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  1. #1
    3 Star Lounger
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    Is there a "tester" for laptop CPU fans?

    I have an old Dell C640 that I only use to play my music on. It was giving me problems with staying on than last week the temperature dropped and it worked great. The last two days the temperature have been going up again. Last night the problems started. The fan is 5V 1.5A with on of those super small 2 pin conductors. I was thinking about getting enough AA batteries together to get me to the 5V and test it that way.

    Thanks

    Marc

  2. #2
    5 Star Lounger RussB's Avatar
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    Battery power will work to test it, also you could do a continuity test with Volt-Ohm meter. Also verify that there is 5 VDC on the MB connector. Are you sure that it is not a variable speed fan?
    Also can you try to 'kick' start it with a pencil eraser?
    I have an older PC power supply that is used for testing.
    It has these:
    Black = common (0v)
    Red = +5v
    White = -5v
    Brown = sense wire (connect to orange)
    Orange = 3.3v (do not use, just connect it to the brown wire)
    Yellow = +12v
    Blue = -12v
    Gray = LED (go thru a 330 ohm resistor)
    Green = power ON (can just be attached to a black wire or put thru a switch).
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  3. #3
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    Quote Originally Posted by Check Marc View Post
    I have an old Dell C640 that I only use to play my music on. It was giving me problems with staying on than last week the temperature dropped and it worked great. The last two days the temperature have been going up again. Last night the problems started. The fan is 5V 1.5A with on of those super small 2 pin conductors. I was thinking about getting enough AA batteries together to get me to the 5V and test it that way.
    Marc,
    Hello... If you open the case and look at the fan it should be able to be spun by hand with little resistance... you should be able to feel any "Looseness" and if the bearing or sleeve bearing is damaged ...It will feel rough when you turn it ...As far a batteries ... If indeed the fan takes 1.5 Amps your going to need a lot of "AA's" to run it for a while ...they have the voltage necessary, but not much current capability. If you have a multi-meter hook one side of the fan in series with it and check the current draw... Also feel the fan after it has been running awhile and see if it's burning hot... Regards Fred
    PlainFred

    None are so hopelessly enslaved as those who falsely believe they are free (J. W. Von Goethe)

  4. #4
    Bronze Lounger DrWho's Avatar
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    Cool

    Ahem!

    In 30+ years, I've never seen a 5v fan in any PC. They are always 12vdc and some are controlled by the motherboard, sensing the temperature of the CPU chip. Those fans will be either three wire or four wire, but never a two wire. The OEM fan for my AMD CPU is a four wire fan.
    But whether it's two wire, three wire or 4 wire, they are always 12V.

    The finger method is my all time favorite to test whether a fan is turning freely or not.
    But watch it while it's running. Then shut down the PC and see if the fan stops abruptly or spins down gradually.

    I've taken CPU fans that could hardly even be turned by hand, cleaned them and re-oiled the bearing with some very light machine oil, (NOT 3 In ONE) worked the oil in by hand and put them back in service.

    I took one 'Thermaltake' fan that was almost ten years old, and screaming like a banshee, and cleaned and re-oiled it and it's still running today, as quiet as a mouse blowing bubbles in a feather bed. (that's quiet!)

    Do a little more investigation and see what's really going on with that fan. OK?

    Cheers Mate!
    The Doctor

    PS:

    This was a heat sink that was completely blocked by lint and dirt. The fan was running wide open to try to cool the cpu.
    The customer was complaining about all the noise the fan was making. After a good washing to clean the heatsink and carefully hand cleaning the fan blades, and re-oiling the bearing, the fan ran nice a quiet again.

    Under the center of that stick-on label is the main fan bearing. Don't ever remove those labels. They will never stick again.
    Just put a small hole in the center of the label and stick the tip of a pocket oiler into the hole and squirt in a couple of drops of oil.
    Then spin the blades by hand to work the oil into the bearing, power it up and make sure it spins up easily and runs quietly.
    Job done.
    Experience is truly the best teacher.

    Backup! Backup! Backup! GHOST Rocks!

  5. #5
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    "Is there a "tester" for laptop CPU fans?" hope this help make sense of the 5V fan.

  6. #6
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    There ARE indeed 5V fans. You can buy them even. (Google '5V fan'.)
    Some of them are used in video cards to cool the vpu-heat sink.
    I think 5V fans consumes far less than 1.5A. Most likely it is 0.15A (150mA).
    I have a few such fans using same color wires, hard to know which is the 5V wire and which is 0V. (Proper polarity depends on the connector as protection.)
    If the fan is still in the circuit board of the PC, use a Voltmeter, or DVM, to probe the connector pins, all while the PC is powered on. Find out which wire is positive 5V. Mark the wire. Then you can pull out the fan connector, and the fan too if you prefer.
    Now use a USB 5V AC adapter/charger as 5V source. Or, as you say, use enough battery to get to 5V (4.5V is fine; it is 3 AA in series. 6V, 4AA, is also fine too for a short-time test).
    Test the fan that way.
    Be careful of polarity.
    Innocent me once burned 2 up using 12V because I thought they were 12V fans. (Old, (2001?) Dell desktop PC used two 5V fans in the power supply.)
    Then I reversed polarity when testing another. Burned up that new one too.
    Apparently, some fans do not have polarity reversal protection. 5V fans usually are small. Maybe it skips polarity protection because of space issue.

  7. #7
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    I found a a new one on eBay for 9 bucks. By the time I tear the thing apart to test it I can but the new fan in an get it done. If it's not the fan then I start looking else where.

    Thanks,

    Marc

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