Any customers who require 1000VDC/750VAC testing capabilities can contact a Keysight Customer Contact Center and reference the service note number.
I contacted Keysight Germany today and had a very nice conversation but they could not offer anything new, except for:
1. There is no problem using my meters for up to 1000 V DC and my meters will all be covered by full warranty, even if something should go wrong.
2. The problem is related to two components on the PCB that are too close in proximity and because of this it requires a design change of the PCB.
There, that's the thing we needed to be told all along. It's a clearance/creepage issue between two components.
Given that information at the start, most of us would have gone, "Ah, OK not a major problem for most practical purposes, I can work around that". It's an engineering explanation of the problem that we can understand and almost instantly answers the questions that most of us would have about the practical implications of this. The only way that could be better would be if they named the components and told us the actual measurements versus the required measurements.
Well, sort of.
The other question that hasn't been answered is whether the clearance distance between the two components in question met the original spec the meter was designed under (or, perhaps, some version prior to that -- implying that no real error was originally made) but somehow doesn't meet a later/current one, or whether it has always been out of spec from the beginning. These are two very different scenarios, and I don't see any real way of determining which is the case.
If it's just a problem with it not meeting the current standard, then using the meter at higher voltages clearly shouldn't pose any issues at all, except perhaps regulatory ones. But if it never met any of the standards, then it raises the question of whether or not the meter will meet its accuracy spec at higher voltages. Saying that it can be used at those higher voltages doesn't automatically imply that it'll meet its accuracy specs at those higher voltages.
Given the totality of the circumstances, and the testing that went into the meter prior to its release (it clearly was characterized with its current design), I suspect we're looking at a regulatory issue only, and that accuracy and safety are not actually impacted by it.
Dear Keysight marketing/lawyers - next time you have an issue like this, instead of messing your customers about with cryptic specification changes that hide the real issue, go and ask your engineers "If you personally were a customer, ignoring anything you might think as one of our employees, what would you want to be told?" and then tell your customers exactly the answers that the engineers asked for.
Yep. This.