Powering up sleeping uVAX II

Pete Edwards stimpy.u.idiot at gmail.com
Mon Feb 6 19:00:35 CST 2006

On 06/02/06, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> It is a very bad idea to 'run up' a swtich mode PSU (which this is) on a
> Variac. SMPSUs appear as conatant power loads, as the input voltage
> decreases, the current increases. Some supplies will blow their chopper
> transistors under such conditions.

Having  witnessed the effect of a sustained brownout (I think it went down
to 50V for about 15 minutes) on a UPS-less machine room full of kit with
240V switched mode PSUs, I know that's a no-no. I think the survival rate
was about 20%.

Pete Edwards
"Prediction is very difficult, especially if it's about the future" - Niels

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