Page 4 of 5 FirstFirst 12345 LastLast
Results 31 to 40 of 49

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

  1. #31
    Variable Bitrate
    Join Date
    May 2010
    Location
    Herákleion, Iraklion, Greece, Greece
    Posts
    329
    yea, but my point was, if i could make a filter either or the power lines (low or high pass), either on the M4 rails. maybe the signal distortion comes from there?

    here, in M4's difence, i have to add, that with a diferent setup (ac inverter, and 220v PSU), i had the same problems. only diference when i cuted the "Ground" wire from the AC line of the inverter, the noise had went away...

  2. #32
    FLAC SNOtwistR's Avatar
    Join Date
    Nov 2009
    Location
    Keswick,On Canada
    Posts
    1,619
    settra I would search the forums for post by Mickz and the M4. He has done very extensive diagnosing to the noise related to the M4. I think you will find all your answers in his posts. here is a small clip from one of his posts.

    Hi JJ, I posted this on the other thread but thought I would post here as well for anyone searching for M4 interference. The M4 is the main culprit, PC can be generate some but to a lesser degree and finally any device with an SMPS, such as a (some) cameras. It's a pain to have to go the expense and hassle of fitting the PSU into a correctly RF screened case, and even then placement and lead dressing around the PC are still important.
    It's not going to be easy to find a PSU that is (truly) free from radiated interference. You really need to find four or more people with PSU brand X that are running DAB-FM and GPS and have tested reception using a laptop (PSU on and off) out of the metropolitan area where reception is not saturated with DAB-FM signal levels. I have seen people fluke an installation with an M4 and have no reception issues in their location. I have technically proved beyond any doubt that the M4 is a noise generator, but so too are most SMP supplies, it just comes down to how much they produce.
    You seem to be going around in circles trying to find your problem and you may never get it right. He has some good tips to at least try and get it to a liveable level. SNO

  3. #33
    Raw Wave
    Join Date
    Nov 2009
    Posts
    2,118
    Well if you want to solve the M4 issues, have a look at power supplies with minimal radio interferance? page 21. That is probably the extraordinary Sir Mickz's Esq's M4 reference that the talented Mr SNOtwistR (Esq.) is referring to.

    The inverter - AC PSU solution you speak of is a classic ground loop solution.

    But ATX dc-dc converters is the way to go, however maybe not using Mx's based on their known noise issues.


    Hopefully this is the last you'll see of me in this circle. (At least I am hoping so!)

  4. #34
    Constant Bitrate
    Join Date
    Nov 2012
    Posts
    140
    Quote Originally Posted by settra View Post
    so... some extra info, today i was using a speaker , as an osciloscope ( i know, i am poor:P ) just to see if there are AC currents. the results where those:

    There is an AC directly on the Alternator's output.
    there is AC where the power is pluged at th M4-atx.
    when i power the M4, the ac at its input, grows stronger,
    when i power the M4 there is (ofc) loads of AC, in its 12,5,3v rails....

    those AC, do not neccecery have to do with ground loops, do they?
    I said that in post #4.

    You need to determine if your power source is the cause or not.

    This thread is almost entertaining.

  5. #35
    Raw Wave
    Join Date
    Nov 2009
    Posts
    2,118
    Yeah - these threads tend to be entertaining.
    At least for readers.

    Of course there is AC present (d'oh!).
    Has anyone said it's (probably) the M4??

  6. #36
    Variable Bitrate
    Join Date
    May 2010
    Location
    Herákleion, Iraklion, Greece, Greece
    Posts
    329
    So my question is this. since the noise stays exactly the same , even when i power the LCD completly from a diferent power source (home outlet via ac to dc). does this kill the change of the noise being a ground loop? (or it could still be a ground loop between the signals and the power of the VGA card??)

    i am asking because redheadedrod gave me an idea with the USB vga. IF the problem stays even with the USB card, then i could completely cut the power of the usb wire, and give power to the vga card via a diferent PSU , which can have allot of filtering so it filters out any noise from the pc and alternator (That way i wont have to filter the whole PSU). (that ofc wont solve the change, the noise going to the USB via the D+ , - )

    any ideaS???

  7. #37
    Raw Wave
    Join Date
    Nov 2009
    Posts
    2,118
    When you say "home outlet via ac to dc", is that still powering/using the M4?

  8. #38
    Variable Bitrate
    Join Date
    May 2010
    Location
    Herákleion, Iraklion, Greece, Greece
    Posts
    329
    nope. no conection to m4-whatsoever. the LCD takes dc. so i just used a diferent AC-DC 12converter

  9. #39
    Raw Wave
    Join Date
    Nov 2009
    Posts
    2,118
    So M4 not even powered...

    So back again...
    Different power paths... ?

  10. #40
    Variable Bitrate
    Join Date
    May 2010
    Location
    Herákleion, Iraklion, Greece, Greece
    Posts
    329
    no, the m4 WAS powered. it powered the PC. it just not powered the LCD. i'm asking JUST for the ground loop. (ofc the noise comes from the M4. but if its not a ground loop as well, i could filter it from the USB line)

Page 4 of 5 FirstFirst 12345 LastLast

Similar Threads

  1. Replies: 0
    Last Post: 09-13-2007, 01:28 PM
  2. Replies: 2
    Last Post: 08-09-2004, 02:49 PM
  3. Replies: 0
    Last Post: 06-14-2004, 11:01 PM
  4. Amplifier Control - Avoiding "Thump"
    By marklamond in forum General Hardware Discussion
    Replies: 14
    Last Post: 11-20-2001, 03:23 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •