Mean Well power supply - mini teardown - Page 1
Forum section: electronics / projects

author: Miti
author_rank: Super Contributor
timestamp: February 09, 2020, 01:42:16 am
content: Yesterday I bought a Mean Well RQ-85D power supply to repair an IFR2025 RF signal generator that was missing it's PS. I'll have to say that I was enough impressed with the quality and attention to details that I decided to post some pictures. For the price, I was expecting a typical Chinese type product with lots of cut corners and crap, but I was greeted by a clean, properly manufactured product with quality parts. I will not comment on the electrical design, I don't have the schematic and I don't have enough design experience to do so, even though I repaired a fair amount of SMPSs in my life.So far, every time I needed a power supply at work, I ordered Delta, TDK Lambda, XP Power, etc., but they are way more expensive than Mean Well or are open frame, forced air. etc. This time I decided to go with the cheapest one and I can tell you, Mean Well has a place in my AVL.Before I post the pictures, here are some pros and cons:Pros* Low cost.* Relatively small, compact.* Good quality capacitors. You can look all you want for those CrapXon caps, you won't find them.* Ferrite beads everywhere, on the rectifier diodes, on the caps, even on the bridge.* Big Rubycon input filter caps.* Healthy amount of RTV in lots of places.* Thin FR4 (like) insulator between the PCB and the case.* Proper fuse, common mode choke.* Lots of routings in the high voltage areas.* Big, chunky chokes at the output. Is that a saturable core reactor or just a choke?Cons* There are no pems in the mounting holes, the thread is directly in soft aluminum, very easy to strip. Ask me how I know...Edit: * No PFC.Enough talk...

author: Miti
author_rank: Super Contributor
timestamp: February 09, 2020, 01:45:51 am
content: More pictures...

author: Miti
author_rank: Super Contributor
timestamp: February 09, 2020, 01:47:21 am
content: Two more pictures.

author: tooki
author_rank: Super Contributor
timestamp: February 09, 2020, 10:13:22 pm
content: Very nice pix!But FYI, this is no surprise: Mean Well has an excellent reputation. They are by no means considered a cheapie Chinese brand. They have a full range of PSUs, from budget to medical grade. I’ve used them for a number of projects over the years.

author: Miti
author_rank: Super Contributor
timestamp: February 09, 2020, 11:04:13 pm
content: Quote from: tooki on February 09, 2020, 10:13:22 pmThe popular wisdom says that you get what you pay for and it is true most of the time. Based on this principle, we don’t buy the cheapest at work. Mean Well may be the exception that proves the rule. 😁

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 09, 2020, 11:26:35 pm
content: It confirms my idea of the brand but it's always good to have a periodic benchmark to see whether they cheaped out in the meanwhile. Thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 10, 2020, 05:27:35 am
content: What controller? UC3842, or something else?Looks very typical for their work. The ferrite beads are a dog's breakfast kind of thing, perhaps they actually needed all of them, or perhaps it's not worth optimizing further even given the quantities they're producing.Which, let me see. Probably... fractional millions of units, for a given part number? Say another $10k in the lab to optimize EMI, so has to save say $0.05/unit x 200k qty to be worthwhile? They're probably getting those ferrite beads for pennies each (or fractions even?), and they're probably getting Chinese labor cheap enough to thread them onto the component leads for less than $0.05/ea, so, y'know, that's really not a terrible decision.They do have enough of 'em, that replacing a bunch with one or two small (DM) chokes might be attractive. But maybe not quite enough so.Shrug.Anyway -- the design I would guess is 1-switch forward, hence the single primary side switch, and output choke; secondaries would be multi tapped, and rectifiers are per output. Possibly the TO-247 is for the 5V 6A output? The multi-winding choke filters all of them together (saves on cores, and helps a bit with cross-regulation innit?), plus either a charge pump (i.e. half wave voltage doubler) or a spare winding on the choke that generates -V, perhaps -15 to -18V, for a 7912, for the -12V output.PCB is glass composite (FR-2 is it?), one layer, standard fare for cheap PSUs, and not so cheap as paper phenolic. Probably some EMI issues could be solved with better (2-sided) layout, but I would imagine they thought of that, and went with the cheaper option. (Perhaps threading ferrite beads really is just that cheap to do!)Caps are brand name, so unless they've been counterfeited, they should be quite good, and MW has a positive reputation in the west so I would hope they are keeping track of things to maintain that.I haven't been using anything long enough, that uses a MW power supply that I know of, to have even an anecdotal opinion on their reliability (which is perhaps a good thing, not having had a failure to speak of -- but it's also a small sample size, so not all that meaningful). As a designer, I certainly consider them acceptable.Tim

author: Miti
author_rank: Super Contributor
timestamp: February 10, 2020, 12:01:24 pm
content: Quote from: T3sl4co1l on February 10, 2020, 05:27:35 amON NCP1203P60.

author: tooki
author_rank: Super Contributor
timestamp: February 10, 2020, 02:00:18 pm
content: Quote from: Miti on February 09, 2020, 11:04:13 pmWell, mean well is FAR from the cheapest! All you’ve proven is that the lowest costlegitimate brandisn’t junk!Believe me, you can get far cheaper, far junkier no-name power supplies. You just don’t necessarily get them on digi-key and other vendors that refuse to sell garbage!

