Dave, I was trained as a chemist but that is a long time ago (30 years). I've been led astray by a Burroughs mainframe and have earned my money in IT ever since with one exception: in 2012 I taught chemistry for 2 months. Oh boy, secondary school did change a lot in 40 years! -----Oorspronkelijk bericht----- Van: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] Namens Dave McGuire Verzonden: zondag, september 2013 1:43 Aan: hecnet at Update.UU.SE Onderwerp: Re: [HECnet] Alpha Server 1200 p/s schematics No problem. A chemist, eh? Very cool. I have the privilege of working with a chemist now; she and I are collaborating on a fluorometer project. Fun stuff. -Dave On 09/28/2013 04:45 PM, Hans Vlems wrote: Thanks Dave *Van: *Dave McGuire *Verzonden: *zaterdag 28 september 2013 21:23 *Aan: *hecnet at Update.UU.SE *Beantwoorden: *hecnet at Update.UU.SE *Onderwerp: *Re: [HECnet] Alpha Server 1200 p/s schematics It's a capacitor that is rated to be placed across (hence 'X') the AC line. They are usually applied in just that situation, and are basically for filtration. However, their secondary purpose is as a "sacrificial" component to protect the rest of the power supply in the event of a large differential glitch between the two AC lines. One must never place a "regular" (i.e., non-X-rated) capacitor in place of one, though. Capacitors designed for such duty are usually physically marked with an 'X'. -Dave On 09/28/2013 02:49 PM, Hans Vlems wrote: I'm just a chemist so help me: what is an X capacitor??? *Van: *Dave McGuire *Verzonden: *zaterdag 28 september 2013 14:56 *Aan: *hecnet at Update.UU.SE *Beantwoorden: *hecnet at Update.UU.SE *Onderwerp: *Re: [HECnet] Alpha Server 1200 p/s schematics On 09/28/2013 08:24 AM, Rok Vidmar wrote: I' m thinking of repairing the damaged unit but need schematics for that. In fact, you don't. Open it up, replace the electrolytes. Near them you may find a blown small element which is not needed really. The 'X' capacitor? Actually I'd not want to run a big power supply without that. They're usually not difficult to find, or to replace. -Dave -- Dave McGuire, AK4HZ New Kensington, PA -- Dave McGuire, AK4HZ New Kensington, PA -- Dave McGuire, AK4HZ New Kensington, PA