Re: [CAD_CAM_EDM_DRO] Re: How do I check the MOSFET's in my stepper driver

washcomp wrote:

>Thanks Jon,
>
>I'll check the transistors. (fuse is a small sealed fast-blow
>ceramic, so I don't think I'll get anything by inspection. Any idea
>how fast the in-line fuse (external to the drive) should be?
>
>

A properly sized fuse in AC motor applications, where a starting surge is
common, should last several years at least. A properly sized fuse in
electronic applications, even where a small capacitive surge hits it on
every power cycle, should last decades without false blows. In a current-
limited case like a stepper drive, a slow-blow fuse might be a good idea.
Something like the MDL series.

In this kind of equipment, nothing that you do in normal situations, and
even
some abnormal ones, should blow the fuse. The fuse's main purpose is to
prevent fires and circuit board tracks from burning off the boards. It most
certainly has no way to cut power fast enough to save semiconductors!

Jon