Problem with tv decoder - Greed Led is blanking and there is no change after pushing Power

Discussion in 'Technical Repair' started by UnnamedUser159, Sep 17, 2016.

  1. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    Hi there.
    I have in my hands one tv decoder.
    The man said that the LCD display is not working and that the diod wont goes differrent color > the decoder isn`t working /only the green LED is blinking/

    Tell me for example what can i check to find something failed which can help fixing device. I dont have oscilloscope. I have ESR meter, capacitance meter and digital multimeter

    https://drive.google.com/file/d/0Bxome1ZSCRIaSFlWYVNRRU9UNTc2cnVkYm9za3M2elVPTVlJ/view?usp=sharing
    https://drive.google.com/file/d/0Bxome1ZSCRIaZGlPNWxoc2tiSkFwa3p0WEFvYU9QMGR5elZz/view?usp=sharing
    https://drive.google.com/file/d/0Bxome1ZSCRIaZ0hNTzNWWURuY3l2Z1R2SUhMVGZaaTdXQ0ZF/view?usp=sharing
    https://drive.google.com/file/d/0Bxome1ZSCRIaZHRMYlNMTkNiUndZZkpRN2JDSFFJNVdvQmI4/view?usp=sharing

    IMG_20160917_135834.jpg
    IMG_20160917_135815.jpg
    IMG_20160917_135800.jpg
    IMG_20160917_135855.jpg

    I have degree in electronics but even after some practise i am defenetely not Repair Master :)

    If there is a article which can be usefull to me please link to it.

    Thanks



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    Last edited: Sep 19, 2016
  2. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,150
    205
    Before you do anything at all. ZU4 looks like a diode bridge. Hopefully it has markings. Identify the power rail(s) on any IC or try ZU4. Anyway try to identify any IC and it's power rail. he numbers on the chips may be readable or the SMD marking codes can be looked up.

    What I want you to do, is with it unplugged as you have it, short that power rail for at least 24 hours.

    Remove the short and try to power up. it's not voodoo. It may work.

    If you can't really locate the power rail, lay the pcb on a piece of alluminum foil with a bit of pressure. You may do both for at least 24 hours. Remove the PCB and the short, assemble and try to power up.

    Be warned that that swtchmode power supply may have 400 V or so across the main cap when plugged in.

    One of the first things is to check power supply voltages. there may be 12, +5 and 3.3. and/or some voltages always present. Since nothing is smoked, do the short thing.
     
  3. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
  4. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
  5. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,150
    205
    Don;t worry about that yet. Just sit the solder side of the PCB on a piece of aluminum foil tightly on a piece of aluminum foil at least overnight, but DO REMEMBER to remove the aluminum foil before powering it up.

    I know it sounds sill, but it MAY work. It has reasons to work.

    I'll look at the datasheet later. Hopefully Google Translate will work.
     
  6. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    i put the board on cooking folio for one day and there was no effect.
    The LED blinks in green and there is no change after short push and long push(power button)
     
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