Flawed thinking?

[jonnyGURU]

I used to think my PSU tests were good because I was using the same kind of load tester factories use to QC their power supplies, but someone at another forums has me thinking that some of the flack I get isn't worth doing these tests anymore......

Your static loads aren't an accurate representation of what a power supply can actually do. I can take a 300W power supply and put a 400W load on it and it's going to work.

True, static loads aren't realistic. But I'm not emulating a PC. I'm wanting to see that a power supply can do what the label says it can do.

It doesn't matter what a label says because you can't differentiate sustained from peak.

Well, sometimes I put a power supply on the load tester and load it up and the voltages go out of spec. Sometimes the voltages bounce as much as .1V every 1/8th of a second. Sometimes the overload or overheat protection kicks the PSU off. These would all be failures in my book. A power supply that can maintain a stable load for as long as half an hour, is a good power supply in my book.

But that doesn't prove how long a power supply can actually last in the real world. Ok, it survived your load test for half an hour, but what about a year down the road after several stressful, sustained loads.

True. But then again... what review DOES tell us how good a power supply is one year down the road? I still think it's better than throwing the power supply into a PC and seeing if it's within 5% of the rail.

And what's this "bounce" you're talking about? You don't have an O-scope, so why shoud I care about this "bounce?"

Well, my SM-268 has an O-Scope output. The readings on the LED's directly coincide with the output to the O-Scope. On an O-Scope screen you have an X and Y coordinate. The X is voltage and Y is duration. As the LED's change, a new voltage (X) is plotted for that moment (Y.) I know the reading is pretty accurate because the fluctuations recorded are actually so "fast" that I can often not see the last digit with my naked eye (on an O-Scope the line would look like nothing more than static. Typically, if I see a fluctuation of .1V every an 1/8th or 1/4 second, I don't think that's a PSU with a strong rail. On an O-scope dialed in to 11~12V and 1/16 second intervals, you'll see a jagged line going up and down between 11.9 and 12V every other lattitude. Graphing this with an O-Scope gives a much better visual than me just "assuming" the rail isn't stable because of what I see, but unless I get some software that I can plug into the O-Scope plugged into my active load tester I'm not going through the trouble. After all.. this is just a hobby. I'm not going to make it into work. I already made that mistake with bicycles.

Well, a PSU that bounces a little bit shouldn't be testimony that it's not good. How a PSU responds to a sudden change in voltage is more important to how it responds to a static load.

Then why did you ask me about the O-Scope in the first damn place?!?!

Well like I said, I can put a 400W load on a 300W power supply and it's going to hold up. So your tests mean nothing. I think you're letting crappy power supplies pass and you're doing a dis-service to enthusiasts. You don't know the definition of "sustained" and "peak" and that's a shame. These are industry wide terms and

And like I said, if I put a 400W load on a 300W power supply.. it's either going to blow up, the voltage is going to take a nose dive or protection is going to kick in. So I don't see your point. I know that some manufacturers rate PSU's by sustained and some rate by peak, but I don't see what that has to do with my tests. If a PSU makes a "500W" claim and that's a peak rating, then the PSU IS GOING TO FAIL. It just is. Is that to say that a PSU that claims to have a 500W capability that passes is one that's rated with a sustained power rating? No. But I'd rather take one that held a steady 12V rail for half an hour at 500W than one that took a dive to 9V before bursting into flames!!!

Whew... Anyhoo.... I just wanted to get that off my chest. I wanted to post somewhere other than that forum because the whole thing was turning into one of those "arguing on the Internet is like competing in the Special Olympics" situations. When I started typing I was seriously contemplating selling off the SunMoon. But I think I'll just go out back and play some darts.

 

[davidhammock200]

As I've said before, you are too polite!

 

[davidhammock200]

As I've said before, you are way too damn polite!

 

[jonnyGURU]

Had to put that "way" and "damn" in there, eh?

 

[mrhemmy]

did that other person just completely contradict himself in every single post?

 

[jonnyGURU]

Eh... It seemed like it, but then again he did make some good points. But there was no satisfying him, though. My testing's flawed. Everyone else's testing is flawed. There's no way to know how good a PSU is going to be one year down the road, so the only way he's going to give a PSU a nod is if his friend's cousin's neighbor had a stable one. I dunno. Fair's fair. I'm not going to see eye to eye with every one.