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Jeff Liebermann <jeffl@cruzio.com>: Nov 14 01:00PM -0800 >Too much information often indicates a not-very-rugged >design, but in cost-critical markets, this is seldom >a deciding factor.   There doesn't seem to be much of a defacto standard in computah power supply labeling or specs. I picked a suitable label from what Google Image Search found: <https://www.google.com/search?q=atx+power+supply+label&tbm=isch> Looking at the various labels, some are overly complexicated, like the one I offered as an example, while others are sparse. The sparsely labeled power supplies are a problem because they will give the voltage and currents, the total power rating, and nothing else. As I demonstrated, just adding up the power for each section results in a total power that is far greater than the total power rating. This leaves the decision for how much power to draw from each section up to the user, with not guidance from the ratings. That's probably not a problem for PC applications. However, users that like to convert ATX power supplies into bench power supplies may have a problem. To make things worse, few of the specs and none of the labels bother to mention the rated duty cycle and operating temperature limits.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

legg <legg@nospam.magma.ca>: Nov 15 07:57AM -0500 On Sat, 14 Nov 2020 13:00:47 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote:   >power supplies into bench power supplies may have a problem. To make >things worse, few of the specs and none of the labels bother to >mention the rated duty cycle and operating temperature limits.   Duty cycle or temperature limits are usually present on the device spec sheet - for commercial product the defacto temp before deratimgs is 40C. Duty continuous unless stated otherwise.   As previously mentioned, safety certified units are stressed with any possible combination of outputs that do not exceed the combined power rating of the unit. For a any test not specifically aimed at the effect of output ratings, the outputs will be loaded to a derating of Prated / Psum, on each output, as a defacto standard 'rated' load.   ATX power supplies are designed to meet the ATX application, which requires only the minimum labeling requirements for certification and is often a captive or single supply chain spec as far as outputs, total ratings and environment/mtbf are concerned.   Refer to the Intel ATX developers guidelines for the copyright owner's standard spec. This is largely a mechanical and interconnection requirement, not an electrical one..   These products are normally limited by the temperature index of their isolation components, fan life and electrolytic cap life. None of those items are on the label, but will be on the mfr's spec sheet. Only the isolation components are safety evaluated. Anything else is subject to single-fault abnormal testing alone.   The only outputs normally expected to handle pulsed loads are those powering motors - fan and disc drive loads typically on the +12.   RL

jaugustine@verizon.net: Nov 14 02:42PM -0500 Hi,   A "Ham" radio friend has an old Knight T-150 transmitter. "R33" , 150 ohm 20W, blew apart due to overload. This resistor is in the +800V circuit, which is the Plate voltage for the Output tubes (6146). He replaced that resistor. I told him to remove those Output tubes and measure the plate voltage. When the transmitter was in "Standby" mode, the voltage was +800V. However, when he switched the Function switch out of Standby, the voltage dropped a lot and he heard a humming sound.   Does anyone have an idea what is loading down the +800V (Output tubes removed)?   Thank You in advance, John N3AOF

"Peter W." <peterwieck33@gmail.com>: Nov 14 12:04PM -0800 Given the age of that device, I have to suspect a leaky cap somewhere. Has it been recapped? There are large number of small-value caps-to-ground starting with 6-46, 47, & 48 (dual-section) that I would start with being as they are electrolytic. But if it has not been recapped, do them all.   Peter Wieck Melrose Park, PA

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: Nov 14 09:32PM +0100 On 14.11.20 21:04, Peter W. wrote: > Given the age of that device, I have to suspect a leaky cap somewhere. Has it been recapped? There are large number of small-value caps-to-ground starting with 6-46, 47, & 48 (dual-section) that I would start with being as they are electrolytic. But if it has not been recapped, do them all.   > Peter Wieck > Melrose Park, PA   Also, if some cap is consuming that much, it must heat up rather fast, and show where the problem is.

Transition Zone <mogulah@hotmail.com>: Nov 14 12:15PM -0800 Dropbox: Drew Houston How I Built This with Guy Raz NPR - Nov 6, 2020 -- https://www.npr.org/2020/11/06/932199300/dropbox-drew-houston

"Peter W." <peterwieck33@gmail.com>: Nov 14 11:47AM -0800 I don't get it. We purchased two Sunbeam extra-large heating pads with five (5) year warranties. One failed in short order and was replaced in short order. The other is going strong after four (4) years. We purchased through Amazon so there would be no nonsense with losing receipts. From what has been discussed here, they seem to fail on an hourly basis and no one invokes the warranty??   Peter Wieck Melrose Park, PA

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