Quote:
It's a voltage thing, IIRC. At 110v, there's no whine. At 240v, there is. [...] The PSUs that we used in the pre-production units worked fine, but they changed something for the production run, and only tested it in the US.

Yes. It's also related to Tman's point about power supplies not working properly if the output load is too small: at 110V input, the Central isn't too small an output load, but at 240V in the UK (and 230V in Speedy's native Germany, which incidentally I looked up in Schott's Original Miscellany, which I'll now be sending back, as it's clearly been misadvertised as containing solely useless information) the Central is too small an output load, and the PSU goes into oscillation and literally whines.

Adding a dummy load is another way of solving the problem: Richard-the-second tried jerry-rigging a big old winchester to his Central, and the power-supply did indeed stop whining, but unfortunately he couldn't find an old winchester that didn't whine worse. I think he eventually solved the problem using a bunch of 5W lowish-value resistors, but that's hella inelegant.

Peter