Does a high quality SMPS 'power brick' (Wall wart) exist? - Page 1
Forum section: electronics / general

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 07, 2022, 07:02:53 pm
content: Having had a number of SMPS problems recently, tracked down to the usual component failures, is it actually possible to buy decent quality SMPS units that won't either blow up, wear out and/or pollute the street with RF?

author: thm_w
author_rank: Super Contributor
timestamp: February 07, 2022, 11:20:01 pm
content: If you can get ahold of name brand laptop adapters, usually those will be good (Asus, sony, apple, dell, etc.), from thrift store or electronics recycler.I have some quality 12V 4A units (WEIHAI), but doubt its worth shipping to UK just for that.If you buy generic no-name from amazon you are almost guaranteed to get garbage.What specific voltage and power are we talking about?

author: Whales
author_rank: Super Contributor
timestamp: February 08, 2022, 12:48:22 am
content: +1 to piggybacking the computer market. Genuine laptop chargers and off-the-shelf ATX power suppliers from good brands all tend to be very good.I've opened up some off-brand laptop chargers and cheap ATX power supplies before, it's typical to see all of the input filtering (X caps & common mode chokes) missing. Recently I discovered some 12V wall power supplies I bought from a local supplier emitted so much conducted noise that my raspi zeros (after a 12->5V buck) would "work" but couldn't initialise their wifi chipsets. My scope showed something like intermittent 1Vp-p pulses coming from the wall wart

author: Cerebus
author_rank: Super Contributor
timestamp: February 08, 2022, 05:51:05 am
content: Meanwell produce inexpensive reliable supplies. They have quite an extensive range of wall warts and external power brick style supplies. I've not used any, but I've had good experiences with their OEM type enclosed and open frame supplies. Beware that there are quite a lot of Meanwell imitators/counterfeiters out there. As one of the few Chinese companies to have earned themselves a decent reputation they get ripped off a lot, so only buy through trusted channels.

author: John B
author_rank: Frequent Contributor
timestamp: February 08, 2022, 06:20:36 am
content: I purchase meanwell stuff from element14 (especially when they have voucher specials). They have the best prices that I can find. Other resellers aimed at "prosumer" markets tend to have quite a markup.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 08, 2022, 07:47:23 am
content: I hate to rain on the parade, but this was a Mean Well product. Made in Taiwan.And from RS Components too. Which is PRECISELY why I bought them - an OK make, an OK supplier and NOT made in china.Having had it open I wouldn't say it was designed particularly well - the 450V cap was laid flat on the PCB: covering the opto-isolator and right across the Mains/ELV separation space, and so spewed its contents from the vent directly onto ELV components. Resistors and diodes right underneath the cap too. Very cool ventilated spot.The actual circuit looks reasonable and with decent fuse/surge/XY and CM choke on the input. It's an IEC input socket so could have even used the earth for some Y class rejection, but hasn't.EDIT: the SMPS was specified at 12V DC 1.5A. The actual consumer device was max 500mA. Plugged in 24x7, but zero quiescent draw and cycle time about 1 minute per week on.In any event, as soon as chinese components go in, you take your chances on whether the make faked the specs that particular day.Good idea re seeking out (good) laptop ones - I have on occasion bought Apple USB adapters to use for 5V supplies where you can get away without any 'handshaking' problems.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 08, 2022, 10:12:36 am
content: Just plugged in the brand new and unused one.It's already up to 53degC outer plastic case with no load, and this appears to be coming from the switching transistor.I note also that the PCB has tracks to allow Y class caps to be added back to a vacant hole where the earth pin of the IEC could be wired.

author: all_repair
author_rank: Frequent Contributor
timestamp: February 08, 2022, 10:47:00 am
content: Get the SMPS rated for medical use if you want best afforable quality.Most of the problems are created by dropshippers selling factory rejects and grade E bricks online. Their value-added is their English language abilities, and for most profits they sourced for the cheapest.I have been running a cheap no-name Chinese 12V open frame SMPS 247 for many years. It is powering my NAS and network gears.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 08, 2022, 10:49:14 am
content: You beat me to it - just looking through the 'medical' grade ones right this minute.I doubt that they are any better, but there's a very tiny possibility if any are truthfully tested/labelled.

author: Karel
author_rank: Super Contributor
timestamp: February 08, 2022, 10:50:30 am
content: Quote from: 6SN7WGTB on February 07, 2022, 07:02:53 pmYes, it's actually possible. Buy a medical approved powersupply from Mouser, Digikey, etc.For example:https://www.cincon.com/Medical_Power.htmlhttps://www.digikey.com/en/products/filter/ac-dc-desktop-wall-adapters/130In Filters -> Applications -> select: MedicalBut you'll pay more and most people hate that...

