George, I too have an old Simpson 260. The last time I tried to use it, it wouldn't work. I suppose the switch contacts are corroded from lack of use.
The reason the old analog units had a zero adjustment wasn't so much to allow for the lead resistance as it was to compensate for the battery condition. They don't have a real stable current source (I think it's just a resistor), so the zero would be all over the map.
Something to be aware of with digital units is that the "continuity" or "diode check" scale is NOT a resistance measurement! It actually displays VOLTS, not OHMS. The reason for this is that a good diode has a forward bias voltage of around 0.7 volts. A lot of folks use the diode check range, see a reading of less than 1.0 and assume the resistance is zero. NOT SO! When in doubt, double-check the actual resistance.
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Today's Featured Article - Listening to Your Tractor - by Curtis Von Fange. Years ago there was a TV show about a talking car. Unless you are from another planet, physically or otherwise, I don’t think our internal combustion buddies will talk and tell us their problems. But, on the other hand, there is a secret language that our mechanical companions readily do speak. It is an interesting form of communication that involves all the senses of the listener. In this series we are going to investigate and learn the basic rudimentary skills of understanding this lingo.
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