The problem is that cheap meters will give bad readings. For example, reading AC on top of a DC offset voltage can produce incorrect results on a cheap meter. O

The problem is that cheap meters will give bad readings. For example, reading AC on top of a DC offset voltage can produce incorrect results on a cheap meter. Or it can just be broken. An experienced tech can spot the errors and work around these limitations. But for someone trying to learn electronics bad test equipment readings can present a real obstacle.