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 08, 2022, 11:59:06 am
content: I would more than happily pay more for something that (a) might work for more than 6 months and (b) won't potentially kill me and/or my family!However, I suspect most of the members here feel similarly, but we're the minority globally.Consumer organisations should force legislation to display CoO on every item we buy. That would start to focus the mind on the source of the world's problems.

author: ve7xen
author_rank: Super Contributor
timestamp: February 08, 2022, 07:09:34 pm
content: Quote from: 6SN7WGTB on February 08, 2022, 11:59:06 amI would agree, but more because shipping things back and forth around the world isn't environmentally sustainable, so I would like to see more distributed production.CoO says essentially nothing about quality. Consumers demand low prices, and suppliers everywhere will engineer products to satisfy them. I will agree it is hard to identify quality products these days, as neither price nor CoO is much of an indicator, as witnessed by your Taiwan-made product that is apparently junk, but simply labelling CoO isn't a good proxy. Practically everything is assembled in China, from the dangerously low cost products to the most lauded-for-quality brands, it has nothing to do with nationality and everything to do with 'sort by price'.Laptop PSUs are generally higher than 12V. For quality 12V supplies, look for monitor, network equipment or thin client power supplies from OEM vendors like Dell, HP, Juniper, and Cisco. Often manufactured by Delta or LiteOn.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 08, 2022, 07:16:18 pm
content: Quote from: 6SN7WGTB on February 07, 2022, 07:02:53 pmStuff from mainstream distributors is usually Ok - in the UK : CPC, Rapid, Farnell,RS or Stontronics for volume orders.Also run them well below their specified power for best lifetime

author: electr_peter
author_rank: Unknown
timestamp: February 08, 2022, 08:34:08 pm
content: Plug packs from IKEA are one of the best options to get good consumer level power adapters. Much better and more consistent than regular hardware/electronics store. See detailed test/teardown herelygte-info, Ikea Koppla USB 5V 2A

author: wraper
author_rank: Unknown
timestamp: February 08, 2022, 08:38:25 pm
content: Quote from: 6SN7WGTB on February 08, 2022, 07:47:23 amThose primary caps almost never vent, especially with spewing electrolyte. Unless overvolted, which very likely was the case.

author: thm_w
author_rank: Super Contributor
timestamp: February 08, 2022, 11:31:30 pm
content: Quote from: 6SN7WGTB on February 08, 2022, 10:12:36 amThis makes no sense, the good units I have draw <0.1W in standby, so do not heat up at all, which is a requirement from most countries energy standards.What is the part number?

author: John B
author_rank: Frequent Contributor
timestamp: February 09, 2022, 12:41:16 am
content: Something sounds amiss. I have a whole bunch of the Meanwell GST series adapters in various voltages and currents and have had no failures, also they run cool under load, so they must be far more efficient than the no-name brand cheap adapters they replaced.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 09, 2022, 07:34:42 am
content: Here you go.Quick and dirty standby check shows 2W/5VA. Current is 28mA at 238V.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 09, 2022, 07:41:10 am
content: (a) The top was bulged, and there appeared to be a small crack along one of the vent lines when examined closely. Not 'exploded' but vented' so my word 'spewed' was perhaps ill advised.(b) There was some staining in line with the cap top on two LV components(c) There's residue everywhere, concentrated in the vicinity of the cap top direction.Just reporting what I am finding. We all know it "shouldn't" but it "has".

