Carbon Brush Symptoms There are four major telltale signs that brushes are going bad instead of a switch: Wearing and damaged switches will cause increased off-and-on use as they are used until they eventually don't start up at all.Īs carbon brushes worsen, the symptoms that worsen with them tend to be during operation.
Power Switch Symptoms Power switch symptoms have two major differences from carbon brush symptoms:Īlthough decreased power can be caused by a bad power switch, it is a more uncommon symptom.īad switches more commonly tend to have a hard time starting up, but then will run smoothly and at full power once the connection is made.īrush symptoms tent to cause more symptoms during operation, not just start-up. Start with the carbon brushes since they're usually more accessible, and then- if the brushes check out -take a look at the switch. If that's the case, the best thing to do is to take a look at the parts themselves by opening the tool up. It might be hard to tell whether it's a brush or a switch if these are the only two symptoms presenting. Bad contact to the armature can be caused by brush wear and damage and can cause a decrease in tool performance.
Switches can also cause a decrease of tool power when they have suffered heat damage but not shorted out completely.īetween these cases, a decrease in tool power is more likely to be caused by the brushes. This makes diagnosis difficult at first, but a switch acting like this will quickly get worse by reducing the power performance of the tool even more, making it easier to pin down the cause as time goes on. Sometimes this decrease in power happens without warning signals like off-and-on use. The gradual wear of power switches can sometimes cause a decrease in power that reaches the tool's motor. Wearing or damaged brushes can cause a similar off-and-on use problem, but this is usually because wear, damage, or a "burr" formation is preventing the carbon brush from correctly contacting the armature's commutator. Wearing power switches will cause off-and-on use as their connections wear down, sometimes requiring several pulls of the trigger before the tool starts up. When they first start to go out, switches and carbon brushes can present either (or both) of the following two symptoms : Similar Symptoms Beginning symptoms of wear or malfunction can look the same for both carbon brushes and power switches.
Tool and machine users everywhere can save themselves some extra cash and valuable time when they know what to look for and how to set it fix it on their own. Fortunately, carbon brush replacements and power switch replacements are two of the easiest tool repairs. The steps and descriptions below will help to quickly pin down the cause of the malfunction. We address the issues of carbon brush and power switch breakdowns separately because they are very common part replacements, and because it can be especially difficult to tell which one is the cause of the malfunction.
Because both brush and power switch failures are common-and because both breakdowns present similar symptoms-diagnosing between them when symptoms present can be tricky.įor a full "Diagnosing Electric Power Tools" article-Click here.
Power switch assemblies and carbon brushes are two of the most commonly-replaced power tool parts.