EEVblog #1160 - Weller Responds

[drussell]

a) Weller should know better than to sell an unfused device that could easily end up in a different country in 2018 (eg. ebay has been around for over 20 years).

Wait, you're saying that all electronics, appliances, etc. should be built to some mythical worldwide standard that covers all situations, all regulations in all jurisdictions?

[drussell]

PS: Does anybody know why these things even use old iron transformers instead of switch-mode supplies?

It's just a simple 12V heating element (or 24V, or whatever).

I think you answered your own question. 

Personally, I would much prefer the simple, reliable transformer in such a device rather than some silly switching supply.

[Mr. Scram]

PS: Does anybody know why these things even use old iron transformers instead of switch-mode supplies?

It's just a simple 12V heating element (or 24V, or whatever).

Dave mentioned it in the original video. Something to do with switchers not liking the high current on and off switching of a heating element.

[Fungus]

Wait, you're saying that all electronics, appliances, etc. should be built to some mythical worldwide standard that covers all situations, all regulations in all jurisdictions?

It only takes a $0.10 fuse... 

[Fungus]

Dave mentioned it in the original video. Something to do with switchers not liking the high current on and off switching of a heating element.

It's only 60W or so.

I find it hard to believe that manufacturing/shipping something with a heavy iron transformer costs less than a decent filter capacitor.

Edit: Maybe there's a video in this for Dave. 

[kosine]

There's no such thing as "proper "tool grade" PA6" - it's just marketing noise.

PA6 is softer and weaker than PA66, and melts at a much lower temperature. Typically 200-220C versus 250-280C. Glass-filled versions are better, but harder to mould and quite abrasive on the tooling.

Main reason for using PA6 instead of PA66 is the cost. It's easier mould and resin prices have increased enormously in the last couple of years due to supply issues. PA6 is the cheaper option, hence its prevalence. Both will burn nicely if they get hot enough. (Fire retardant plastics are very expensive and little used.)

[TheDane]

Dave mentioned it in the original video. Something to do with switchers not liking the high current on and off switching of a heating element.

It's only 60W or so.

I find it hard to believe that manufacturing/shipping something with a heavy iron transformer costs less than a decent filter capacitor.

Must be isolated from mains - expensive
More components to fail - warranty expenses
- every sub-cent apparently counts, I guess this is why a transformer is used.

Corp'ies - dead entities, no guilt or remorse. Will kill you at any chance. Go after management, just like the walking dead - only a head shot counts 

[drussell]

a) Weller should know better than to sell an unfused device that could easily end up in a different country in 2018 (eg. ebay has been around for over 20 years).

It only takes a $0.10 fuse... 

There are a hundred other ways for a typical device to fail that a simple fuse won't magically solve.  In most countries it is technically illegal to plug an incorrectly certified, out-of-region device into the mains.  Certainly if it does burn down your lab and your insurance company finds out you were using non-conforming electrical devices that you imported from some other jurisdiction, they're not going to pay your claim.

Don't get me wrong.  I'm surprised that this station doesn't have a primary fuse and would put one there if I were designing it, but the exaggerated claims about being death-trap level junk because it doesn't have a primary fuse are unfounded.

There are other, far sketchier devices out there.  Many of them are even legitimately tested and certified. 

[Fungus]

There are other, far sketchier devices out there.  Many of them are even legitimately tested and certified. 

Make a list. We can start on those after we finish with this one.

[mikeselectricstuff]

AFAIK safety standards only address fire, so it can probably put out as much smoke as it likes as long as it doesn't set something on fire, wouldn't surprise me if it didn't even mention toxic fumes.

[Fungus]

Don't get me wrong.  I'm surprised that this station doesn't have a primary fuse and would put one there if I were designing it, but the exaggerated claims about being death-trap level junk because it doesn't have a primary fuse are unfounded.

The full experiment hasn't been done yet.

We only have a single preliminary experiment that was terminated before conclusions could be drawn.

[Fungus]

Must be isolated from mains - expensive

You think switch mode supplies aren't isolated from mains?

- every sub-cent apparently counts, I guess this is why a transformer is used.

Cost of copper. Cost of iron cores. Cost of shipping them based on weight. It all adds up.

[Mr. Scram]

You think switch mode supplies aren't isolated from mains?

Cost of copper. Cost of iron cores. Cost of shipping them based on weight. It all adds up.

What makes you think the people working on cost optimisation in these huge firms haven't thought of that?

[Fungus]

You think switch mode supplies aren't isolated from mains?

Cost of copper. Cost of iron cores. Cost of shipping them based on weight. It all adds up.

What makes you think the people working on cost optimisation in these huge firms haven't thought of that?

Maybe their customers are old-fashioned and think that heavy iron power supply = quality/reliability.

(there's already a few examples of that in this thread)

[David Hess]

None of the hand held line voltage soldering tools have fuses and all are compliant to the Australian standards and have Australian electrical approval.

I know from personal experience that the 120 volt AC line voltage soldering pencils fail by having the heater go open when 240 volts AC is applied.  They are safe but expensively fragile.

