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    LCD displays flickering using VGA but HDMI not flickering

    Hello again...we have about +1000 of lcd displays in the fab, around 40% of it are flickering (but text still readable). Our facility staffs check all groundings from those flickering but all were fine. During investigation, the flickering goes out when using HDMI instead of VGA. But it is not cost effective to replace all with HDMI...Thus, we need some inputs from you experts on how this flickering happens when using VGA but other display ok with VGA. Need suggestion on how to resolve it in minimal cost. Thanks in advance.

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    Re: LCD displays flickering using VGA but HDMI not flickering

    Hi,

    What technical informations did you give that we can use to find a solution?

    When a monitor flickers, then usually it's because
    * monitor type: input signal range
    * graphics card output signal: resolution, frame rate,
    (Maybe even a mature "interlaced" signal is output by the graphics card)
    * noise introduced into the monitor cable (signals): cable type, shielding type, cable length

    Klaus
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    Re: LCD displays flickering using VGA but HDMI not flickering

    is the 'flickering' exist on the monitors from the beginning(when monitor is new ) or is it a new problem surfaced slowly with time?



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    Re: LCD displays flickering using VGA but HDMI not flickering

    Quote Originally Posted by srizbf View Post
    is the 'flickering' exist on the monitors from the beginning(when monitor is new ) or is it a new problem surfaced slowly with time?
    Yes..since the start about 10yrs ago...only this moment people decide to take action "(.



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    Re: LCD displays flickering using VGA but HDMI not flickering

    OK today we found something new today....when we dont connect the ground to the cpu and monitor supply the flicker goes out. I mean from the ac power plug going to the pc/monitor only live and neutral connected (no earth ground), it works...So weird and not safe...any idea guys? Is there something need to do to the video card groundings or monitor groundings?

    I found this from google --> https://mrgnome.wordpress.com/2009/0...roblem-solved/
    It should be safe, but really appreciate if someone can help me understand this...thanks
    Last edited by i200yrs; 28th November 2019 at 15:28.



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    Re: LCD displays flickering using VGA but HDMI not flickering

    what is the voltage between ground and neutral?


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    Re: LCD displays flickering using VGA but HDMI not flickering

    Hi,

    What do you expexct?
    We don't know about the cable, the wiring....you just give vague and incomplete informations.
    And it seems you don't read our posts....

    Klaus
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    Re: LCD displays flickering using VGA but HDMI not flickering

    Quote Originally Posted by KlausST View Post
    Hi,

    What do you expexct?
    We don't know about the cable, the wiring....you just give vague and incomplete informations.
    And it seems you don't read our posts....

    Klaus
    My apology mr Klaus...i read your posts am done checking your advice in post#2....but all ok when we compared with non-flicking units.

    - - - Updated - - -

    Quote Originally Posted by srizbf View Post
    what is the voltage between ground and neutral?
    OK let me check this out...we missed to measure this, good tips....thanks



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    Re: LCD displays flickering using VGA but HDMI not flickering

    From one of the flickering unit ground & neutral is 1.36Vac....but from good unit is 0.7Vac....is it safe to add jumper to short ground and neutral from flickering unit? thanks



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    Re: LCD displays flickering using VGA but HDMI not flickering

    NEVER short Ground and Neutral.
    Make no mistake between my personality and my attitude.
    My personality is who I am.
    My attitude depends on who you are.



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    Re: LCD displays flickering using VGA but HDMI not flickering

    the flickering unit ground wiring has problem . Trace the ground wire and follow it to the point where it is actually grounded. There may be corrosion or even loose connections in the path.

    shorting is not advised.



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    Re: LCD displays flickering using VGA but HDMI not flickering

    Quote Originally Posted by srizbf View Post
    the flickering unit ground wiring has problem . Trace the ground wire and follow it to the point where it is actually grounded. There may be corrosion or even loose connections in the path.

    shorting is not advised.
    We have tried to connect the flickering unit ground and non-flickering unit ground using jumper wire but not helping....if the ground have problem, why using hdmi doesn't flicker...It flickers only when using vga...any idea guys? thanks



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    Re: LCD displays flickering using VGA but HDMI not flickering

    Hi,

    any idea guys?
    VGA = analog. Any influence in analog signals will be shown on the screen
    HDMI = digital. More tolerant against noise, until the noise is big enough to make HIGH --> LOW ore vice versa.

    Klaus
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