EEVblog #1152 - 240V-120V=Magic Smoke - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: December 05, 2018, 08:58:22 pm
content: Dave's 120V Weller WE1010 released the magic smoke when plugged into 240V...PEBKAC for sure, but a potentially dangerous design flaw too?

author: tautech
author_rank: Super Contributor
timestamp: December 05, 2018, 09:06:12 pm
content: Will this fit ?https://www.jaycar.com.au/9v-24v-60va-5a-multi-tapped-dual-output-type-2167-transformer/p/MM2014

author: glarsson
author_rank: Frequent Contributor
timestamp: December 05, 2018, 09:24:13 pm
content: No video of the main event. This is unacceptable.Dave should have cameras on 365/7/24.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 05, 2018, 09:33:57 pm
content: The higher voltage will drive the transformer core into saturation. This will increase the current on the primary side quite a lot. So burning the primary is about normal. I am kind if surprised that the secondary fuse blew.Normally I would have expected a thermal fuse at the primary. So the transformer would be still broken, but less smoke and fire danger.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: December 05, 2018, 09:38:36 pm
content: IIANM, as soon as the core saturates the flux won't increase anymore and the secondary voltage won't increase anymore either, but, the primary current would increase like crazy because in saturation it (the primary) becomes a short circuit. That, plus some design headroom in VINmax in the PCB circuit is what saved it, I would say.And if you've got 50Hz there, it aggravates the situattion because that transformer is a 60Hz one.

author: tchicago
author_rank: Regular Contributor
timestamp: December 05, 2018, 09:51:18 pm
content: I think you should now make an educational video about the magnetic core saturation. And then, at the end, explain how this led to the isolation meltdown in this transformer.You have all necessary lab equipment to demonstrate this effect. Without a smoke of course, but showing that the AC current goes through the roof when the core saturates.

author: Neilm
author_rank: Super Contributor
timestamp: December 05, 2018, 10:10:33 pm
content: 240 x low resistance = lots of smoky fun

author: vzoole
author_rank: Regular Contributor
timestamp: December 05, 2018, 10:32:07 pm
content: Quote from: EEVblogThis Weller is UL approved and UL61010-1 is the related standard. But anyway all country use standard with similar content just different title.USA - UL61010-1Europe - EN61010-1Hungary - MSZ61010-1Worldwide/Europe - IEC61010-1It says...Quote from: UL61010-1I can't see any exception to leave fuse in main circuit...But I think the circuit breaker of house is enough.Like in the NOTE1 "Overcurrent protection devices supplied with the equipment are intended..." so it suppose the overcurrent protection doesn't has to be built in the device.

author: floobydust
author_rank: Super Contributor
timestamp: December 05, 2018, 10:39:41 pm
content: I'm not sure why European designs have no fuse on transformer primaries.I see primary fusing as a regulatory requirement in North American products, OR a (primary) thermal fuse at the least. Sometimes the primary wire ends up being the fuse which melts.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 05, 2018, 10:48:54 pm
content: The complete absence of any kind of protection on the primary side is mind-boggling.They assumed that only the circuit powered by the secondary side could become faulty.I guess they may have gotten away with it by stating both on the underside label and in the user's manual that it's a 120V device only, so it was probably never tested in lab with any higher mains voltage.This could seem sort of acceptable, but it would assume that the transformer itself can't fail if powered correctly, or the associated wiring to the mains plug, which is more wishful thinking than realistic. Also, as there is no protection whatsoever on the primary side (no fuse, no MOV, no nothing), any overvoltage on the mains line could potentially fry the transformer.Short of very cheap/fake equipment, I think this is the first time I get to see something like this. All my soldering stations have fuses on the primary side, from cheap Atten stuff to the relatively high-end ERSA ones.

author: eV1Te
author_rank: Regular Contributor
timestamp: December 05, 2018, 11:04:28 pm
content: Classic core saturation as many have said already, and they might be able to blame the user if they apply double the voltage to to the product.But a similar effect could be caused by a short in a single turn of the primary or the secondary, this could easily happen during manufacturing if the enamel is scratched or someone jams a tool into the winding during installation. So no fuse on the primary is a serious fire risk in transformers.Here is an example of what happens if a single turn is shorted (it does not matter that the remaining part of the secondary is not there):

author: floobydust
author_rank: Super Contributor
timestamp: December 05, 2018, 11:12:09 pm
content: Quote from: vzoole on December 05, 2018, 10:32:07 pmThis thing hasfake approvals???That explains the fire hazard. It's just got CE... for limited sections tooWhenever I see a bodge (barnacle) consisting of a hand-soldered fuse in series with a polyfuse, you know they had problems. That is plain silly, only dumbasses do that.All I see isIEC 60335-2-45clause 17 is about transformer protection but I don't have that doc.Product brochure/Datasheet says nothing about approvals but some distimarketing says says "UL and CE listed."UL Certifications DirectoryI could not find Weller or Cooper Tools, they might not use UL?The transformer does not output 2X Vprimary due to saturation, which is why the primary burned up.WE 1010NAHmm they have $20 rebate offer for it.

