Author Topic: EEVblog #1160 - Weller Responds  (Read 55316 times)

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Offline Electro Detective

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Re: EEVblog #1160 - Weller Responds
« Reply #425 on: December 25, 2018, 08:25:40 am »

FWIW: Behringer equipment had/still has? IEC power sockets with a flippable fuse holder for 120 or 240 volts.

You can buy these chassis mount things for cheap at most electronics stores here, Altronics, Jaycar etc without stuffing about ordering from the big players

If the fuse is in the 120 volt slot for use in the USA, flipping the fuse holder to 240 results in no power to the unit because no fuse is in that slot, and vice-versa

i.e. it's hard to balls that up AFAICT

Someone has to pull out the fuse holder to make any changes, like fit the proper value fuse as indicated on the label for 120 or 240, align it and push in   

I'll be extra optimistic and state that even if there is a mix up of the above, the proper factory installed fuse should blow anyway if the wrong voltage selected
or the torroid or circuit cakes itself at 120 or 240 volts

No fuse is bad news   :scared:

 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #426 on: December 25, 2018, 10:12:17 am »
The transformer itself isn't at fault here, as you cannot expect for it to ... fail safely.
The transformer isn't an overcurrent protection device .. A fuse is an overcurrent protection device.

Like somebody just mentioned, transformers are used in gas discharge lamps as magnetic ballasts which are .... current limiting devices.

What are fuses but thin pieces of wire.

Very likely in your automobile you have a "fusible link" which is just a short section of wire which is of a thinner gauge than the rest of the wiring.
 
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Offline coppercone2

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Re: EEVblog #1160 - Weller Responds
« Reply #427 on: December 25, 2018, 11:36:34 am »
does the thing inside of a fuse look like a normal section of copper wire to you?
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #428 on: December 25, 2018, 12:13:52 pm »
The only problem here seems to be the lack of fuse. No doubt that the correct fuse will blow, as the primary was smoking badly. If the primary windings overheated like that, imagine a fuse!
The current at 220v will double the current at 110v (at the very least).
The transformer itself isn't at fault here, as you cannot expect for it to work under twice the nominal voltage. Nor to fail safely.
The transformer isn't an overcurrent protection device. I don't understand the people that acts like if that was the case. A fuse is an overcurrent protection device.
It was already discussed that fuses aren't always required by the safety standards, because transformers limit the current by their nature. They're essentially a coil, after all. We also shouldn't forget safety standards are designed to protect the user and not the device. This all means it's a little more complicated than no fuse equals bad, especially without knowing anything about the engineering and testing that went into the product.
« Last Edit: December 25, 2018, 12:18:01 pm by Mr. Scram »
 

Online Fungus

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Re: EEVblog #1160 - Weller Responds
« Reply #429 on: December 25, 2018, 01:33:37 pm »
I don't even think the mains voltage is an issue, how many people with 240V sockets on their bench have 120V equipment? That's pretty much a non-issue in the real world.

How many people here have seen equipment burnt out due to voltage surges on the mains supply?

(raises hand)

I have never seen that before, ever, and nobody that I know has ever reported that either.

Jeez, it was only a few pages ago:

https://www.eevblog.com/forum/blog/eevblog-1160-weller-responds/msg2055256/#msg2055256

you need to talk to your utility.

Yep. They actually admitted liability last year after destroying the phone system in my wife's office.
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #430 on: December 25, 2018, 01:48:10 pm »
Jeez, it was only a few pages ago:

https://www.eevblog.com/forum/blog/eevblog-1160-weller-responds/msg2055256/#msg2055256

Yep. They actually admitted liability last year after destroying the phone system in my wife's office.
In all fairness, the arguments for fusing presented so far seem to be increasingly unlikely scenarios requiring multiple failures or massive fuck ups. Apparently 380V coming from the mains did happen, but I can imagine that being a bit outside of what Weller can be expected to reasonably deal with.
 

Offline fsr

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Re: EEVblog #1160 - Weller Responds
« Reply #431 on: December 25, 2018, 01:57:27 pm »
The transformer itself isn't at fault here, as you cannot expect for it to ... fail safely.
The transformer isn't an overcurrent protection device .. A fuse is an overcurrent protection device.

Like somebody just mentioned, transformers are used in gas discharge lamps as magnetic ballasts which are .... current limiting devices.

What are fuses but thin pieces of wire.

Very likely in your automobile you have a "fusible link" which is just a short section of wire which is of a thinner gauge than the rest of the wiring.
Interesting, but they have to be designed to do that, and here it clearly isn't the case.


