Capacitor replacements

[dognut]

Hello to all. When replacing small electrolytic caps that have polarity markings with lets say orange drop film caps that are NON- polarity marked, how do you install them? Thanks, tom

[dave_gerecke]

Hello dognut,

If the new cap you are installing has no polarity marking, then it shouldn't matter which way the new cap is installed. The reason that you need to respect polarity on an electrolytic cap is that due to the physics of the design, they will explode if they are wired backwards, trust me. The exception to this are non-polar electrolytics. They are actually two normal electrolytics connected backwards to each other, so that there isn't a polarity as far as the outside world is concerned.

Peace,


Dave

[MCampbell]

Originally posted by dave_gerecke
Hello dognut,

If the new cap you are installing has no polarity marking, then it shouldn't matter which way the new cap is installed. The reason that you need to respect polarity on an electrolytic cap is that due to the physics of the design, they will explode if they are wired backwards, trust me. The exception to this are non-polar electrolytics. They are actually two normal electrolytics connected backwards to each other, so that there isn't a polarity as far as the outside world is concerned.

Peace,


Dave

Three thoughts:
Tantalums explode even faster when put the wrong way round!
Also, bipolar electrolyics now tend to use the simpler, cheaper, and (IMO less robust) construction of simply applying the rated voltage in each direction, so that cathode and anode are interchangeable.
Finally, on film caps, the only possible thing you need to look out for when deciding on mounting direction, is the outer foil issue, which, I believe, is well documented elsewhere on this forum.
Cheers,
Matt