author: tszaboo
author_rank: Super Contributor
timestamp: December 05, 2018, 11:18:14 pm
content: For example Metcal uses SMPS for their RF heating system, so it has universal input.Yes, I like Metcal.Quote from: floobydust on December 05, 2018, 11:12:09 pmhttps://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=KQLR.E18708&ccnshorttitle=Heaters,+Industrial+and+Laboratory&objid=1074016910&cfgid=1073741824&version=versionless&parent_id=1073989224&sequence=1

author: floobydust
author_rank: Super Contributor
timestamp: December 05, 2018, 11:22:01 pm
content: +1 Thanks, I can sleep now knowing it has UL approvals to probably UL 60335-2-45. The WE1010NA is North American version.So is it the safety standard that let the house burn down? No primary fuse is a no-no.edit: looked into the soldering iron safety standard IEC 60335-2-45It doesn't cover it:17 Overload protection of transformers and associated circuits"Appliances incorporating circuits supplied from a transformer shall be constructed so that in the event of short circuits which are likely to occur in normal use, excessive temperatures do not occur in the transformer or in the circuits associated with the transformer.NOTE Examples are the short-circuiting of bare or inadequately insulated conductors of accessible circuits operating at safety extra-low voltage.Compliance is checked by applying the most unfavourable short circuit or overload which is likely to occur in normal use, the appliance being supplied with 1,06 times or 0,94 times rated voltage, whichever is the more unfavourable".

author: MrMobodies
author_rank: Super Contributor
timestamp: December 06, 2018, 12:27:23 am
content: Some of the old Wellers did come with removable fuses.https://www.parts-express.com/pedocs/manuals/372-140-weller-wtcpt-manual-41680.pdfhttps://www.electronicspoint.com/threads/weller-wtcpn-problems.26547/Quotehttp://vk4ghz.com/weller-wtcpt-soldering-iron-switch-mod/I can't see it clearly but is that a fuse cover on the bottom right?It looks like they are cutting corners of safety.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 06, 2018, 12:58:53 am
content: Take the transformer outside and connect 240V to it (with a heater or something in series to prevent the fuse blowing), then see if it actually catches fire.

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: December 06, 2018, 03:02:55 am
content: Brings back memories of me smoking power transformers when I was a kid , totally shorting out the secondly until the magic smoke escaped outThe cores would do the "60 hertz hum of death!"

author: mariush
author_rank: Super Contributor
timestamp: December 06, 2018, 03:25:28 am
content: On a product that costs this much seems a bit silly not to include some protection for this sort of thing.Just off the top of my had, could have something as simple as a diode for half wave rectification, a high voltage ldo like LR8K4-G to get 12v/24v or something that would power a comparator or something which measures input voltage and turns on a relay/triac/whatever if mains voltage is less than 140v.1-3$ worth of parts when your margin is over 100$...

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: December 06, 2018, 03:53:40 am
content: Quote from: EEVblog on December 05, 2018, 08:58:22 pmI have a lot of mixed voltage gear, quite a bit of it from the US (120V Weller stations) with 240V Weller stations on the same bench. I keep the US IEC mains lead always connected to the US to prevent this kind of mistake.

author: Muttley Snickers
author_rank: Unknown
timestamp: December 06, 2018, 04:46:40 am
content: You can't really blame Weller for this mistake or any other manufacturer for that matter where products are imported from elsewhere and then used in countries that they were not intended or designed for. To help minimise the chance of this happening again Weller could easily add a warning label near the IEC connection, perhaps users could also be more diligent and add their own big bold warning sticker to the front of odd equipment as a permanent reminder and to alert other users who may not be aware of the products origin.

author: berniwa
author_rank: Newbie
timestamp: December 06, 2018, 09:23:04 am
content: Hey guys,I checked the datasheet for the Weller WE1010 and it is supposed to conform to EN 60335-1: 2012-10.I don't have the exact standard at the office, but the old version from 2007 instead of 2012,but the changes should only be minor.I only have it in German, so I'll translate the basic bits:19 Improper Operation19.1 ...Electronic circuits need to be designed and operated in a way, that a single failure of the device doesn't make it unsafe in terms of electric shock, fire hazard, machanical hazard or dangerous malfunction.Note 2: Fuses, temperature cutoffs, overcurrent-limiter or equivalent may be used to provide this safety. The safety mechanisms of building installation do not provide the required safety.So in my opinion this seems illegal, at least according to EU regulation.It may as well be, that it is allowed in the US and they have a built in fuse for EU units.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 06, 2018, 10:13:05 am
content: I still have a lot of 120V only gear in the lab and a big transformer to supply it all.To prevent this from happening, each instrument got a big yellow sticker on top "120V only!"It is a surprise to see a "Designed and Engineered in Germany" product with no protectionon the primary. I am producing test stands myself and they have to have a primary protection.

author: Ian.M
author_rank: Super Contributor
timestamp: December 06, 2018, 10:27:00 am
content: IMHO its a flaw in the IEC60320 connector standard that it doesn't include ridge/groove keying to discriminate between 120V and 240V/universal voltage applications. The standard does discriminate between C14 cold condition inlets and C16 hot condition inlets so a C15 cold condition cord cant mate with a C16 hot condition inlet, but a C17 hot condition cord can mate with either, so if the initial standards committee had been a bit less US centric, they might have done the sensible thing. However 50 years later, that's what we are stuck with.Weller not fusing the primary is unforgivable, as even in the target market 240V circuits are common and if miswired there is a risk of 240V appearing on an ordinary 120V 20A duplex outlet. I wouldn't expect a replaceable fuse, but they were penny pinching in the extreme not to include a thermal fuse in the primary.

