VOM 101

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if your tractor has a brush type generator and / or a breaker ignition system.. might as well leave that sensitive DVM at home and break out the cheap analog meter.. ya know.. the ones with a needle.

sample rate on most consumer grade DVM's is not compatible with brush/noisy lines.. and you can get eratic readings. genny based charge systems tend to use the averaging principle with a vibrating mechanical regulator that quickly alternates between max charge and low charge as the points open and close int he vreg field circuit, with a large value bias resistor across the contacts to provide somefield current with the points are open. those switch in / out spikes really aren't conducive to accurate readings.

add to that a rx1 setting on an analog makes a great points and or condensor tester.

In an energized circuit all you really need for trouble shooting is a sensitive Digital Volt Meter - and theyre all sensitive enuf for tractor work:) . The ohmeter part will get in trouble by being burnt up in a live circuit and even when used right is mostly worthless for measuring low resistance.
http://www.tractorbynet.com/forums/parts-repairs/102900-starter-circuit-problem.html
 
 
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