The only problem here seems to be the lack of fuse. No doubt that the correct fuse will blow, as the primary was smoking badly. If the primary windings overheated like that, imagine a fuse!
The current at 220v will double the current at 110v (at the very least).
The transformer itself isn't at fault here, as you cannot expect for it to work under twice the nominal voltage. Nor to fail safely.
The transformer isn't an overcurrent protection device. I don't understand the people that acts like if that was the case. A fuse is an overcurrent protection device.
It was already discussed that fuses aren't always required by the safety standards, because transformers limit the current by their nature. They're essentially a coil, after all. We also shouldn't forget safety standards are designed to protect the user and not the device. This all means it's a little more complicated than no fuse equals bad, especially without knowing anything about the engineering and testing that went into the product.
Well, it didn't looked like the smoking transformer in Dave's video was limiting the current, right?
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #432 on: December 25, 2018, 02:00:01 pm »
Interesting, but they have to be designed to do that, and here it clearly isn't the case.

Well, it didn't looked like the smoking transformer in Dave's video was limiting the current, right?
Didn't it? Did you ever poke a shorted wire in the mains and did it fail as safely as this unit at twice its rated voltage?
 

Online Fungus

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Re: EEVblog #1160 - Weller Responds
« Reply #433 on: December 25, 2018, 02:18:41 pm »
Didn't it? Did you ever poke a shorted wire in the mains and did it fail as safely as this unit at twice its rated voltage?

We don't know exactly how it failed, Dave pulled the plug out of fear before the 'experiment' ran to completion.
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #434 on: December 25, 2018, 02:27:55 pm »
We don't know exactly how it failed, Dave pulled the plug out of fear before the 'experiment' ran to completion.
There you go.
 

Offline foubarre

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Re: EEVblog #1160 - Weller Responds
« Reply #435 on: December 25, 2018, 03:49:45 pm »
The problem that Dave saw made me look a bit more inside my own weller unit, and mainly, pushed me to check why my tweezers failed for the third time in less than one year.
I am happy i did, because what i found inside really shocked (almost a pun, could be literally) me. That thing was full of shorts and utterly dangerous.
Weller does not deserve any respect, in my own opinion.

For more details: https://youtu.be/_L4Owsz90No
If you have any of them, please check them out as i believe they are actively dangerous.
 
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Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #436 on: December 25, 2018, 04:25:49 pm »
At this point it'd be interesting to sacrifice a couple of units for science. Plug a 110V unit into 230V mains and let the fault run its course until it's properly broken or one of the mains safety devices kicks in. Add a fuse to a second unit and do the same. Compare results. I assume most people debating the possible dangers would be willing to chip in.
 

Offline fsr

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Re: EEVblog #1160 - Weller Responds
« Reply #437 on: December 25, 2018, 07:09:04 pm »
Interesting, but they have to be designed to do that, and here it clearly isn't the case.

Well, it didn't looked like the smoking transformer in Dave's video was limiting the current, right?
Didn't it? Did you ever poke a shorted wire in the mains and did it fail as safely as this unit at twice its rated voltage?
Clearly it didn't, or it won't be smoking like hell. In fact, a piece of wire thin enough, encapsulated so that there isn't any melt metal flying around, is what a fuse is all about. And they work quite well. And also very cheap!
« Last Edit: December 25, 2018, 07:21:41 pm by fsr »
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #438 on: December 25, 2018, 07:14:48 pm »
Clearly it didn't, or it won't be smoking like hell.
Why do you suppose it hasn't if it's smoking? One doesn't follow from the other.
 

Offline fsr

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Re: EEVblog #1160 - Weller Responds
« Reply #439 on: December 25, 2018, 07:26:47 pm »
Clearly it didn't, or it won't be smoking like hell.
Why do you suppose it hasn't if it's smoking? One doesn't follow from the other.
Because it doesn't smokes in normal operation, under the designed current, of course.
In any case, a fuse would have done a much better job at failing under higher currents than normal.
 

Online Fungus

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Re: EEVblog #1160 - Weller Responds
« Reply #440 on: December 25, 2018, 07:28:45 pm »
At this point it'd be interesting to sacrifice a couple of units for science. Plug a 110V unit into 230V mains and let the fault run its course until it's properly broken or one of the mains safety devices kicks in. Add a fuse to a second unit and do the same. Compare results. I assume most people debating the possible dangers would be willing to chip in.

Are you doubting the fuse will make a difference?

Fuses are widely used as safety devices their efficacy isn't usually doubted.
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #441 on: December 25, 2018, 07:29:49 pm »
Because it doesn't smokes in normal operation, under the designed current, of course.
In any case, a fuse would have done a much better job at failing under higher currents than normal.
That doesn't mean the current wasn't limited or limited to the point of failing safely, instead of violently.
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #442 on: December 25, 2018, 07:34:52 pm »
Are you doubting the fuse will make a difference?

Fuses are widely used as safety devices their efficacy isn't usually doubted.
Considering the far-fetched examples discussed here, it'd be good to see the actual difference it makes. Not only whether the device fails safely, but also whether a fuse with the wrong current rating saves the device completely.
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #443 on: December 25, 2018, 10:39:30 pm »
Clearly it didn't, or it won't be smoking like hell.

Go ahead and connect a small piece of .08mm2 or 28awg wire to 240V and see what happens. It will not have time to smoke because it will go POP in less than a second. Of course the current was limited.
 