author: PartialDischarge
author_rank: Super Contributor
timestamp: December 06, 2018, 01:09:57 pm
content: That goes against all safety standards, violates 61010, and common sense standards too. Even a Yihua 858 has input fuses, as anything mains connected be it smps or linear transformer must have, and this is not about single or double isolation for operator safety, but for fire safety.

author: jonovid
author_rank: Super Contributor
timestamp: December 06, 2018, 01:16:34 pm
content: if this was meuse angle grinder to cut the weld & split the transformer E pack then remove the burnt primary winding off the bobbin. add some new fiberglass tape if needed. then just rewind the primary with new wire todoublethe same length for 240volt then add 20% on top this that for 250-260volt. for AUthen re pack the transformer E-pack with some bolts to hold it together.use the same AWG wire size as the old. IMO! add a primary fuse.

author: DocBen
author_rank: Regular Contributor
timestamp: December 06, 2018, 01:28:01 pm
content: Had to check my ERSA Analog 60.Primary fuse.The Weller is probably "designed by intern (TM)"

author: tszaboo
author_rank: Super Contributor
timestamp: December 06, 2018, 02:03:34 pm
content: Quote from: DocBen on December 06, 2018, 01:28:01 pmIt is the cost cutting. It's a 100 dollar soldering station, where the iron itself is 55 dollar. The same company sells sidecutters that cost more. I dont really understand why they marketed as the grey series (professional) instead of red series (consumer) but after seeing the review and seeing this video... I really dont understand. I mean, maybe they make 10-20 EUR on each sale, selling an iron which is terrible, further eroding the name, and whoever buys this, doesnt going to buy tips by the dozen to make up for it with the profit.

author: EEVblog
author_rank: Unknown
timestamp: December 06, 2018, 02:14:44 pm
content: Quote from: Muttley Snickers on December 06, 2018, 04:46:40 amExcept for when the primary fails due a manufacturing fault or other failure and then melts down and catches on fire with the regular 120V input.Not having at least an internal thermal fuse in the primary is just bad design practice, possibly against standards, and increases company legal liability. i.e. they didn't use industry standard "best practice" and very deliberately cost cut at the expense of basic safety.

author: EEVblog
author_rank: Unknown
timestamp: December 06, 2018, 02:18:11 pm
content: Quote from: floobydust on December 05, 2018, 11:12:09 pmIf it says ULlistedthen it must actually be registered with UL. You could get it ETL tested for example to the same UL standard, but you cannot say it's UL listed.It has the UL listed mark on the bottom.Have you checked "Apex Tool Group"?

author: Muttley Snickers
author_rank: Unknown
timestamp: December 06, 2018, 02:24:17 pm
content: I agree that the primary lacked any form of even basic protection but as that aspect was already mentioned numerous times both here and in the comments I didn't bother repeating it, they should still add a rear label to stop idiots just adding a bigger fuse should it keep blowing.

author: tszaboo
author_rank: Super Contributor
timestamp: December 06, 2018, 02:26:00 pm
content: Quote from: EEVblog on December 06, 2018, 02:18:11 pmThis is the UL listing:https://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=KQLR.E18708&ccnshorttitle=Heaters,+Industrial+and+Laboratory&objid=1074016910&cfgid=1073741824&version=versionless&parent_id=1073989224&sequence=1

author: DocBen
author_rank: Regular Contributor
timestamp: December 06, 2018, 02:39:55 pm
content: I think it is actually supposed to be a model for educational institutions. No worries they're just children.Cant wait for marketing to rebrand it as their "outdoor activity model":Outdoor because you're house will have burned down.Activities:Running (from the fire)Swimming (to cool your burns)

author: SeanB
author_rank: Super Contributor
timestamp: December 06, 2018, 03:49:21 pm
content: Take the Hakko fake and use the transformer in it for a replacement. Probably the same size or at least will fit, and will most likely also have a primary side thermal fuse in it, and then you can transplant the secondary side PTC with a new solder in back up fuse. then mark it as a 240V unit and keep it around. Probably cheaper than a new Weller transformer.However I remember a very expensive mistake made, where there were identical power outlets next to each other, and the only differentiation between them was the labelling. One was a 16A 400VAC 50Hz 3 phase plus neutral and PE, and right next to it on the wall, identical blue IEC socket outlet, was a slightly different supply, 16A 115VAC 400Hz 3 phase plus PE aircraft ground supply, provided from a rotary converter in the complex. Brand new apprentice, first day there, and told to " take this trailing lead to the wall ( vague gesture to wall with 2 sockets next to each other) and plug it in", and brand new apprentice does so, and the in charge turns on the aircraft, turns up the ground air supply to max cooling, gets out the cockpit and they go to lunch, as it takes around 40 minutes for the avionics to power up and complete self test and self alignment from cold.They come back from lunch, walk in the door and are greeted by the sight of the aircraft drooling the magic smoke from every opening, vent and cowling. much talk and analysis, and the conclusion was that " Box, electric centre, protection relay" that was supposed to not connect power unless it was within 100-135VAC 360-445Hz with all 3 phases present, did not work correctly when presented on the sense inputs with 380VAC 50Hz, and did not disconnect the power relay.

author: Dave
author_rank: Super Contributor
timestamp: December 06, 2018, 05:06:00 pm
content: Quote from: johnlsenchak on December 06, 2018, 03:02:55 amThat would actually be the 120 Hz hum.Magnetostriction only cares about the absolute magnetic field density, which has two peaks in one sine period, therefore double the frequency.

