Here’s a common problem for people who own small electronic devices, especially power adaptors for effects boxes.
This is an adaptor from my compressor; it outputs a special voltage, has a special plug on the end, and is expensive to replace. I found that out when, as with every other adaptor like this, the extremely thin cable eventually broke at the point where it joins the body of the adaptor. Even if you’re really careful, a few months or years of wear and tear is usually enough to break it because whenever tension is applied to the cable, it is applied to the same place — a join with only very weak stress relief. The cable bends and flexes in all directions, weakens, and after a while either the coating or the wire itself breaks.
When I got the replacement I came up with a nice way of preventing the same thing happening again. I took a cable tie, wrapped it around the body of the adaptor and loosely threaded the power cable in and out of the tie, following it once around the body. Then I tightened the cable tie and snipped it off, as shown in the picture below.
This means that the join between the cable and body (the bit that always breaks) is never subject to tension and never moves, so it doesn’t break. Instead, pulling on the cable just smoothly induces a little bit of tension and only a slight bending at all the points where it crosses over the cable tie. The stress in any one part of the cable is never enough to break it, so it doesn’t break even if you grab the cable by the end and swing the adaptor around the place. And that’s magic.