Are your Capacitors Installed Backwards?!

I'm not a heavy electronics guy. Just a dabbler of things that won't set my hair on fire.

If you're like me that usually means guitar circuit wiring or maybe the occasional amplifier repair.

Because of that I had no idea that capacitors in fact have a polarity.

But as I am discovering, and even more startling, the chassis (ground) markings on the majority of them are marked incorrectly!
So, even if you DID know about the polarity you cannot rely on the way caps are marked anyway.

Why Should You Give a Poop About This?

Well, consider this.
If capacitors are installed backwards they can introduce noise to the circuit.

If you've been going nuts trying to get rid of a persistent hum and you've done all the usually grounding techniques, this just might be worth investigating.

Here is an excellent video on the subject by a very competent technician (interesting YouTube channel too)

Caveat - the one pictured is a polystyrene capacitor, not polarised. Electrolytic and tantalum ones are and the polarity is clearly marked on them. All others (that I know of) like Mylar, metal film and ceramic are not polarised.

I should have added that you will only find polarised (Tantalum or electrolytic) capacitors in active tone controls. Every Westone I've ever seen with passive tone controls uses a Mylar one, makes no difference which way round it goes.

I had always assumed that it didn't matter which way it went in. [Insert lewd joke here]

I can't comment on your post except to say that the take away of the video is that you can't be sure of any capacitor, marked or not.

So I would say that it's wise to check to be sure, especially if it's critical. And not everyone may have your experience or even the ability to identify the cap's material eh?

True - some Tantalum caps look a lot like ceramic ones but they do have polarity markings. You can check  the type by looking at the selection on somewhere like Rapid Electronics but essentially if it isn't electrolyic, Tantalum or Aluminium (a new one to me and I've been playing with electronics for over 40 years, designed and built my first synth / sequencer at 18. RIP the texas instruments SN 76477N) it isn't polarised.

Addendum - capacitors can leak with age (I've fixed dead amps just by replacing the output smoothing capacitors). If the capacitor is the problem re-orienting it shouldn't make a difference, replacing it might

Mylar (preferred) and Polystyrene capacitors are 'non-polarized' , so the only wrong way to install them is so their reference code is facing downward. Just like 'carbonite' [carbon] resistors make the best 'signal path' resistors.