author: floobydust
author_rank: Super Contributor
timestamp: December 06, 2018, 05:07:18 pm
content: I've asked Weller why the station does not have a fuse on the primary and if I can purchase a jar of magic smokeWill update if I hear from them.A complaint can also be filed with UL/CSA, if S/N and model # are submitted.I've gone through this before and it's quite disappointing due to politics.Assuming a mistake has been made- in product design, or assessment or applying the incorrect safety standard, or an omission in that particular standard:-A manufacturer would have to issue a product recall.-The regulatory Agency contract waives all liability or responsibility on their part. I find they (i.e. UL) does not admit anything as nobody wants egg on their face, tarnishing their reputation. They may offer a free re-assessment of the product.-Contacting the IEC standards committee- the bureaucracy is impossible to navigate and they are no different in that a stupid/missing clause takes years to get introduced.It might be a manufacturing error in Mexico. There is no place to solder a fuse at the xfmer primary terminals. The (secondary) fuse+PTC combo is proof an idiot was involved. I know a fuse is required on the primary, it's even common sense.

author: chris_leyson
author_rank: Super Contributor
timestamp: December 06, 2018, 08:04:30 pm
content: That's a seriously bad design, it isn't a manufacturing error because you can see that the connectors on the wiring looms fit exactly where they should. It's a serious design error where cost down has taken priority over safety. Any reputable company would do open and short tests on wiring looms, connectors and even individual components on PCBs. I have to do that with my designs, not literally shorting each component but making sure that worst case combinations of opens or shorts result in a safe failure that isn't going to cause a fire or electocute the end user. Looks like Weller don't take much care or don't show any due diligence when it comes to safety.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: December 06, 2018, 10:06:09 pm
content: Quote from: Muttley Snickers on December 06, 2018, 02:24:17 pmIt is interesting that when I checked my 120V & 240V Weller stations I have all appear to be fused on the primary. Would have expected therefore that this would have been just BAU across their line.

author: thm_w
author_rank: Super Contributor
timestamp: December 06, 2018, 10:10:45 pm
content: Quote from: chris_leyson on December 06, 2018, 08:04:30 pmGood point, there is a very small chance the 4A fuse is on the primary in the original design and whoever drew the manufacturing drawings really screwed up. But seems unlikely.What is the point of having a 7A SRF and and 4A fuse in seriesI can't see this making any sense unless they expected the heat from the transformer to couple into the SRF somehow?https://www.digikey.ca/product-detail/en/bourns-inc/MF-R700/MF-R700-ND/259979

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 06, 2018, 10:38:46 pm
content: Fromhttps://weller-tools.com/we1010na/Quote

author: Deodand2014
author_rank: Regular Contributor
timestamp: December 07, 2018, 01:08:03 am
content: For what it's worth, a repair/upgrade video might be interesting. I have an old AC adaptor that has 240V input on the primary to output 24V @ 50a on the secondary I'm willing to sacrifice.

author: EEVblog
author_rank: Unknown
timestamp: December 07, 2018, 01:32:40 am
content: FYI, I've contacted a director at Apex Tools, will see if I get any response.

author: Brumby
author_rank: Unknown
timestamp: December 07, 2018, 02:52:20 am
content: Dave - have you checked your PO Box mail in the last day or so...?

author: floobydust
author_rank: Super Contributor
timestamp: December 07, 2018, 02:56:49 am
content: To be fair, Hakko FX hasMET Labsapprovals file E212152 for UL 499 Electric Heating Appliances, CSA C22.2 No. 122 Hand-Held Electrically Heated Tools.These are different safety standards than what Weller has EN 60335-1, -2-45.Hakko B3722 PC Board with Fusefor FX-888D. Seems like a good idea. Will it fit in the Weller?edit: added pic

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 07, 2018, 07:24:12 am
content: My unsorted thoughts on this:Any fuse you add primary would need a certain voltage and current rating that is oriented on the devices operating voltage. So you´d have to install a 240V fuse in the 120V device... just in case?!Taking it ad absurdum what if someone connects 750V? Nothing against good quality fuses, but they would need mystery rating for inrush current and voltage - to be safe against this mistake.The 120V transformer has half the amount of primary windings a 240V model would have at the same output VA, but at a bigger cross sectional area (thicker gage). The inrush current is therefore a lot higher than nominal, and especially higher when it goes in saturation.A fuse itself would not protect a damaged transformer from overheating, insulation faults can overheat and burn at nominal current (the short being of unspecified resistance - worst case scenario). At the same time fuses could blow because an intact transformer was switched on at extreme outside conditions... like cold temperature, high grid voltage. So one would need a very slow fuse, but when that opens, the insulation might already be partially damaged and the device is a ticking time bomb.I reckon there is no perfect protection in this case, might be the best alternative to have the transformer short out and melt all of its insulation, as long as there is no particulary flammable material around it. The winding insulation´s physical properties (melting point, conductivity) has the biggest impact of all protective measures. Unfortunately it also means that the insulation should not degrade much or loose these properties when aging. Fuses do not have this problem, but they don´t help much with less than ideal shorts.edit: I´ve got to admit if it would happen to my gear i would equally ask for more protection components. The outcome however shows a few things:- Lab did not burn down- Device is defective and will cause house installation breaker to open- Transformer is fully shorted, not partiallyMost people would replace a primary side fuse with a higher current rating, which would not make the device safer at all, but the existence of a fuse might make the transformers insulation cheaper by manufacturers design decision. Then the part could really burn down the house. A huge part of this safety relies on the house installation being up to code. That´s a questionable way of handling the devices safety, but in the end an inspector needs to check what caused the issue and would it have been caused with a different device on the same outlet. If the installation is not up to code you´ve got a problem.Imho the real mistake is here: 120V device in 240V Australia, featuring an IEC-C13 connector! Leaving that connector away would reestablish safety by having the proper, incompatible plug.