author: SteveyG
author_rank: Unknown
timestamp: February 09, 2022, 08:47:14 am
content: XP Power is pretty much the highest quality from all the testing I've had to do at work. They're also mainly UK based which is nice. Stontronics, Friwo and MeanWell would be 2nd in line from my experience.MeanWell have very differing product lines however, so whilst they make some brilliant and reliable medical power supplies, they also make some really cheap ones that will fail.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 09, 2022, 09:46:15 am
content: Opened up the unused spare.Admittedly with the heatsink (a very small thin strip of steel) removed in order to open it, the transistor on the input side runs very hot with no load.Let it cool off for 5 mins then putting 1A on as load, rapidly heated up again so no different aside the output device starts to heat up as well (as you'd expect).The cap in the unused one tests fine for value, ESR and leakage, albeit only tested to 160V DC.The cap in the dud is completely open circuit.I did have a Doh! moment - there are two small plastic plugs in the base which can be extracted with something sharp to reveal two fixing screws... No need for the hacksaw.

author: thm_w
author_rank: Super Contributor
timestamp: February 09, 2022, 10:55:19 pm
content: ES18Obsolete, 1 year warranty, no mention of no load power:https://www.mouser.ca/datasheet/2/260/es18a-spec-1179813.pdfGST182 year warranty, <0.075W no load powerhttps://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/GST18A/GST18A-spec.pdfLooks like GS18 might be better. Not cheap though, $25.ES18 from ~2010, not really that old, no excuse why its garbage.

author: Electro Fan
author_rank: Super Contributor
timestamp: February 10, 2022, 07:20:49 am
content: I’m using a Mean Well GST18A12-P1J in very close proximity to a weak signal RF system where maintaining a low noise environment is important. I can’t (easily) prove how well the Mean Well is enhancing or inhibiting performance of the overall system but the system seems to be working on par.

author: wraper
author_rank: Unknown
timestamp: February 10, 2022, 09:19:29 am
content: Mean Well makes PSU of a very different quality for different price ranges. Cheapest stuff comes with cheap components and not very good specs. More expensive has all Japanese caps, and high efficiency.

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 10, 2022, 09:20:14 am
content: Quote from: wraper on February 10, 2022, 09:19:29 amDo you know which ones?

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 10, 2022, 09:22:36 am
content: Quote from: Electro Fan on February 10, 2022, 07:20:49 amJust bought a 'medical grade' GEM18 12V and will test it out. Also will run the RF wand over it.

author: wraper
author_rank: Unknown
timestamp: February 10, 2022, 09:29:55 am
content: Quote from: 6SN7WGTB on February 10, 2022, 09:20:14 amThe most obvious sign is warranty period in the datasheet. Really good stuff will have 5+ years warranty. Although for something like this 3 years seems to be the maximum.https://www.meanwell.com/productPdf.aspx?i=1045

author: wraper
author_rank: Unknown
timestamp: February 10, 2022, 09:32:00 am
content: Quote from: thm_w on February 09, 2022, 10:55:19 pmActually it has 3 year warranty.

author: Electro Fan
author_rank: Super Contributor
timestamp: February 10, 2022, 05:39:16 pm
content: Quote from: 6SN7WGTB on February 10, 2022, 09:22:36 amMedical grade might be good/better. Let us know what you learn.https://www.onlinecomponents.com/upload/leaderboard/7ce8b89d-4e4c-4798-a639-eee2b73262b9.pdfhttps://www.meanwellusa.com/upload/pdf/GST18A/GST18A-spec.pdf

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 11, 2022, 05:50:52 pm
content: The briefest of tests, and qualitative at that.I have used a Paul Carlson design 'Super Probe' which as many of you will know is a sensitive wide band detector. So, my measure is just 'noise'. But with audible feedback, and an LED showing a trigger level, it's at least a comparator for level and content.Plugged in the Mean Well GEM18I12 and a no-name 12V with same 1.5A rating.Off load:(a) The 'noise' of the Mean Well right up to the case is quite low and subjectively of moderate content. It drops away about 5cm from the case(b) The 'noise' radiated along the cable of the Mean Well is also low and ditto. Need to be within a cm of so to pick it up properly(c) The noise of the Won Hung Lo is excruciatingly loud near the case, contains very high pitched content and drops away at about 10cm(d) Similarly the cable of the WHL broadcast a very high level of a similar noise which is highly detectable again about 10cm away.Under Load:(a) The WHL quietens down significantly losing most of the HF 'noise' but is still easily detectable 7cm away from the whole cable (plus the load I plugged into it became a good radiator)(b) The Mean Well is pretty quiet and only sensibly detectable about 1 or 2cm away.All terribly subjective I know, but basically an order of magnitude difference in level and content.