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techtalk:ref:tools159 [2018/12/16 17:58] – hippysmacktechtalk:ref:tools159 [2024/01/24 22:39] (current) – hippysmack
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 ====== REF: Tools - 159 ====== ====== REF: Tools - 159 ======
-====== Multimeter ======+====== Multimeter (VOM) ====== 
 +See also, [[techtalk:evo:elec01#evoelectrical_system|Electrical Basics]] in the Sportsterpedia. \\ 
 + 
 +A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. ((https://en.wikipedia.org/wiki/Multimeter)) \\ 
 +A typical multimeter can measure voltage, current, and resistance. \\ 
 +Analog multimeters use a microammeter with a moving pointer to display readings. \\ 
 +Digital multimeters (DMM, DVOM) have a numeric display, and may also show a graphical bar representing the measured value. \\ 
 +Digital multimeters are now far more common due to their cost and precision, but analog multimeters are still preferable in some cases, for example when monitoring a rapidly varying value. \\  
 + 
 +A multimeter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy. ((https://en.wikipedia.org/wiki/Multimeter)) \\ 
 +They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems. \\ 
 + 
 +Multimeters are available in a wide range of features and prices. ((https://en.wikipedia.org/wiki/Multimeter)) \\ 
 +Cheap multimeters can cost less than US$10, while laboratory-grade models with certified calibration can cost more than US$5,000.  
 + 
 + 
 +Multimeters are extremely useful and are pretty hardy. ((sifty of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/146604-first-harley-1975-xl1000-caf%C3%A9-project/page42?t=1592463&page=42)) \\ 
 +But using the wrong setting, wrong scale, or performing the wrong type of measurement will at best give meaningless results, and at worst smoke the meter. \\ 
 + 
 +  * Make sure the dial is on Ohms if checking resistance. 
 +  * DC Volts if checking voltage. 
 +  * Amps if checking current (usually also have to change the red test lead to the 10A terminal socket). 
 + 
 +  * Trying to read DC volts while the meter is in AC mode is pretty common (and frustrating). 
 +  * Putting the test leads across 12V with the leads in the amp range will most likely blow a fuse (or worse) which can cause unwanted delays while you fix/replace the meter. 
 +  * When reading resistance (ohms setting) you should short the leads together initially and read what the display says. 
 +    * Subtract this value if the meter cannot be zeroed. \\ (if the meter reads 0.2 ohms with the leads shorted, and 6.4 ohms across a winding, the true resistance will be 6.2 ohms). 
 +  * Make a good contact with the probes when trying to read the display.  
 +    * The values may move a little, but generally they will fluctuate around a meaningful value if the contact point is solid. 
 + 
 +|  See also [[techtalk:ref:svcproc30#reftroubleshooting_-_07|Testing an oil pressure switch]]  |  When checking ohms, first check that the meter \\ reads '0' ohms with leads pressed together. ((photo by Hippysmack))  | 
 +|{{techtalk:ref:svcproc:testing_the_oil_pressure_switch_7_by_hippysmack.jpg?direct&300|}}|{{:techtalk:ref:tools:multimeter_on_ohms_scale.jpg?direct&300|}}| 
 + 
 +====== Probe Mod ====== 
 + 
 +You can buy a couple alligator clips from an auto parts / electronic store and gently crimp the ends over the end of the straight probes. \\ 
 +This will allow you to clip onto pinouts for testing. \\ 
 +You can also lightly wrap electrical tape over the assembly for working in areas where the pins are close to each other so they don't make contact. \\ 
 + 
 +{{:techtalk:ref:tools:multimeter_probe_mod_1_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) {{:techtalk:ref:tools:multimeter_probe_mod_2_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) \\
  
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