Mystery Laptop Motherboard Component

Discussion in 'Electronics Resources' started by Zoasterboy, Feb 23, 2010.

  1. Zoasterboy

    Thread Starter New Member

    Dec 25, 2008
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    In the process of soldering a new DC jack to a motherboard, I accidentally knocked off a small component that magically disappeared onto the floor below.

    I'm trying to figure out what this component is, can anyone here help me out? There is an identical component in the picture attached. My thought is that it is a resistor, since they are labeled RV1 and RV2 on the board, but I am uncertain. I also can't find any information on them on the web.

    Please ignore the ugly half soldered joints :p

    [​IMG]
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Can you provide a clear closeup of that area, it's a bit hard for me to tell.
     
  3. Zoasterboy

    Thread Starter New Member

    Dec 25, 2008
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    Here's a closer one:

    untitled.JPG
    (Click for larger)

    That's about as close as I can get, it's very small. No markings on it.
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    It seems they are ground resistors for the supply going via the inductor
    From the looks of it you have manage to bridge the pads of the missing component with solder, you better clear that area.
    secondly measure the resistance of the RV1, it will be around in the MΩ range, I think, if possible remove it without damaging it and measure.
    For what it's worth it still might work after cleaning the bridge areas. ;)
    you shud give it a try
     
  5. Zoasterboy

    Thread Starter New Member

    Dec 25, 2008
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    Awesome, thanks. I'll give it a try.
     
  6. sbombs

    Member

    Feb 26, 2010
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    The wiki has an article on reference designators http://en.wikipedia.org/wiki/Reference_designator

    In their chart I found "RV Varistor" I suspect that you may be looking at a Varistor.

    Of course there's no real standardization there but it's a place to start.
     
  7. Zoasterboy

    Thread Starter New Member

    Dec 25, 2008
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    Alright, here's my problem now:

    I have been trying to measure the resistance of the piece but multimeter cannot read miliohms! The thing is too tiny for it to detect. That's just my hypothesis. When set to 200 ohms touching the two probes together reads 0.7, but touching the two ends of the resistor yields nothing!

    From what I've researched about metal oxide varistors (MOVs), the resistance is high at a low voltage and low at a high voltage, suggesting a multimeter won't work in this case. I may just not know what I'm doing though.

    Any suggestions?


    By the way, it's a Dell latitude D505.

    I found a similar discussion started by someone else about the same problem here:
    http://www.daniweb.com/forums/thread276546.html
     
  8. mik3

    Senior Member

    Feb 4, 2008
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    63
    If the nothing is 1, then it is fine since it indicates a resistance greater than 200 ohms.

    What do you read in the megaohms range?

    This component looks more like a capacitor but from the label next to it its a varistor .
     
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