[rescue] VME questions
Curtis H. Wilbar Jr.
rescue at hawkmountain.net
Wed Jan 29 16:16:07 CST 2003
>Date: Wed, 29 Jan 2003 14:41:02 -0700
>From: jodys at helluin.org
>To: rescue at sunhelp.org
>Subject: [rescue] VME questions
>1) I'm presuming that I need a load to test the power supply
>(little label inside says 10% needed). There are four fans
>on the tray; 2 are DC12V at 0.45A and 2 are DC12V at 0.26A.
>The power supply is (according to the sheet that came with
>the chassis is 500W). The label on the back lists 115VAC at
>10amps. Are the fans enough load for the supply? My electronics
>knowledge is nil, so I'm at a loss on how to calculate this.
>Also what happens to the supply if I don't provide enough
>load? Is it a quick, "flip-the-switch-bye-bye-magic-smoke" or
>a more long term failure?
I would say the fans are not usually enough, and in my general
experience if a power supply needs load to regulate, it needs it
on the +5V line, not the +12V line. So you need some sort of
If you have an old hard drive or two kicking around, it may be
enough load (especially if they are 5.25" drives).
Most of the time I've tried power supplies without load, they
hover close to 0V w/o a load... I've never seen one smoke because
of no load so I can't claim if that could happen or not, but I
>2) The card-cage seems to be fitted for double-depth cards (I'm
>3) What should I do with this? I've grown rather fond of the
>rescue list - http://www.sunhelp.org/mailman/listinfo/rescue
Sorry I can't comment on #2 and #3... I'm not a VME person.
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