It would be difficult to over-emphasize the importance of the advice Dell is giving you.Allow me to re-iterate: (1) Buy a good Volt-Ohm-Meter (VOM). Most of us prefer the analog ones when we can find them. They are more rugged than the digital ones, whose FET input transistors are easily fried by high transient voltages such as those in Kettering ignitions. This in spite of the fact that when they first came out with the digital ones they sold them by claiming the LCD would be MORE rugged than those fragile old d'Arsonoval meter movements. Many people never learn to use a VOM and go on happily operating their equipment, successfully keeping it running. And I respect the art of being able to throw together a bulb and some wire and troubleshoot a system, especially in a road emergency. I am a practitioner myself. But when I am at home I ALWAYS reach for the VOM. After using one a while I think you will, too. (2) Ohm's Law: I=E/R, where I=current, E=voltage, R=resistance. Mnemonic, used by generations of hams, Signal Corps Recruits, and EE majors: the Indian sees the Eagle flying over the River. Most people know this one, but for some reason fail to apply it. A practical example: in this case, one could set the VOM to read voltage. If ANY voltage drop is measured across the switch (which should be zero ohms resistance), it is probably bad and needs to be replaced. (3) Kirchoff's Laws: (a) In any series circuit, the sum of the IR drops must equal the sum of the source voltages. (b) In any parallel circuit, the current into any one branch point of a circuit MUST equal the current out of the branch point. Hope this helps.
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