Offline EEVblog

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Re: EEVblog #1160 - Weller Responds
« Reply #444 on: December 25, 2018, 10:48:09 pm »
In all fairness, the arguments for fusing presented so far seem to be increasingly unlikely scenarios requiring multiple failures or massive fuck ups. Apparently 380V coming from the mains did happen, but I can imagine that being a bit outside of what Weller can be expected to reasonably deal with.

So why do they bother fitting primary fuses to any of their other gear?
 

Offline EEVblog

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Re: EEVblog #1160 - Weller Responds
« Reply #445 on: December 25, 2018, 10:49:45 pm »
What are fuses but thin pieces of wire.

They are thin pieces of specially designed wire that have been carefully designed and qualified to meet their specifications.
 

Offline james_s

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Re: EEVblog #1160 - Weller Responds
« Reply #446 on: December 25, 2018, 10:52:29 pm »
Just forget about the 240V thing, that's such an unlikely real world occurrence that it doesn't matter.

The real reason that a primary fuse is needed (I had assumed it was a mandatory safety requirement) is that transformers can and do fail. The turns are insulated by an incredibly thin layer of enamel, all it takes is a thin spot or a nick, or vibration of the wire due to magnetic forces to create a shorted turn or section of turns. No form of protection on the secondary can protect against this, a fuse on the primary whether built into the transformer or wired as an external part is an absolute necessity, there is no reason not to have one, even if there is absolutely no chance of the input voltage being out of range. With a single fuse on the primary you can protect the transformer itself and provide reasonable protection to loads on the secondary.
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #447 on: December 25, 2018, 11:08:22 pm »
So why do they bother fitting primary fuses to any of their other gear?
I'd love to know more about the engineering decisions made here, but I doubt Weller is going to open up about them. That's why some testing would be interesting. It might answer whether they properly engineered things or saved a few pennies too much at least in those tested scenarios.

Maybe there's occasionally a benefit to having a fuse fitted and they want to make sure less cost sensitive customers benefit. Maybe there's a difference in the transformers used. Who knows?
 

Offline tautech

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Re: EEVblog #1160 - Weller Responds
« Reply #448 on: December 25, 2018, 11:26:31 pm »
Just forget about the 240V thing, that's such an unlikely real world occurrence that it doesn't matter.

The real reason that a primary fuse is needed (I had assumed it was a mandatory safety requirement) is that transformers can and do fail. The turns are insulated by an incredibly thin layer of enamel, all it takes is a thin spot or a nick, or vibration of the wire due to magnetic forces to create a shorted turn or section of turns. No form of protection on the secondary can protect against this, a fuse on the primary whether built into the transformer or wired as an external part is an absolute necessity, there is no reason not to have one, even if there is absolutely no chance of the input voltage being out of range. With a single fuse on the primary you can protect the transformer itself and provide reasonable protection to loads on the secondary.
This ^ and only this !
Why in the case of a mains transformer soldering station would you design/engineer anything different ?
Secondary side fusing ?  :bullshit:

One would also wonder so to reduce BOM for a worldwide sold station why a single design 120/240 configuration with appropriate fusing wasn’t made ?  :-//
Avid Rabid Hobbyist
 

Offline fsr

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Re: EEVblog #1160 - Weller Responds
« Reply #449 on: December 26, 2018, 12:32:19 am »
Because it doesn't smokes in normal operation, under the designed current, of course.
In any case, a fuse would have done a much better job at failing under higher currents than normal.
That doesn't mean the current wasn't limited or limited to the point of failing safely, instead of violently.
It didn't fail safely. That's a massive amount of smoke, and that means heat, and that means something is burning, and that something is the enamel, which is the only isolation of the windings inside the transformer. That amount of smoke can trigger a smoke detector, and with good reason.

Are you doubting the fuse will make a difference?

Fuses are widely used as safety devices their efficacy isn't usually doubted.
Considering the far-fetched examples discussed here, it'd be good to see the actual difference it makes. Not only whether the device fails safely, but also whether a fuse with the wrong current rating saves the device completely.
What "wrong" current rating? This soldering station would likely have a 0.8A to 1A primary fuse, if they bothered to install one. If it's connected to 240v instead of 110v, that means at least twice the normal current, and in practice likely more.
In any case, if the enamel burns before the fuse blows, that sounds like a badly chosen fuse to me. Of course in this case there was no fuse, so it's not surprising that the thing smoked.

I live in a 220v country, and i seen some 110v equipment connected to 220v. And we are talking about the lowest quality chinese computer AT and ATX PSUs with a 220/110v switch here. Of course, they didn't work again without repairs, because the power transistors failed, but nothing smoked as badly as the transformer on the Weller.

I even have a 110v Epson LX-810 lying around that my brother connected without the 220 to 110v transformer, and back in the day i opened it without much hope, but only had to change an internal fuse and it worked again.

Anyways, it would be interesting to check exactly what fuse do reputable soldering stations normally have. If there is a datasheet for it, that's good data to check.
 


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