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Thread: would a VGA "amplifier" solve LCD hum??

  1. #1
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    would a VGA "amplifier" solve LCD hum??

    hey guys. i'm tired of not being able to solve the noise problem in my car, so i decided to just hide it. so i was wandering. has anyone tried using an active vga splitter or amplifier, to "Clean" the signal? do you think this will work??
    also, if my vga-card had an HDMI (it does not), would , hooking a hdmi to vga converter solve it??

  2. #2
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    You need to describe the noise.

  3. #3
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    the classic hum. its preiodic, with some spikes now an then, but, it gets stronger with longer vga cable. 1.8 meters, and i have no noise. add enother 1.8 , and i got enough noise. 5 meters are noisy as ****.
    although i dont know if it is the same noise, but in the speakers, you can hear noise that has its peak at 1khz , and goes up with my RPM (2000rpm = 2khz and so on... )

  4. #4
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    Sounds like alternator noise to me.

  5. #5
    Raw Wave
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    Certainly signal degradation - ie, decreasing S/N ratio. But whether it's loss of signal thru the cable or induced noise....

    A better cable may solve it, or maybe suppression caps or toroids, or even breaking of the shielding at the LCD end.
    Otherwise an amplifier may be required, but more info or investigation is required.


    CORRECTION... - corrected "...breaking of the signal GND (maybe shielding) at the LCD end." to "...breaking of the shielding at the LCD end."
    Last edited by OldSpark; 08-18-2013 at 09:16 AM. Reason: CORRECTION...

  6. #6
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    well. i opened both cables i've been using . 5m (LOTS of noise) and the 1.8( clasic blue vga cable wich comes with new LCD. NO NOISE at all, (if it is alone) ) .

    both seemed to be exactly the same from the inside. what troubles me, is that you cant really "Cut the shielding of the isolation"... the rgnd,bgnd,ggnd, are all striped inside smaller insulations, that in turn, touch the cable insulation. so in a way, it is just ALL the grounds are connected together, with the shielding... any idea if it has anything to do with the noise??

  7. #7
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    so i was thinkink. what if i cut ALL the grounds from the vga cable?? will this be bad?? also, if i cut them. do i ground them somewhere else on the chasis, or do not cut them at all?

  8. #8
    Raw Wave
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    Sorry, I meant the shielding - not the signal grounds (they are required).

  9. #9
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    well, shileding is sorted with the signal grounds, in all the cables i have seen so far so... :/ . tommorow i will try to make a cable with CAT5 cable. see how this goes otherwise i will buy an amp!

  10. #10
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    What do you mean by "shileding is sorted with the signal grounds"?
    Either the cable has a shielding sleeve or sleeves, or it doesn't.

    "Analog" cables usually have shields whereas "digital" cables like Cats 5 & 6 may or may not have shielding. (Yes, I know there is no such thing as digital transmission and that analog & digital maybe somewhat arbitrary as asigned to cables.)

    Do you mean that cables with twisted pairs tend to "cancel" noise? If so, I understand what you mean, but that is not "shielding".
    Apparently most Cat 3 to 5 or 6 cables are unshielded though I almost exclusively used shielded Cat 5 & 5e etc - not that I/we terminated the shield(s).
    And I know that for digital comms, if the (Cat 5 etc) shield is used, then it "must" be continuous and that that may contradict noise elimination methods in analog systems (ie - discontinuous shields).


    Not that I want to get into the subject of shielding etc, but just in case you confuse (multiple) ground wires with shielding and might therefore overlook a good solution.

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