Even the most basic analogue multimeter can prove to be invaluable when in the hands of an experienced user. Simple measurements of voltage, current and resistance can provide useful information on the state of almost any circuit. What matters, of course, is the interpretation put on the readings obtained. To get the best from such a simple instruments it is not only necessary to select an appropriate measurement function and range, but also to be aware of the limitation of the instrument and the effect that it might, or might not, have on the circuit under investigation.
The diagram below shows the controls and display provided by a simple analogue multimeter.