「in case」の使い方

For a few days, I want to talk about how to use the word "case". Today is the phrase "in case". Here's the definition from Eijiro on the Web:

in case 念のため、万が一（～する場合｛ばあい｝）の用心｛ようじん｝に、万が一［もしもの場合｛ばあい｝］に備えて、何かあるといけないので、～するといけないから、万一｛まんいち｝～の場合｛ばあい｝には◆ifよりも口語的
・(Just) in case you didn't know yet, his website is gone for good. : すでにご存じとは思いますが、一応念のために言うと、彼のウェブサイトは永久閉鎖されました。

"In case" is used like this:

in case __(a situation with a subject and verb)__, __(something you do, often beforehand, to prevent something bad from happening)__.

• 事前 (じぜん) (n,adj-no) prior; beforehand; in advance; (P); (definition from Edict)
• その後 (そのあと) (n-adv,n-t) after that; afterwards; thereafter; (definition from Edict)

× In case my headphones break, I have to buy a new pair. <- this is done afterwards, not before
× In case of I break my headphones, I have a backup pair. <- I'll talk about "in case of" another day.
× In the case of I break my headphones, I have a backup pair. <- I'll talk about this in another post, too.
○ In case I break my headphones, I have a backup pair. <- My headphones might break. If they do, I have a backup pair that I can use.

Read this post once more, just in case.

• Just in case. 念のために。／万が一の場合に備えて。