Super Flower 1200W ATX PSU powerline noise ?? - Page 1
Forum section: electronics / general

author: MathWizard
author_rank: Super Contributor
timestamp: December 12, 2024, 06:00:01 pm
content: I had an old 850W PSU, and there's about a 14W LED bulb plugged in, on the same circuit as my PC and stereo. It never really flickered before.But then I got a new Super Flower Leadex 1200W 80+ Platinum PSU, and as soon as the PC is running, the bulb flickers. On a 3.5D DMM, the voltage goes from about 117.3VAC to about 116.3VAC, when the PC is on. It moves up/down a bit, with the PC on or off though.The flickering is more like a few times a sec/ or not much faster. It's fairly annoying, I'll try some other bulbs. I guess there's not much else I can do, these bulbs are too hard to take apart anyways.So is it bad light bulb design or bad PSU design? How much sub 60Hz noise is allowed ? I'm tempted to drag the scope over had have a look.Geez these are safety plugs tho, it was a pain to get DMM probes in the slots, and to find contact.

author: thm_w
author_rank: Super Contributor
timestamp: December 12, 2024, 10:48:43 pm
content: Is it a quality brand LED bulb?Interesting that it got worse, you'd think the high quality PSU would have good PFC and not cause large draw. But, did you just change the PSU or does your PC now draw a lot of power too?

author: MathWizard
author_rank: Super Contributor
timestamp: December 13, 2024, 01:31:49 pm
content: No it's the same PC, and happens when idling, and together with the stereo, they probably use under 150W. I never paid attention to the light when I was gaming, but those games don't use that much power either, (my PSU is overkill, but not at the great price I got it, and it's for an i9-14000KF and RX 7900 xtx)The bulb is a non-dimmable 8.5W type, not a big brand name but from a big supermarket, so legit. Of the couple I tried, they both flicker. I tried a working Sylvania 13W compact florescent, it flickers a bit, but not nearly as bad as those LED's. I wonder how bad an incandescent bulb would be. I still want to check the voltage with my scope too.

author: macboy
author_rank: Super Contributor
timestamp: December 28, 2024, 01:19:48 pm
content: Smells like badly designed PFC in that new PC power supply.

author: MathWizard
author_rank: Super Contributor
timestamp: January 11, 2025, 11:15:29 pm
content: Well I finally looked at it with a scope, plugged in on the same breaker, w/ 50x differential probes, and I can clearly see the line wiggle when the main PSU turns on. The pk-pk is always growing and shrinking a bit, as my SDS2204x+ updates on 10ms/div. Taking a few screen shots, and scrolling through them, it's easy to see it change.The STBY power doesn't do it.I tried to measure some stuff, but IDK how useful it was, since the average line voltage moves around over the minutes too. Maybe late in the night, I can get to good tests back-to-back.But really, what can be done, without taking apart the brand new PSU ?? Would it be defective ?? Overall these are way too complicated for me to know what to change, but can the input filters be changed any ? Or can I plug it in to an external filter of any type that would help this ??So far I can't say I've seen the flicker any better/worse, when the PSU was under a heavy load.Here's about as detailed a tear-down that exists. The fan is control is pretty annoying, I'm already tempted to void the warranty just to alter it's control.https://www.techpowerup.com/review/super-flower-sf-1200f-14mp/4.html

author: edpalmer42
author_rank: Super Contributor
timestamp: January 12, 2025, 01:33:38 am
content: You could try adding a plug-in filter to the powerline. You don't want a surge suppressor, you want a filter. Some power bars have them built-in. Sometimes a single unit combines both a filter and a surge suppressor.Ideally, add the filter to the power connection for the computer only. If that doesn't help, try using it to filter the power to the light.

author: wraper
author_rank: Unknown
timestamp: January 12, 2025, 01:44:30 am
content: I suspect PC internals changed with PSU as well. Most likely what you're seeing is just power consumption fluctuation or PFC amplifying mains voltage fluctuation by increasing current draw when mains voltage dips. That LED bulb is shit. Get a decent non dimmable bulb and forget about it. You're seeking for a problem when there aren't.