author: BravoV
author_rank: Super Contributor
timestamp: December 07, 2018, 07:32:34 am
content: Just for comparison at old genuine Hakko 936 controllers, one is rated for 230V but for 50Hz, and another for 220V but 60Hz.As Dave said ... "they did pay attention to the detail", just watch the fuse spec at the white warning label.

author: capt bullshot
author_rank: Super Contributor
timestamp: December 07, 2018, 08:47:51 am
content: Such stuff has to be tested to achieve CE / UL whatever.I guess it has been tested for secondary shorts and overload, that's the way the secondary fuse and polyswitch creeped in. From my experience with testing according to standards (whatever standard applies) today, everyone does test exactly what the standard and auditor requires, but nothing more. So, in case the standard didn't require testing a 120V unit at 240V mains, no one would have tested that.Here, where I'm working, one can see strange things happen.For example, someone designs a flyback converter for a 24V to 12V (plus several auxiliary voltages) conversion, it's a flyback because isolation is required and it's always been a flyback for that kind of application.Now, some testing happens. Someone else discovers, the transformer runs hot if one of the auxiliary outputs is shorted or overloaded. The flyback isn't designed to go into hiccup mode then (for unknown reason, or maybe just ignorance), so the transformer runs too hot. Now an protection circuit gets added to each auxiliary output that shuts down the converter in case of overload or short. Test passed then, everything is fine, converter board costs more than planned - no one cares now. Only the orignal designer was pushed to reduce cost, not the other ones that added the protection circuit.This converter circuit get reused once. Someone discovered the controller doesn't limit the output power in case of the main output is overloaded. By chance, the original designer was asked and added a clever workaround at minimal cost. Test passed, everything is fine.Not this converter, including all the protection circuitry plus the original designers clever workaround gets reused again, by some new designer who isn't familiar with the original designers intents. The circuit just gets copied, for some reason a new transformer is designed (smaller than the orginal one), and one auxiliary supply is removed. So the removal of this auxiliary output also removed the snubber circuit (one more clever idea of the original designer was to use the primary snubber as an auxiliary output) - a new snubber circuit is added to make it work again. This circuit gets tested and someone else discovers the primary controller doesn't shut down it the main output is overloaded. The original designers clever workaround is still there but doesn't work here because of the new transformer or whatever. The one who is testing doesn't know about the clever workaround anyway, so he adds another (complex looking) protection circuitry that isn't working on the first try, so a respin is needed. Finally test passed, everything is fine.Result: a very compicated looking schematic of an rather simply flyback supply. Best part still to follow: At some point the requirement for isolation was dropped, input and output GND were bonded together and the whole thing could have been done with a way more simpler buck regulator.So, I'm really not surprised at all by the missing primary fuse and the bullshit polyfuse / fuse combination on the secondary with this transformer.

author: EEVblog
author_rank: Unknown
timestamp: December 07, 2018, 01:43:47 pm
content: Quote from: SparkyFX on December 07, 2018, 07:24:12 amOf course it would, that's why it's standard practice in almost every other bit of mains power gear in existence.A correctly sized and typed fuse would be guaranteed to break with 240V on a 120V primary, or a gross failure in the 120V primary under normal supply.Use a slow-blow if you are worried about inrush current.

author: thm_w
author_rank: Super Contributor
timestamp: December 07, 2018, 11:15:52 pm
content: Quote from: SparkyFX on December 07, 2018, 07:24:12 am120V fuses are generally capable of handling 240V as-is, no need to overrate. Its not like it would *operate* at 240V, its blowing in 5s or less.https://www.digikey.ca/product-detail/en/bel-fuse-inc/3AG-15-R/507-1629-ND/1009968

