture but no sound

    See if there is a speaker on/off setting in the menu. check the earphone jack switch to make sure it is switching the speakers back on. when earphones are pluged in they usually mute the speakers. The pdf for this chip says that pin should be +3 volts to operate, trace that pin back to see what controls it.
    Last edited by R_J; 12-02-2015, 04:14 PM.

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      #3
      Re: Vizio VW26L has picture but no sound

      Thanks for your reply.
      There is no speaker on/off option. It doesn't look like the earphone mute goes to the ENABLE pin. Couldn't trace the pin back to its source as it runs under the chip.
      I'm wondering if this tv needs a eeprom reset.
      Another thing is that I'm running this via my ISP's (Brighthouse) remote as I didn't get the Vizio remote with the TV. Don't know if the original remote would help the initialization.
      Does anyone have the schematic for a Vizio VW26L?

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        #4
        Re: Vizio VW26L has picture but no sound

        I dought you will find a schematic, I have found a few vizio service manuals and you might get a block diagram if you are lucky. It could be a fault with the eeprom, I have seen it before where a tv had no sound and the fault was corrupt eeprom data.

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          #5
          Re: Vizio VW26L has picture but no sound

          The pin 7 ENABLE seems to be coming from another chip rather than directly from the earphone mute. I'm thinking that that chip mutes sound when there is no broadcast in addition to earphones plugged in. Strange that pin 7 is always measuring 0.7mv. I thought it would be one junction drop of about .7V.
          As I stated before it does not measure a short to ground.
          I tried doing the reset function from the main menu but that did not help.
          I'm still looking for the service manual for this Vizio VW26L.
          An alternative may be for me to free up pin 7 and tie it to +12V thru an RC network so that it goes high after a power up delay.
          Any other thoughts?

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            #6
            Re: Vizio VW26L has picture but no sound

            An RC network to +5V may be better than to +12V.

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