author: MathWizard
author_rank: Super Contributor
timestamp: January 12, 2025, 03:23:14 am
content: Ok I'll try without the powerbar, and I'll unplug my stereo on the same breaker, that's about it besides if I plug in a PSU, DMM or scope.I want to check the other outlet circuits, if they are all this bad, it will be bad for most all of my test equipment, and I might consider another PSU. It is oversized for my needs, I hope that's not making the powerline noise worse.I built this computer myself, and on the day I changed only the PSU, I immediately noticed the light flicker. And I've tried some Noma brand LED's, and a CFL? one, and they all flicker.

author: wraper
author_rank: Unknown
timestamp: January 12, 2025, 03:40:12 am
content: Dunno about those but decent bulbs should have LED current feedback loop and large enough bulk capacitor to not flicker on mains voltage fluctuation.

author: jonpaul
author_rank: Super Contributor
timestamp: January 12, 2025, 03:05:17 pm
content: check PSU min load rqmt.Dnt expect much from China junk PSUj

author: wraper
author_rank: Unknown
timestamp: January 12, 2025, 03:15:33 pm
content: Quote from: jonpaul on January 12, 2025, 03:05:17 pmSuper flower is about as good as you can possibly buy and is high end OEM of PSUs sold by other better known brands. Calling it Chinese junk means you don't know anything about PC PSUs.

author: MathWizard
author_rank: Super Contributor
timestamp: January 17, 2025, 11:17:55 am
content: Here's the PFC controller IC, the main controller is some custom unlisted IC. Unless I missed it, I don't see a low power burst mode. It is running at a fixed 67kHz.But I see Vcontrol and a Vcontrol capacitor, and they talk about a control bandwidth, of under 20Hz, to achieve a power factor of 1. Well to my eyes anyways, I'd say the flickering is a few times/second.I didn't unplug my stereo or anything else. Probing the mains w/ a Diff. Probe and looking at the FFT, there wasn't much difference between the PSU ON/OFF. But it doesn't take much to make make an LED bulb another brightness. Past say 2kHz, there was hardly any difference on the line, and looks pretty clean to me, but I'm not used to looking at the mains. I'm guessing this noise makes it into most of my test gear tho.I haven't found a datasheet for the PSU, on the SuperFlower website, they say " No Load Operation". In heavy games, using on average 300W or more, it still flickers.

author: Circlotron
author_rank: Super Contributor
timestamp: January 17, 2025, 11:44:32 am
content: It would be interesting if you could put a current clamp around one of the AC power wires and look at the moment to moment current on a scope.

author: MathWizard
author_rank: Super Contributor
timestamp: January 17, 2025, 03:26:54 pm
content: I don't have one, that's on my short list. I'm not sure what setting are best for looking at mains. For FFT, I read to use Flattop, and Peak-and-hold. IDK if using HighFreReject triggering helps or not.I know ERES cuts down the memory depth, I didn't use it in those FFT's. And I couldn't get my 2204X+ lower than 9Hz/div, I'll try it again, and run some benchmark on my system to use some more power.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 17, 2025, 03:40:34 pm
content: sine you have a more powerful psu, the led load and other connected stuff maybe is not enough and the pfc runs so so according the the load it manageshave you tried with a heavier load on the psu how it react, if you see the pfc acting faster ...sure as other wrote, inrush current etc ... or maybe add ac line filteringor in the end this brand is meh ? have you other available psu's to test, or maybe isolate your led stuff to another psu ?

author: MathWizard
author_rank: Super Contributor
timestamp: January 17, 2025, 07:26:47 pm
content: Ok so it does seem like a minimum load issue. With actual benchmarks running, in CineBench w/ the CPU pulling 220W, the flickering goes away, but between passes, the CPU powers down enough, that I can clearly see the flicker return, then go away again as it powers back up.And in Prime95 pulling 245W CPU, the light bulbs, sharing the wall socket, seem ok. There's not very much on this breaker, just the Computer, the lights and stereo, and a DMM/scope/PSU once in a while.I'm already running enough fans and drives, so the only thing I could add to increase the load, would be lighting. I could use some more light, but not all the time.But I don't want all extra noise on the mains, so I'll have to see about returning this oversized PSUand I must update the date on my scope.

