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  • #2150501

    using the multimeter

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    by koggerson_dicky ·

    At what voltsge will you set the multimeter to test the cpu fsn

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    • #2926179

      Clarifications

      by koggerson_dicky ·

      In reply to using the multimeter

      Clarifications

    • #2926173

      Never heard of a fsn.

      by cmiller5400 ·

      In reply to using the multimeter

      But if you mean FAN, then 12vdc

    • #2926172

      Set it at

      by rob miners ·

      In reply to using the multimeter

      20 Volts DC

    • #2926165

      Just remember that Voltage is only part of the requirement

      by oh smeg ·

      In reply to using the multimeter

      You also need Wattage or Amperage as you can have Voltage without and Current and still not have the Fan working. So you need to test the Voltage and Current if you have a Multimeter that has the Current Option.

      Using the Multimeter set to 20 V DC for any computer work is sufficient for all Voltage Testing.

      Col

    • #2925784

      Multimeter usage

      by mjd420nova ·

      In reply to using the multimeter

      You need to use the 20 volt DC range, and measure the voltage with and without the fan plugged in. Also measure the AC too, this will give you an idea of how well the power supply is filtering the DC voltage. The AC reading should be less than 100 millivolts AC, if it’s more, replace the power supply.

    • #2925777

      Careful with the probes

      by thechas ·

      In reply to using the multimeter

      I know that we suggest using a DMM often. It is a very good trouble-shooting tool.

      That said, unless you know what you are doing with the meter, it can be difficult to understand the data.

      Major meter manufactures like Agilent, Fluke and Keithley all have usage guides that you can download and review.

      Good motherboard manuals or web sites like Hardware Book
      http://www.hardwarebook.info/
      Provide information on connector pin-outs and expected voltages.

      Now, the standard probes that come with most meters are useless for all but the most basic of tasks.

      I use either micro-grabbers or fine point probes most of the time.

      The most important thing is to make a good connection without shorting the probes to nearby connections.

      Most CPU fans have 3 lines. Power (usually 5 volts) Ground (return) and Tach.
      The tach output is a pulse directly proportional to the fan speed. Most cheap DMMs cannot read this signal properly.

      In all the systems I’ve worked on, I have only seen the fan power connector fail once.

      If your CPU fan does not spin, or spins slow, the first thing to check is does the fan itself spin freely when power is off.
      If the fan blade does not spin free, then the bearings are shot and you need a new fan.

      Chas

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