Here is a trick that kind of falls under the "DUHH!!" category, but it actually took me a while to think of it.
If you spend any time with electronics or any form of music that involves electricity, you will sooner or later need to test a cable. You will need to know that a signal generated at one end is going to make it all the way to the other end relatively unmolested. Once again, your trusty old multimeter is going to get you through this.
In an ideal world you will have access to both ends of the cable and simply attach one lead to the tip of the cable and the other lead to the tip of the other end. Set your Multimeter to Continuity Mode and a reassuring beep will indicate success. Repeat this exercise with the shield, and any other conductors the cable contains. Simple!
But what if the cable is 100ft long? And runs through the ceiling? Into the next room? What will you do?
No need to run out and buy a specialized tool like a Cable Toner. And you certainly don't want to pull the cable through the wall just to get access to both ends. There is an easier way!
Grab your Multimeter and an Alligator Clip test lead and follow me.
1. Make sure to unplug both ends of the cable in question.
2. On one end of the cable, connect the tip and the shield of the cable together using the test lead.
3. Select Continuity Mode on your Multimeter and place one lead on the tip and one on the shield of the other cable end.
4. If you hear a beep, you are golden! The cable is conducting.
5. To be safe, remove the test lead from the far end of the cable. attach the multimeter to the tip and shield of the cable once again. You should not hear a beep this time. If you do, your cable is shorted!!! This is BAD!!!
(If your cable has 3 or more conductors (XLR, Stereo Phono) you can still use this trick. Just attach the alligator test lead to each conductor in turn and repeat the test process.)
This trick has saved my butt more times than I can count! Enjoy!