Replacing failed powersupplies on qbus PDP-11s

I wouldn't go that far, for all I am one of the people least likely to use or trust a simulation. I would say that a simulation is only as good as the model and the data, and that in most cases you haven't much of a clue about how either of those relates to reality. For example, a circuit similation may only be meanigful if you correctly handle the inductance of all the wires and the cpaactiance between them. Something that you might well not know accurately enough!. If curse correctly, simulation can be useful. IMHO one of the frw correct ways (if not the only way) to use simulation is : 1) You have a real physical system that you do experiments on and collect real data 2) You simulate the same system under the same conditions and simulate the same experiements on that system 3) If the results agree, then it is likely (although not certain) that the simulation is an accurate description of the system and that tghe theory you used to produce the cimulation also applies to the real system But if they results don't agree then either you have experimental measurement errors, a bug in the program, or more interestingly the theory doesn't apply to the real system, perhpas there is some other effect you've neglected. In which case you need to do more investigations. -tony