Input and output for power adapters.

Discussion in 'The Projects Forum' started by connmannic, Nov 23, 2008.

  1. connmannic

    Thread Starter Member

    Nov 23, 2008
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    I have problem that seems simple enough, but is completely stumping me.
    I recently bought a touch screen lcd monitor off ebay.
    The brand name is NIS, which, from what I have gathered, is part of ELO displays. The monitor was not new, its probably around 6 years old.
    It is a 14 inch display.

    Here is the issue. It does not have a power adapter. The plug for the power is some old cpc plug, this was probably in some hospital set up where many monitors were powered with one power supply. The power rating for the display says it is a 12V/3.5A Max.
    I talked to someone who bought the same monitor on ebay, and they said they used the 12v 3a adapter for their external hard drive and it worked. They have yet to respond to my email asking them if the adapter is ac or dc.

    I am lost, I can not determine the current type for the monitor. How can I figure out what type of adapter I need?
    Does a DC adapter have the same output as an AC adapter?
    Would something like this work?
    http://cgi.ebay.com/NEW-LCD-Monitor...14&_trkparms=72:1205|66:2|65:12|39:1|240:1318

    I don't care about the actual power plug, I will have to cut it anyway.

    If I haven't been clear enough, I'll try to answer any questions as best I can.

    Thanks.
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    I think its 12VDC. It would be better to buy a 12VDC-4A or greater for the monitor as it draws 3.5. If you use a 3A power supply it will get overheated. If you have a PC power supply you can use it. I am not sure now, but I think its 12V output allows currents up to 8 Amps, for ordinary PC power supplies.
     
  3. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    So it only draws as much as it needs? Cool. Thanks for the advice.
    One more question, the power cable has four cables: red, white, black, and green. What is what?
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    Yes, the display draws as much current as it needs.
    Which cable are you talking about?
     
  5. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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  6. connmannic

    Thread Starter Member

    Nov 23, 2008
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    The power cable for my monitor, it has four wires, not sure what they do, I'm guessing two are grounds, but I can't tell.
     
  7. mik3

    Senior Member

    Feb 4, 2008
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    Well, I am not sure so I wont tell you because if you connect them wrongly you may destroy the display. Whats the part number of the display? Do you have any specifications for it?
     
  8. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    The model number is nis-kdk-ncdl-114, but nothing comes up on google.
    I have no specs, I can't find anything on it.
    Is there a way to test and see what the polarities of the wires are?
     
  9. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    I looked around the site, and it looks like this is what I was looking for.

    red: Positive L+
    white: Mid-wire (center tap) N
    black: Negative L-
    Green: Protective ground PG

    If this is true, how would I wire this into a p4 or molex cable in the power supply, or anything for that matter?
     
  10. mik3

    Senior Member

    Feb 4, 2008
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    Well, this reminds me of the power grid (mains power system) used in USA. Are you sure that the people you asked said that it worked? Post a link where the specifications of the display are.
     
  11. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    They said it worked, not sure how they did it, theirs was slightly different, the voltage was lower and they didnt have this wire problem, it was just a plug. Here is their's:
    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220305108771

    Here is mine:
    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=220309042986


    I have yet to find any info. There are no specs.

    On the bottom of this page is where I found the info for the colors:
    http://www.allaboutcircuits.com/vol_5/chpt_2/2.html#JWi.bibitem

    If the above color codes are right, then what would I wire to the positive and negative of the 12v molex or p4 cable?
     
    Last edited: Nov 23, 2008
  12. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
    0
    My post got deleted. so here it goes again.

    There is a little difference between the two, his has a lower voltage, and there is a plug for the power, not just a wire. so that doesn't even help anymore.

    There are no specs, I'll give you the ebay pages, if that does any good.

    Here is the monitor that I got:

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220309042986

    And here is the one he got:
    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220309042986

    So really now my only question is which wires are which.

    Here is where I found the color codes (at the bottom of the page):
    http://www.allaboutcircuits.com/vol_5/chpt_2/2.html#JWi.bibitem

    Supposing that is correct, what cables would connect to the positive and negatives of the molex or p4 cable? I did some research, and it looks like either would work to power the monitor, as long as the 12v rail has enough amps. The PS I have has 19 amps for the 12v rail, so that should work. I would prefer to use a molex cable.
     
  13. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
    0
    crap, I double posted. Sorry. Thought the first one didn't go through.
     
  14. mik3

    Senior Member

    Feb 4, 2008
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    Where did you find the wire labels you posted?
     
  15. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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  16. mik3

    Senior Member

    Feb 4, 2008
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    Well, I am not from the guys who trust wire colour codes, so I dont put my hand in fire and tell you how to connect it.
    If it burns you will complain to me.
    If you want to connect it according to the colour codes then you will need a bipolar supply (with both positive and negative supplies). The positive voltage will connect to the red wire, zero volts to the white wire and negative voltage to the black wire. Its up to you.
    Personally, I suggest you to open the monitor to see its internal circuitry and see what voltage it needs by inspection.
     
  17. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    Ok I'll do that and et back to you. Thanks for all you help.
     
  18. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    Ok, Good news.

    So I opened it up, and I can now disregard the green and white wires, they lead so some sort of speaker, and have nothing to do with the power. The red and black lead to a switch, then a 12v input. so it looks like all I need is to attach the red to red and black to black on a molex cable and that should work. Tell me if I'm wrong.
     
  19. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Yes you are right. Red wire to positive and black to negative. But to be sure check if there is some labeling on the PCB board for polarities.

    You see, dont trust wire colours :p
     
  20. connmannic

    Thread Starter Member

    Nov 23, 2008
    13
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    Thanks for all your help, I owe you alot. I am using this monitor and a micro atx mb to build a HTPC inside an old imac g3. You just made it possible. Thanks again.
     
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