author: Kilrah
author_rank: Unknown
timestamp: December 10, 2018, 12:10:34 pm
content: Quote from: EEVblog on December 06, 2018, 02:14:44 pmYou did not completely tear down/unwind the transformer, I would expect there to be one in the center. It likely just needed a few more seconds to trip since the whole mass has to heat up (one can see only the outer layer really got hot, the center windings don't have damaged insulation yet).The thermal fuse is there more as a long term overload protection, not really appropruiate for this case although it's likely it would have tripped before things got melty enough to affect outside stuff (smoke is impressive, but it takes a lot more heat before there is a real risk of setting external stuff on fire).This really needs a fuse on the input. Pretty crazy, never seen a direct input in a long time even on the cheapest Chinese crap I have.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 10, 2018, 07:00:58 pm
content: Hope this is not seen as pedantic, i just think it is a good conversation.Quote from: EEVblog on December 07, 2018, 01:43:47 pmI think of such systems more as a question of overheating protection than the current itself as feedback... comparable to a motor protection that needs to match the installed motors size to trip even below the nominal electrical current for the given wire gauge when running in overload-condition... therefore potentially overheating the winding insulation. Temperature sensors/fuses in the windings are of course another, more telling option as a protection.Long story short: The operational range of an electrical (melting) fuse just does not 100% overlap the operational range of a transformer, simply because the mass of the fuse and the mass of the coil are drastically different and any designed protection can only be as good as the specification of the error it should avert. I reckon no one foresaw to run it at 240... too bad it has the IEC connector in the back that allows it. Operating devices outside their spec is a killer to the question of which approvals the device has.Floobydust pointed out the differences which approvals were applied, so if i would need to guess, thissoldering stationwas probably classified as aheating device, where the risk of overheating prevails the electrical dangers (again, current is a weak indicator for heat produced). Maybe such a classification is a sneaky way around the need of a fuse.The requirements of intra-device protection and those of house installation protection also vary heavily by country (e.g. over here for house installation the fuse dimensioning is dependent on the surrounding material or air the cables are covered in by a correction factor).But i never understood the legal binding of these approvals, although i think i get what is tested or approved there.There are quite some open questions, like if the detachable supply cable is part of the device (an internal fuse will not protect of a damaged cable).Quote from: thm_w on December 07, 2018, 11:15:52 pmThe design intent of a fuse is more or less shifting the big part of the voltage drop from a circuit to the fuse, therefore dissipating most of the power there, therefore "blowing" at a rated speed. Some loads however expose different dangers and fail different than just by overcurrent. At best a fuse would protect the internal wiring excluding the transformer... but there is no metal case, although there is ground.A 120V fuse will presumably have no problem of shutting down the nominal 230/240V by air gap. But when talking about transients or arc flashing, when connected to such a grid i´d expect them to have higher requirements = higher price, even though there is no CAT rating on the device. Should the fuse arc over, it wouldn´t open the circuit. Maybe i see this too narrow, as if considered only in high energy networks.

author: thm_w
author_rank: Super Contributor
timestamp: December 10, 2018, 08:09:11 pm
content: Quote from: Kilrah on December 10, 2018, 12:10:34 pmSeems unlikely. Generally its on the outer windings and the transformer would have some indication of one being inside (bump in the tape, or a label).https://www.eevblog.com/forum/beginners/is-a-thermal-fuse-a-current-fuse-as-well/https://eessential.blogspot.com/2014/11/product-failure.html

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 10, 2018, 08:31:35 pm
content: Quote from: SparkyFX on December 10, 2018, 07:00:58 pmA dropped neutral in 120v countries is not an unforseen event.What did seem strange to me is that UL hasn't got a lot registered under this category, and what is are mostly soldering guns and firesticks. There is a Snap-On transformer based station. But maybe they just don't do a lot of soldering station work.I don't remember seeing a soldering gun of the transformer type having a fuse, but perhaps they do?

author: G7PSK
author_rank: Super Contributor
timestamp: December 11, 2018, 04:04:16 pm
content: Either it is poor design or that is a knockoff Weller, just checked both my cheapie soldering stations one circuit specialist and a Bakon from banggood and they both have fuses soldered to boards,so the Pace unit has a fuse drawer built into the IEC socket which not only has the fuse but also holds a spare but of course thats a lot more money.

author: glarsson
author_rank: Frequent Contributor
timestamp: December 11, 2018, 05:06:38 pm
content: It can't be a knockoff. A knockoff would certainly have a fuse.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: December 12, 2018, 01:44:32 pm
content: Quote from: SparkyFX on December 07, 2018, 07:24:12 amFor the typical small glass tube slow blow fuse form factor, isn't a 240V/1A fuse the exact same thing as a120V/2A120V/1A fuse? It's an I2R device, V does not matter much (within reason).Edit: typo.

author: Kilrah
author_rank: Unknown
timestamp: December 12, 2018, 01:48:05 pm
content: Quote from: GeorgeOfTheJungle on December 12, 2018, 01:44:32 pmReread what you wrote, slowly...

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 12, 2018, 02:44:07 pm
content: Quote from: GeorgeOfTheJungle on December 12, 2018, 01:44:32 pmI was of course writing this regarding the isolation voltage after it blew - with respect to arcs/transients and general safety aspects as Dave points out in his multimeter teardowns when it comes to CAT ratings. Even though this soldering station is not CAT rated, transient overvoltage does exist, probably damage the transformer directly (a fuse wont help with that), but any additional part needs to be able to handle it?The nominal voltage rating on the fuse is given for isolation, not in relation to it´s current carrying characteristics. Obviously that´s not an "operating voltage" which it is supposed to permanently drop, it is a fuse - a safety switch and that is it´s isolation voltage. Come on!The discussion is getting very abstract and theoretical. I´d say there is no right or wrong way to prepare a device for this, the scenario was not a use case in the first place, the risks stay with the party that imported it to the jurisdiction. Questions around device protection usually run down to what statistically is likely to the general safety - not the most extreme outliers.Of course a dropped neutral that connected to the other phase can happen, but that would also mean you try to solder in the dark and the beer gets warm.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 12, 2018, 08:00:12 pm
content: Quote from: SparkyFX on December 12, 2018, 02:44:07 pmYou've got your soldering iron on, plugged into a split outlet. You plug your new reflow oven to the other socket and turn it on. There's a bad connection on the outlet's neutral that gets worse when you dump 1500W through it and it opens.Know what you speak of.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 18, 2018, 06:45:42 am
content: Split outlets and the code for them are a new-to-me concept, as i am on a different continent. So excuse the dumb question: isn´t a double neutral feed required for those, as the gauge needs to match the cross sectional area for the live wire anyway? I don´t know if cable with two gauges in one sheathing would be usual.. hence two live/two neutral would make sense.But i think i get what you address: a floating neutral on a per outlet basis... a lower impedance load would be in series with the device at double (180° split) the operating voltage, shifting the voltage drop according to their impedance (guess 0.8A/12.5A nominal=224,6V/15,4V), while the current for both is drawn through the soldering stations feed line/transformer/switch/fuse*. A fuse could help with that, but it heavily depends which device and which kind of device is switched on first.OTOH: If the other, unkown device had a higher impedance, the soldering station would have undervoltage, lower current.House installation and devices are usually handled separate, as the device manufacturer can only cover his part, not the rest of the installation and vice versa.

