Edit Article

How to Check a Resistor

http://www.wikihow.com/Check-a-Resistor
Resistors are probably the most common electrical component made, and the easiest to test. They are also one of the least expensive components. They are typically small tan(other colors such as dark brown or light blue are also possible) cylindrical devices with colored bands painted around them, but other forms include white ceramic rectangular boxes, circular metal/black carbon mechanisms, or even open air wire coils.

Steps

  1. Image titled Check a Resistor Step 1
    1
    In order to test a resistor, it is important to first disconnect one lead from the circuit .. it won't matter which one.
  2. Image titled Check a Resistor Step 2
    2
    Next, obtain an electrical meter capable of measuring resistance. This is typically called an ohm-meter, and is almost always a function of a standard multi-meter.
  3. Image titled Check a Resistor Step 3
    3
    You will next need to determine the rated value of the resistor. With the colored band variety, you will need to look up each colored band and determine its meaning. The first two bands will be single digit numbers, followed by the third band which is a multiplier. The fourth band will be an accuracy rating for the device. For example: band1=1 band2=0 band3 = x100 band4 = 5%; would mean 1000ohms +- 5%. The ceramic and wire varieties will often be labeled in ink with a value. The carbon/metal variable resistors will not usually have a stated value labeled, but you can look for a smooth transition as adjustment is made to the wiper position.
  4. Image titled Check a Resistor Step 4
    4
    Set your meter to an appropriate range(nearest value higher than the expected measurement), and connect the leads(polarity will not matter).
  5. Image titled Check a Resistor Step 5
    5
    Compare your reading with the value determined above. It should be near the given value and within the tolerance range.
  6. Image titled Check a Resistor Step 6
    6
    If it is, its likely good - otherwise not.

Community Q&A

Unanswered Questions
Show more unanswered questions
Ask a Question

Warnings

  • Use caution when working on electrical circuits. Even battery powered devices can produce and store potentially lethal voltages(consider tazers - they are battery powered hand-held devices - it can happen with many circuits!).