So I am having some problems with my home theater projector. I am using an oscilloscope to attempt to verify the fans are all working correctly but I am a bit confused by what I am seeing. I was under the impression that fan tach outputs were a square wave equal to the fans input voltage, but having tested all 5 of the fans in this thing that's not quite what I am seeing. The only one that is "different" is this one: Compare that to this one which is more or less what the other four fans look like: Is the fan in question bad? Would that extra "dip" be enough to make the control board think the fan has failed and shut the unit down?