author: paschulke2
author_rank: Contributor
timestamp: December 18, 2018, 05:51:09 pm
content: Quote from: nsd_c on December 18, 2018, 05:42:50 pmThey were – until 2016. In 2016 manufacturing was moved from Besigheim in Germany to Mexico and 130 workers were laid off in Besigheim.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 18, 2018, 06:53:39 pm
content: According to the WE1010 manual (see here:https://media-weller.de/weller/data/OI/OI/WE1010_OperatingInstruction.pdf), they claim compliance with EN 60335-1:2012. I took a look at it.("Safety of Household and Similar Appliances, Part 1: General Requirements")Interestingly, as Dave suggested, the EN 60335-1 doesn't *require* the use of any fuse or even any specific protection measures at the primary side. They may be used as a means of being compliant, but are not strictly required.The fault conditions that are tested are ALL simulated while the device is powered at the *rated voltage*, except two. There is basically one test in which the input voltage is lowered until the device stops functioning, then it's raised again to the rated voltage - and the device should be back to an operating state (probably to simulate power cuts). The other is a surge test, but as the surge pulses are relatively short, the transformer probably takes the abuse gracefully, and the protections at the secondary side are sufficient...To get away with not doing anything more, they probably selected a transformer that is already tested compliant to some UL standard, and documented the device's fabrication process. And there you go.This is still dubious engineering practise, but the device is most likely compliant to the required standards indeed...

author: Richy_T
author_rank: Newbie
timestamp: December 19, 2018, 09:44:04 pm
content: Quote from: MrMobodies on December 06, 2018, 12:27:23 amFrom other pictures I've seen, that's a grounding point for an anti-static strap.I think Dave should accept Weller's offer of the 240V version so we could see if it has a fuse. Though it's kind-of surprising that there's no one who can tell us for sure on here already.

author: floobydust
author_rank: Super Contributor
timestamp: December 19, 2018, 09:52:34 pm
content: In the pic I see three leads and think a thermal fuse is in the 240VAC transformer:https://www.eevblog.com/forum/blog/eevblog-1160-weller-responds/msg2051086/#msg2051086

author: EEVblog
author_rank: Unknown
timestamp: December 19, 2018, 10:55:39 pm
content: Quote from: Richy_T on December 19, 2018, 09:44:04 pmWeller had their opportunity to tell us that, I or anyone else shouldn't have to do that for them.

author: udok
author_rank: Regular Contributor
timestamp: December 20, 2018, 01:27:40 pm
content: Just for information:My Weller WMD-3 240 Volt soldering station has a primary Fuse,which is resetable.It is a rather expensive Schurter T11-211 1.5A.

author: Clear as mud
author_rank: Regular Contributor
timestamp: December 30, 2018, 02:55:59 pm
content: Quote from: SparkyFX on December 18, 2018, 06:45:42 amAs you said, the two live wires would be 180 degrees out of phase, so when both are in use, the current in the neutral would subtract, not add. A single neutral is all that's required, and it is the same gauge wire as the two live wires.The electrical code in the US has become more strict in this in recent years. They call this a "multi-wire branch circuit," and you used to be able to legally run it off two separate breakers in the panel, of course making sure that they were on opposite legs of the incoming service. But now those breakers are required to have at least a handle tie, so one can not be shut off without also shutting off the other.Personally, I still like the idea of using multi-wire branch circuits, for conservation of resources and operation of the circuits with lower voltage drop. Particularly in a commercial setting with wires running through conduit, if you follow the code requirements on de-rating ampacity when you have multiple conductors in the same conduit, you can really save a lot of materials if you use multi-wire branch circuits. For instance, on a 3-phase system, 3 circuits can share one neutral and only count as 3 current-carrying conductors (because the neutral current cancels out, at least when driving linear loads that don't introduce harmonics). But if you ran each of the three circuits with its own neutral, you have to count it as 6 current-carrying conductors, and then you have to increase the size of conductor because you have to de-rate the amps rating when you have so many conductors in one conduit.NEC Table 310.15(B)(3)(a). Then you have to increase the conduit size because the conductors are bigger.The Code has been evolving towards prohibition of multi-wire branch circuits with shared neutrals. Many electricians and electrical system designers now like running each circuit with its own neutral for greater reliability (not having to shut off multiple circuits to work on one) and less danger in case of an open neutral.

