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Thread: M2-ATX Interferences to LCD

  1. #1
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    M2-ATX Interferences to LCD

    Hi have D945GCLF2 motherboard w/ TV-out powered by M2-ATX connected in my car. The S-Video signal has some horizontal interference going up to down on my LCD screen. I got the same behavior when I powered the M2-ATX from CarcPC from an external 12VCC 5A charger with S-Video connected to my LCD TV. Thus, there is not something wrong in my car, because I got the same behavior in my home.
    I used quality SVHS cable, I connected the CarPC ground to car chassis mass.

    It's something wrong with M2-ATX or with TV-motherboard?

  2. #2
    Neither darque nor pervert DarquePervert's Avatar
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    Have you tried a different SVideo cable?
    Have you looked in the FAQ yet?
    How about the Wiki?



    Under normal circumstances, a signature would go here.

  3. #3
    Raw Wave
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    Mickz did some brilliant investigations and solved noise issues with the M4.
    Unfortunately it's a long thread, but see the pics on power supplies with minimal radio interferance? (page 16) and a the closer feed through capacitor pics on page 21.

  4. #4
    Variable Bitrate
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    Does it happen with other connections other than s-video?
    I had so many issues when trying to connect things with s-video i gave up, does the LCD have any other type of connection that your PC supports?

  5. #5
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    Yes, I used different SVHS cables with my TV LCD. The same issue is with VGA signal output as well. In car LCD I have SVHS only. Probably the power M2-ATX ground is not well connected to case chassis. Mickz suggested to use a 8G lead between earth of M2-ATX and metalic cover of SVHS socket from motherboard. My ccarPC case is VoomPC2.

    Could be something related to the M2_ATX filter capacitors. Should I change it?

  6. #6
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    I think I found the root cause of my problem. Opening the CarPC and looking to M2-ATX, guess what? All 6 electrolytic capacitors on output voltages were bloated. I'm looking to find something similar for 1500uF /10V and to replace them. Other issue that generates the interference was from chassis fan. Probably this is related to the capacitors. I powered the fan from other 12V power supply and the interference disappeared, but still I have small interferences. Next step is to replace the capacitors.

  7. #7
    Raw Wave
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    Well done - especially the fan re-sourcing! (I forgot - they can be noisy burgers.)

    With the caps, just ensure adequate voltage rating. I usually go the "next one up" - ie, 10V, 16V, 25V, 50 or 63V etc, eg for automotive 12V use (meaning up to 14.5, 15, 16V etc) I'd chose 25V rated caps rather than 16V.
    That means a larger physical size (fatter; a more insulation or bigger gap between the plates) which can be a problem, but then I might sacrifice the cap size (Farads) instead, or even use low-ESR electrolytics for filter capacitors.


    The higher the conversion frequency, the lesser the filtering required (for low-ripple dc output). I am often surprised just how much output capacitance is used in dc-dc converters.

  8. #8
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    Thanks. I replaced the capacitors but no significant improvement. Probably the capacitors were not damaged. In addition to changing the power supply for chassis fan, I connected the LCD chassis to the car chassis mass using a short 8G wire. My LCD is OEM display (Opel CID) with video interface. Now everyting is OK.
    Thank you all of you for helping me.

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