----- Original Message ----- From: "Didier Derny" <firstname.lastname@example.org> To: <email@example.com> Sent: Saturday, February 04, 2012 2:44 PM Subject: RE: 110V 60Hz / 220V 50Hz power supply > After the failure of the 9090/9060, commodore had to redesign a part of > the power supply to sell them in Europe. Well, since they were 110V power supplies I imagine that they _would_ have to redesign them for Europe and elsewhere ;-) > They all failed the same way when powered with 50Hz. "All" being an unknown number >= 2 ? > When we checked the drive, we had 7.5v instead 5V Presumably a failed pass transistor but 7.5V sounds a little low, perhaps suggesting excessive current draw elsewhere. > I don't know how many were affected, the failing one were 2 pre series. > It was not officially sold when we received them. So these were production US models that Commodore had shipped you for evaluation? > I don't remember very well, but a chip in the power supply was working > fine at 60Hz And failing at 50 Hz. Do we _know_ that some of these early drives did not also occasionally fail at 60Hz and it was just a design/quality issue? I guess we will never know exactly what the problem was, but in any case I still think that in general you're pretty safe running this sort of equipment through a step-down transformer of decent quality and appropriate rating as long as you keep in mind that the transformer in a _linear_ supply will run a little warmer; if it is marginal to begin with, has no thermal protection and is loaded to or beyond its limit it may indeed overheat and fail but unless there was a primary to secondary short I don't see how that could damage the regulators. Interesting though. A switching supply is of course completely unaffected by line frequency. m -----Message d'origine----- De : firstname.lastname@example.org [mailto:email@example.com] De la part de Gerrit Heitsch Envoyé : samedi 4 février 2012 17:59 À : firstname.lastname@example.org Objet : Re: 110V 60Hz / 220V 50Hz power supply On 02/04/2012 05:38 PM, Rainer Buchty wrote: > On Thu, 2 Feb 2012, Groepaz wrote: > >> nah. the fact that many PSUs actually contain transformators that can >> be used for both 110/220v mains (and thus 50/60hz) simply by rewiring >> should tell you that there is no such problem :) > > That doesn't contradict Gerrit. The point here is that the transformer > was designed to work in both modes, therefore not being designed to just > (or, today, barely...) fulfill its task. You just need to use a 50Hz Transformer and design it so that it will be able to deliver enough power when run at 60Hz. Problem solved. > (But, yes, I'm running quite some 120V/60Hz equipment from 240V/50Hz > mains with a 240V/120V transformer in between, and so far never > experienced any problems.) So do I, but I always keep in the back of my mind that there could be a problem, especially if the transformer in question is loaded close to its specified maximum output. Gerrit Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2012-02-07 05:00:08
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