The exclamation mark means that a possible difference in earth potential is detected between USB and probe. Fraser warned us about this a few pages ago.
Thanks for the clarification, although this light came on immediately when powering up and without a probe being connected, so there would not have been the conditions present to detect anything at this point?
I thought I posted about the probes not being included, but I can't seem to find my post, so I guess that didn't get posted correctly somehow. Even though it's a bit curious not to include them, especially considering the original price of the unit, the Velleman product videos are upfront about what's included.
Thanks for highlighting this in your previous post. Cheap probes are available on eBay if one is prepared to wait a couple of weeks for them to arrive from the far east, so its not that big a deal, especially at this reduced price, but it just would have been helpful to have had at least one basic cheap probe included with the unit. At the original price I would definitely have expected one.
BTW, I also tend to agree with your comments to 3db. This seems more of a case of a poor product that did not sell at the expected price and the vendor is now trying to shift their stockpile. Maybe I have a dud unit or an early problematic firmware. Whatever the case, this thread has been upfront in pointing out that this device is not without its problems so although disappointing, this was not entirely unexpected. Caveat emptor!