[Zucca]

Louis Rossmann joined in the rant... check his YT channel. 

[eugenenine]

Your home stereo, wall warts, clock radio etc. consumer electronics all require a primary fuse of some sort in the power transformer.
Seeing that fuse on Hakko and other Weller products, Metcal etc. is common sense - but too bad the politics of a fuse are at play.

I have opened a lot of wall warts and small electronics (clock radio, etc) and very few have a fuse, it is not a requirement.

[Fungus]

I have opened a lot of wall warts and small electronics (clock radio, etc) and very few have a fuse, it is not a requirement.

a) Most (all?) wall warts use switch mode supplies and will accept a wide range of input voltages, even DC.

(do you own wall warts with huge iron transformers in them?)


b) The "requirement" will be that that devices fail safely, not that they must have fuses.

The reason fuses are being discussed here is that a fuse would be a cheap way to make Weller soldering stations fail safely. No other reason.

[eugenenine]

I have opened a lot of wall warts and small electronics (clock radio, etc) and very few have a fuse, it is not a requirement.

a) Most (all?) wall warts use switch mode supplies and will accept a wide range of input voltages, even DC.

(do you own wall warts with huge iron transformers in them?)


b) The "requirement" will be that that devices fail safely, not that they must have fuses.

The reason fuses are being discussed here is that a fuse would be a cheap way to make Weller soldering stations fail safely. No other reason.

a) Lots of non high current phone chargers are transformers.  The 200mA to charge a cordless screwdriver, the charger for the FRS radios you can but anywhere, chargers for cheap razor/trimmers, cordless phones, etc.  I've torn apart some simple radios, with and without clocks that had a simple transformer wired direct to the cord with no primary fuse.

even simple heating appliances like a toaster typically don't have a fuse in the main cord.

Yes, cell phones are switching but most other wall warts are not.

b) I was disputing someone saying fuses are a requirement, I haven't see anything that states fuses are a requirement and have seen plenty of evidence to show that fuses are not a requirement.

[capt bullshot]

SCNR 

[EEVblog]

Your home stereo, wall warts, clock radio etc. consumer electronics all require a primary fuse of some sort in the power transformer.

Not according to a direct quote from a product engineer at Weller, see my previous post for this.

[Ice-Tea]

your  not supposed to blow breakers. your not supposed to shut down an entire work bench and possibly room lights and smoke the joint up because of a 50 cent part. whoever designed this standard is a fucking moron

They were drafting an electrical safety standard. Not a convenience standard.

tripping a breaker is a safety issue.

Is it? I think you are still confusing "safety" with "convenience".

so is toxic smoke.

- What is your proof that the smoke is toxic?
- Even if it is, that's well beyond the scope of an electrical safety standard.

[EEVblog]

Louis Rossmann joined in the rant... check his YT channel. 

Haven't watched it, but I'm sure it's good 

[2N3055]

I have Weller WD1.
It has primary fuse and thermal fuse in transformer.
Problem is that 110V version specifies fuse of 1 A. 1A fuse will not blow if you connect 110V station into 240V in a time to save transformer.

Transformer might or might not overheat into short circuit. Some of them will just keep on smoldering. If primary wire is thin enough, it might even fail open.
Transformer wire coating is temperature resistant and flame retardant. If you heat it enough, it might char and become conductive, but not short, not immediately...
Current will rise slowly, until it finally either shorts, or breaks open.
If device catches fire it is usually case or something else made of non fire retardant plastic.
If exists thermal fuse will trip and kill off transformer. Thermal fuse is permanent disable, because if it trips, it is considered that temperature was so high that insulation of transformer was compromised, and should not be used anymore even if it seems to work.
Transformer can be designed to fail open.

Primary fuse is there mainly if short circuit does happen, and serves only to avoid your external fuse trip on a power distribution, so it doesn't shut off other devices.

[Richard Crowley]

b) I was disputing someone saying fuses are a requirement, I haven't see anything that states fuses are a requirement and have seen plenty of evidence to show that fuses are not a requirement.

The issue here (as I see it) is not "requirement" as much as "SAFETY" and perhaps "common sense".
Small wall-wart power supplies are by definition low-current, low-power devices. The "old-school" variety that use iron-core, mains-frequency 120V transformers will likely fail quickly when connected to 220V because the primary wire gauge is so small, approaching the wire gauge in a fuse.

Of course, the "old-school" iron-core, mains-frequency transformers are becoming rare as it is cheaper here in the 21st century to use switch-mode power supplies (SMPS). And many (most?) of those SMPS are "universal" to handle anything from 100V (Japan) to 240V (UK) mains voltages.

OTOH it is probably silly to expect common sense here in the 21st century.

Producing a high-power device that is hard-wired for 120V and has a "universal" power inlet connector and NO FUSE is just asking for trouble.  It is trivial to grab a handy power cord and just quickly plug it in. But if you are in a 220-240 part of the world, it results in this kind of nasty failure and potential disaster. 

As a user of Weller soldering gear for over 50 years, I find this kind of short-sightedness to be quite disappointing.  And the typical legal CYA response to be reprehensible and remarkably condescending and contemptuous.