Thanks, Matt, for the insight. Sounds like it would be a little much then to try to finagle a fan into the enclosure for what little it might actually do. Thanks again to everyone -
--- On Sun, 5/16/10, Matt Syson <[email protected]> wrote: From: Matt Syson <[email protected]> Subject: Re: NEOTEK: Rebuilding a power supply; parts question To: [email protected] Date: Sunday, May 16, 2010, 5:41 PM Hi I would tend to agree with Ike in that unless the transistors and rectifier (particularly) get more than a comfortable 'hand hot' then it is not worth installing a fan, which is itself more likely to fail than a 'moderately warm' piece of kit. Fuseholders are an interesting case in that their operation depends on them getting hot (to melt the wire inside during a fault) but that it does get warm in normal use which tends to encourage degradation of the terminals which in turn makes them hotter and prone to failure. Poor assembly and soldering is inexcusable although what I remember of the unit I worked on a while ago the mechanical assembly is a little 'strained' possibly encouraging failure unless carefully assembled. A bit like CSI, some interesting (yawn) effects come to light in gear left on for years on end which in turn suggests better ways of doing things. As a useful 'dodge', if you have a known stable mains supply you can investigate running the supply on a higher mains tapping (if possible) so that less power is wasted as heat in the supply. The only downside is that if your mains 'dips low' then you may get some mains 'ripple' appearing on the audio (120Hz in the USA). Certainly worth a thought and cheaper than a fan. Matt S Ike wrote: > Guys, > It's been my experience that these supplies, at least the PS-3, do not >run anywhere near hot enough to need fan cooling. 100% of the heat damage that >I have seen has been due to bad solder joints on mainly the fuse holders and >the pass transistors causing specific connections to heat up. All a fan will >do in that case is possibly extend the MTBF. Some of the supplies I have >rebuilt are in their 7th and 8th years of nearly constant use. Best > Ike Zimbel > Zimbel Audio Ltd > 416-720-0887 > www.zimbelaudio.com <http://www.zimbelaudio.com> > Sent from my iPhone > > On 2010-05-16, at 10:36 AM, Mike Thompson <[email protected] > <mailto:[email protected]>> wrote: > >> Awesome, thanks guys. >> >> Would it be even better to go a step above and install a quiet fan into it? >> Either way this is going to be racked with at least 1U of space open top and >> bottom. >> >> >> --- On *Wed, 5/12/10, Matt Syson /<[email protected] >> <mailto:[email protected]>>/* wrote: >> >> >> From: Matt Syson <[email protected] >> <mailto:[email protected]>> >> Subject: Re: NEOTEK: Rebuilding a power supply; parts question >> To: [email protected] <mailto:[email protected]> >> Date: Wednesday, May 12, 2010, 4:39 AM >> >> Hi >> The main killer of power supplies in the long term is HEAT. >> Electronic parts are 'happiest' at around 20 - 25 Centigrade and >> the closer you can keep ALL the parts to this the better. Of >> course to achieve this involves decent airflow and intelligent >> placing of parts so that the ones that can tolerate a little more >> heat are placed in a suitable position. >> Overrating of particularly the 'pass' transistors and the main >> rectifier is 'cheap' insurance. In a 'power one' 13 Amp supply >> module they run 2N3055 transistors at about 2 Amps per device >> which is sensible and I have never seen any failures of these >> devices out of what must be over a thousand units. Rectifiers and >> occasionally transformers are a different issue. >> Remember that heatsink temperature is lower than the temperature >> the transistors (and rectifiers) get to so if the heatsink feels >> too hot to touch (or hold comfortably) then the transistors are >> probably being run a bit hard. Here, having multiple devices >> helps spread the strain as the interface between the transistor >> and the heatsink, using an insulating washer can allow >> significant difference. Make sure you have effective thermal >> compound in there and the screws are tight. >> With shortage of studio space and the fact these supplies are >> silent it is tempting to hide them away somewhere. They MUST have >> good cooling airflow. >> Matt S >> >> Ike wrote: >> > Hi David >> > No daggers from this quarter! The only thing I would add >> is that what I have found with over a dozen PS-3's that I've >> known is that the failures are almost entirely due to assembly >> problems. IOW the parts that fail tend to do so because they >> weren't soldered and/or mounted properly at the factory. Once >> these things are corrected they can and do run for years without >> any trouble. >> > Best >> > Ike Zimbel >> > Zimbel Audio Ltd >> > 416-720-0887 >> > www.zimbelaudio.com <http://www.zimbelaudio.com> >> > Sent from my iPhone >> > >> > On 2010-05-11, at 11:29 PM, David Butler <[email protected] >> <mailto:[email protected]>> wrote: >> > >> >> As a former power supply engineer I will weigh in here, all >> the while watching my back for daggers! >> >> >> >> :-) >> >> >> >> In general, PSU designers do NOT underrate components enough, >> IMNSHO. This is why so many power supplies dies early, untimely >> deaths. The capacitors in particular, tend to bake. If higher >> temperature caps can be found, so much the better. In general, >> going up a little in voltage rating on caps is OK, SOMETIMES >> going up in value is OK too, depends on the design. The idea all >> around is that heavier is GENERALLY better. You don't want to go >> extremely high on capacitor voltages: they are happiest on a diet >> of 50% or so of their nominal ratings. >> >> >> >> The power transistors can sometimes benefit from having higher >> voltage, power and current ratings, as long as everything else >> (gain especially) is the same. Personally I like rectifiers rated >> at at least double, if not triple, the PEAK voltage in the >> circuit. Again, rating for higher temperature handling rarely hurts. >> >> >> >> If the supply in question lasted a long time with no problems, >> there is no fault to be placed on using exact replacements >> either. My own take is to be conservative by going for heavier >> parts if the costs are not excessive. >> >> >> >> Just my 50 cents... >> >> >> >> db >> >> >> >> -- David 'db' Butler >> >> AV Wizard, Audio Guru & Team Leader delivering exceptional >> >> on-time & under-budget results with cutting edge technologies. >> >> >> >> >> >> Quoting Mike Thompson <[email protected] >> <mailto:[email protected]>>: >> >> >> >>> I have a question regarding parts replacement - >> >>> >> >>> i have a tech who has looked at my Series 1E power supply and >> told me he could rebuild it with no problem, but I wanted to >> make sure before I handed it off to him if there were any parts >> that needed to be specific values (equal to or greater), >> anything that should specifically be improved upon when >> rebuilding, how to make it compliant to the standard, or any >> other tips to make sure I get the most out of it. I know some >> of you guys had rebuilt them and I figured this was the best >> place to ask. Let me know. >> >>> >> >> >> >> ------ >> >> >> >> View the list online at: >> http://www.mail-archive.com/[email protected] >> >> >> >> You can unsubscribe at anytime by sending an email to >> mailto:[email protected] <mailto:[email protected]> >> with "unsubscribe neotek" in the message body. If you have any >> difficulties, or questions --please send an email to >> mailto:[email protected] <mailto:[email protected]>. >> >> >> >> The Neotek list is lovingly hosted by Catapult Web. Remember >> that any message or reply sent to the list will be automatically >> forwarded to all subscribers. >> >> >> >> Vive Le Neotek! >> >> >> >> Thanks. >> >> >> > ------ >> > >> > View the list online at: >> http://www.mail-archive.com/[email protected] >> > >> > You can unsubscribe at anytime by sending an email to >> mailto:[email protected] <mailto:[email protected]> >> with "unsubscribe neotek" in the message body. If you have any >> difficulties, or questions --please send an email to >> mailto:[email protected] <mailto:[email protected]>. >> > >> > The Neotek list is lovingly hosted by Catapult Web. Remember >> that any message or reply sent to the list will be automatically >> forwarded to all subscribers. >> > >> > Vive Le Neotek! >> > >> > Thanks. >> > >> ------ >> >> View the list online at: >> http://www.mail-archive.com/[email protected] >> >> You can unsubscribe at anytime by sending an email to >> mailto:[email protected] <mailto:[email protected]> >> with "unsubscribe neotek" in the message body. If you have any >> difficulties, or questions --please send an email to >> mailto:[email protected] <mailto:[email protected]>. >> >> The Neotek list is lovingly hosted by Catapult Web. Remember that >> any message or reply sent to the list will be automatically >> forwarded to all subscribers. >> >> Vive Le Neotek! >> >> Thanks. >> ------ View the list online at: http://www.mail-archive.com/[email protected] You can unsubscribe at anytime by sending an email to mailto:[email protected] with "unsubscribe neotek" in the message body. If you have any difficulties, or questions --please send an email to mailto:[email protected]. The Neotek list is lovingly hosted by Catapult Web. Remember that any message or reply sent to the list will be automatically forwarded to all subscribers. Vive Le Neotek! Thanks.