author: Coordonnée_chromatique
author_rank: Frequent Contributor
timestamp: January 17, 2025, 08:25:00 pm
content: Quote from: wraper on January 12, 2025, 03:15:33 pmQuality and expertise are two different things, there are perhaps some old brands that are able to design PSU with a silent operation on the entire power range ?

author: wraper
author_rank: Unknown
timestamp: January 17, 2025, 09:32:19 pm
content: Quote from: Coordonnée_chromatique on January 17, 2025, 08:25:00 pmSo far I only see evidence of shitty LED bulbs. Power consumption spikes during idle-ish PC operation are normal. FFT measurements presented above are worthless because bulb flickering is caused by voltage fluctuation, not harmonics.

author: wraper
author_rank: Unknown
timestamp: January 17, 2025, 09:41:21 pm
content: Also I really doubt it's Leadex ‎platinum SF-1200F14MP as that is a decade old model. OP is talking about returning it, which implies it's brand new. Current one is LeadexSEplatinum ‎SF-1200F14MPV2.

author: MathWizard
author_rank: Super Contributor
timestamp: January 18, 2025, 03:26:23 pm
content: The release date of this PSU on Newegg where I bought it was March2024. I'll email the company, see if they will tell me any minimum load figure.https://www.newegg.ca/super-flower-leadex-platinum-se-sf-1200f14mp-v2-1200w/p/1HU-024C-00037?item=1HU-024C-00037&utm_source=transactional&utm_medium=email&cm_mmc=TEMC-Shipping-Notice-CAN-_-101930&utm_campaign=TEMC-Shipping-Notice-CAN-_-101930So it's the SF-1200F14MP V2My eyes seeing the bulbs, say it's a minimum load problem, as I could see it get bad when the load drops down between Cinebench passes.I just put in a 60 or 100W incandescent, I can still notice it, but it's not as annoying as the LED's, so maybe is it the SMPS in these bulbs, really don't like the PSU.

author: wraper
author_rank: Unknown
timestamp: January 18, 2025, 05:28:51 pm
content: Quote from: MathWizard on January 18, 2025, 03:26:23 pmSo power consumption decreases, mains voltage rises, bulbs change brightness = somewhat high wiring resistance (exaggerated by 120V mains voltage) and shitty bulbs.

author: MathWizard
author_rank: Super Contributor
timestamp: January 25, 2025, 12:38:19 am
content: Well the NOMA brand certainly doesn't attach the the LED mains wires very good, they are just laid in place. The hot wire is stiff solid-core and laid on a metal dome basically, and the neutral wire is stranded, and basically just brushed up against the bulb screw. And that wire looks to have some carbon buildup.I've taken apart 3 broken NOMA LED bulbs over the years, 2 last week. The 1st one had the 1st inductor fall apart/crumble.The 2 last week, on 1, the core/base of the 2nd inductor broke apart, but it was on the un-connected GND pin. But the non-GND side of the inductor, lifted the solder pad right off.The winding pins were ok otherwise, but desoldering it made one pin fall out , but at least the wire hasn't broke yet. And the 1st inductor in the circuit, also had a pin fall out.Then the 3rd one, I'm guessing has a bad cap, or bad controller, nothing else seems wrong, or maybe a bad mains connection since they don't solder the wires. When plugged in, this one flickers ON/OFF in some reset loop.I can't find anything on the controller IC.Here's the schematic, w/ a resistive load and no feedback, so far I can only get a few Watts from it, not up near 13W yet.Both electrolytics are 130C degrees rated tho, that's the 1st time I remember seeing caps over 105C. Yet their inductors have heat issues, or whatever, and fall apart.