author: Clear as mud
author_rank: Regular Contributor
timestamp: December 30, 2018, 03:35:03 pm
content: Quote from: SeanB on December 06, 2018, 03:49:21 pmI found where you told this same story before, but with more detail:https://www.reddit.com/r/talesfromtechsupport/comments/5cgzcy/one_of_the_worst_nights_of_my_life/d9wxgdc

author: janekivi
author_rank: Frequent Contributor
timestamp: January 20, 2019, 11:08:04 am
content: I got very expensive station when working in telephone company, it is 25 year old...actually it never was at work - I was using it only at home : ) Mains fuse is locatedat front panel there, never looked inside or opening the fuse.https://commons.wikimedia.org/wiki/File:Loetstation_Weller_WTCP-S.jpgI had similar blue alpha Rosin Core solder wire reel... sweet smell.But my hi-tech new soldering station doesn't have any fuse, even protective sleevesare loose on mains connection. "Hakko'd" together from UPS transformer, clone frontpanel and HAKD 907 handle.I don't know who to blame...: )))

author: floobydust
author_rank: Super Contributor
timestamp: January 20, 2019, 07:17:55 pm
content: No ground or fuse, on/off switch? Think of all the money you saved.Maybe Weller is hiring? They are looking for people like yourself

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 23, 2019, 02:11:29 am
content: Quote from: floobydust on January 20, 2019, 07:17:55 pm

author: lpc32
author_rank: Frequent Contributor
timestamp: March 15, 2019, 05:13:27 am
content: Quote from: SparkyFX on December 07, 2018, 07:24:12 amHakko's fixed cable-and-plug didn't help in my case.And still, I'd much prefer a C14 inlet.At least the fuse therehelps.

author: EEVblog
author_rank: Unknown
timestamp: June 03, 2019, 01:04:36 am
content: More Weller fun!

author: floobydust
author_rank: Super Contributor
timestamp: June 03, 2019, 03:22:04 am
content: Weller could be smarter and add a terminal point - but a lousy twist-on Marrette connector? More manual labour in Mexico and no final test for the product. Hmmm.Soldering guns generate a many kV spike at the tip on trigger switch off. Don't use them on electronics! KILLERWhere's a video of the arc on the switch to prove I'm not crazy.

author: Dundarave
author_rank: Regular Contributor
timestamp: June 03, 2019, 04:06:03 am
content: Quote from: floobydust on June 03, 2019, 03:22:04 amHow is that possible? The secondary that forms the tip is like a single loop buss bar, a dead short. When I was a young kid, the Weller gun was all I had, but granted I was only soldering wire in tube circuits and transistors, nothing static sensitive. In all those years, I don’t think I ever saw a spark off that tip.

author: Ian.M
author_rank: Super Contributor
timestamp: June 03, 2019, 04:32:01 am
content: Capacitive coupling of the back-EMF spike from breaking the primary circuit, to the secondary is how. However its pretty easy to mitigate. Simply connect the inner end of the primary to neutral, not to the switch, to minimise the coupling, and put a snubber across the switch.

author: floobydust
author_rank: Super Contributor
timestamp: June 03, 2019, 04:55:53 am
content: I was a kid, figured it out while soldering a neon lamp in a some old gear.It flashed every time I toggled the triggerThe solenoid-style transformer has high leakage inductance as well, to make it worse.I told my mechanic buddy to never use a soldering gun on cars and trucks, it could damage the electronics. It's pretty much the only place you need so much heat to solder.

author: Dundarave
author_rank: Regular Contributor
timestamp: June 03, 2019, 05:15:44 am
content: Quote from: floobydust on June 03, 2019, 04:55:53 amThanks. I can certainly understand how the electromagnetic pulse would flash a nearby neon, and I’m sure I’ve had the same thing happen to me back in the day, but I didn’t understand how a spark could actually be generated at the tip from back EMF, especially when my experience indicated otherwise.But between the large e-mag pulse, and Ian.M’s explanation, I can see how today’s sensitive chips wouldn’t likely stand a chance.Not that I was ever likely to use a Weller gun again for my electronics work, lol.

author: mcovington
author_rank: Regular Contributor
timestamp: September 21, 2019, 11:00:09 pm
content: I discovered that my old Weller EC2000 soldering station likewise had no fuse upstream from the transformer primary, so I opened it up to add one... and found that it had been built with live and neutral interchanged. The published diagram is correct and what I actually found obviously has them backward. Neutral was connected to the switch.So now I have even less confidence in Weller than I did after watching the videos!(Disclaimer: It is conceivable the swap was done by someone repairing it later. In any case, I have replaced the power cord.)

author: floobydust
author_rank: Super Contributor
timestamp: September 22, 2019, 03:49:01 am
content: your blogadding primary fuse,nice picsI don't see a primary fuse in theWeller EC2000 manual,only the secondary 2A 24VAC circuit breaker EC212 which is useless. It could only deal with a shorted cable/connector to the handle - but does that even happen? It's there only to meet antique UL (soldering iron) standard UL499.I'd guess the EC2000 uses the Tyco power transformer that may be UL/CSA Class II rated.

author: noJunk
author_rank: Contributor
timestamp: December 29, 2019, 08:13:10 pm
content: That's nothing.Around year 1995-2000 most industrial\home equipment had the 120/240 switch nearby the POWER ON\OFF.The 120/240 switch on 600Watt ++ would also trigger the sound and remove a certain quantity of O2 in the adjacent room.

author: docsalr
author_rank: Contributor
timestamp: September 23, 2024, 12:40:22 am
content: I did the light switch mod and the primary side fuse to my WE1010. I placed a 1A fuse according to my calculations but the Hakko FX-888D with almost similar specs has a 2A fuse....any thoughts?Also for the illuminated switch, I had to switch the live and neural wires from the IEC plug and had to add a neutral to the switch as well.