author: TimNJ
author_rank: Super Contributor
timestamp: February 10, 2020, 02:50:48 pm
content: I think Mean Well is perfectly fine as long as you know what you're buying. In my opinion, their datasheets can be a bit "tricky", but just read all the notes/fine print. Reliability wise, they have a ton of buying power, hence they can afford to use name brand stuff and still be low cost.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 10, 2020, 04:04:41 pm
content: Worth noting, from the couple units I've tested in lab -- the EMI tends to be marginal to high, so you may want to add an input line filter, or output CMC (followed by a 'Y' cap between mains earth and circuit ground). For the wired modules, that's easy enough, just use a filtered power entry module and wire them together. For PC mount modules, provide footprints for CMCs and 'Y' caps.They do carry approvals, but I suspect they're done with some kind of minimal fixture that doesn't get a full picture of EMI conducted from the output leads (e.g. maybe they just go to clip leads to a load resistor on the bench, not another LISN).That was specifically a board mount module we were testing, also we tried some by XP Power and I forget who else. The "medical grade" ones performed the best, and also have lower ground leakage ('Y' caps in the 100s pF range). The very compact modules (we started out with one of those tiny square bricks by XP Power) are unfiltered by the way, so depend wholly on your filtering to pass. Provide optional extra filtering for those.Tim

author: TimNJ
author_rank: Super Contributor
timestamp: February 10, 2020, 07:41:00 pm
content: True. Often the EMI conditions are something ridiculous like "passes when power supply mounted on 600mm x 600mm steel plate", for some tiny 2" x 4" power supply.

author: nctnico
author_rank: Super Contributor
timestamp: February 10, 2020, 08:07:47 pm
content: Quote from: tooki on February 10, 2020, 02:00:18 pmYou can also get much more expensive power supplies which are worse compared to Meanwell. Omron comes to mind.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 11, 2020, 01:03:58 am
content: Quote from: T3sl4co1l on February 10, 2020, 04:04:41 pmAt one place I worked, Mean Well was indeed one of the nosiest PSUs out there. I even removed the Y caps from one to make it the "extra noisy" one. (The purpose was to test that the DUT will operate properly in the presence of such noise.)

author: Miti
author_rank: Super Contributor
timestamp: February 11, 2020, 02:57:34 am
content: Quote from: tooki on February 10, 2020, 02:00:18 pmYes, I meant the cheapest from Digikey, Mouser, etc. For my projects I buy only from these two.

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 11, 2020, 03:16:27 am
content: I've generally been impressed with the build qualoty of the Mean Well suppliesI tend to look at them first before other brands on Digikey/Mouser if I can't find a surplus TDK Lambda PSU in Akihabara etc.

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2023, 09:53:24 am
content: Necro-post warning.

author: dkonigs
author_rank: Regular Contributor
timestamp: June 21, 2023, 03:16:13 pm
content: Quote from: T3sl4co1l on February 10, 2020, 04:04:41 pmYeah, noticed this too. Using an IRM-10-12 in a project, just built the first prototype with it, and decided to do some testing. Even in total isolation from my real load, the conducted emissions are terrible. I have no idea how it got all of the approvals it claims to have, and claims to get them without external components. Okay, it might pass with zero load, but with even the smallest amount of load it jumps all over the limit lines and then has this weird repeating pattern on the spectrum analyzer at higher frequencies.Eventually I'm going to need to decide whether its better to solve the issue with input filters, or by simply using a different brand. (Used a CUI PSK-6B-S12 in a previous prototype, which tests a lot cleaner but has much worse availability. Also been considering a Cincon CFM06S120-E, but haven't tested it yet.) I guess its eventually going to come down to a question of whether adding filtering to the Mean Well costs more/less than an alternative that doesn't need the filtering.

author: Stray Electron
author_rank: Super Contributor
timestamp: June 21, 2023, 11:16:46 pm
content: First, Meanwell is located in Taiwan, not China. I'm surprised that no caught that.Second, IMO the Taiwanese make some very good electronics. I suspect that it's a big reason that China wants to take them over.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 22, 2023, 01:03:47 am
content: "China" as opposed to "West China", if you will. RoC. Or in the sense that they speak Chinese there, which includes both of course.Tim

author: mawyatt
author_rank: Super Contributor
timestamp: June 22, 2023, 03:19:44 am
content: Quote from: Stray Electron on June 21, 2023, 11:16:46 pmDidn't know that, thanks!!Agree Taiwan is very good at electronics, and TSMC, well they are in another league along with Samsung when it comes to leading edge semiconductor fabrication. These folks have left everyone else far behind regarding pushing the feature size technology envelop, and continue to do so.Sure anyone would benefit from gathering up TSMC, just hope this doesn't happen as for sure this will lead to another conflict at the cost of many lives.Best,

author: zrq
author_rank: Frequent Contributor
timestamp: June 22, 2023, 09:03:09 pm
content: Quote from: Stray Electron on June 21, 2023, 11:16:46 pmAlso GWInstek and ITECH are Taiwan based instead of political China.It very unfortunate that Taiwan and mainland China have so much commonality in culture, language and lifestyle, but having so strained relation due to political reasons. I really enjoy hanging out with a Taiwanese colleague of me, he speaks a more "standard" mandarin than me.

author: Stray Electron
author_rank: Super Contributor
timestamp: June 23, 2023, 01:09:40 am
content: Quote from: T3sl4co1l on June 22, 2023, 01:03:47 amLet's see; the Canadians, the South Africans, some of the Irish and the Scots, the Australians and the New Zealanders, the Americans and of course the Brits; all speak English. But I would hardly call them East or West Brits or South Brits or Upside Down Brits.The point is that Taiwan and the PRC (or whatever you prefer to call it)aretwo different countries regardless of weather they speak the same language. And to the point of this thread, the quality of their electronics is vastly different.

author: faiz4h61
author_rank: Newbie
timestamp: January 08, 2025, 05:45:36 am
content: Hi. I want to buy some of the component in this model. Transformer and Inductor. how can I get the value for this item ya? dont know how to measure that