Author Topic: EEVblog #1160 - Weller Responds  (Read 158262 times)

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Offline thm_w

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Re: EEVblog #1160 - Weller Responds
« Reply #650 on: January 03, 2019, 11:54:21 pm »
DJ's souved and dissected Weller carcass should be retrieved from the ---Bin Of Unfused Shame--- and reassembled with a suitable 120/120 CT to 24 volt isolation transformer

($35 to $60 depending on VA requirements  > any decent cheapie tranny should be better enameled than the honey coatings on the crusty deceased one,
and come stock with a thermal fuse fitted with a  -MUST- recommendation to use a primary fuse and the value. Reference: Altronics and Jaycar catalogues)
...
I'm betting a properly rated fuse will pop faster, perhaps crack or shatter, and the unit will survive unscathed and back to work

Yeah I agree for sure the unit will survive. What killed it was heat, not overvoltage. The windings would have been tested for well over 240V during manufacture.
But to properly test it, you'd want to use a high voltage isolation test, before and after.

Daves concern was certainly valid though, if it did heat up or smoke at all there is a risk the insulation is damaged.

Its the combo of bodged in secondary side fusing and no primary side fusing that doesn't inspire confidence.  The secondary side polyfuse positioned where the transformer can heat it is IMHO legitimate to reduce the risk of cooking the transformer as line voltage polyfuses aren't cheap or common, but why in the nine billion names of god is the extra ordinary fuse on the secondary side not the primary side?

I argued against this earlier in the thread, there is no thermal coupling from PTC to the core or windings at all, so I don't think it will do much.
There is a reason when a thermal fuse is used on a transformer it is either buried inside the windings or directly coupled to them then tape over top.

Some estimations:
Fuse is 7A (trip of 14A), and secondary is using approx 3A (peak), so 20% of rating. A PTC curve shows we would have to hit over 115C to reduce the fuse rating to 20%, who knows what the winding temp would be at that time, over 200C? I don't think anything could cause the transformer to heat up that much and not already be blowing up/burning something else already.
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Offline EEVblogTopic starter

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Re: EEVblog #1160 - Weller Responds
« Reply #651 on: January 04, 2019, 12:08:31 am »
The bottom line is that Weller can't admit they've done something wrong (for potential liability reasons); I'm actually surprised that a lot of people here think that the response wouldn't have been pretty much exactly what it was.

It could have been worded a LOT better without giving them liability.
 

Offline EEVblogTopic starter

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Re: EEVblog #1160 - Weller Responds
« Reply #652 on: January 04, 2019, 12:12:34 am »
Common sense tells us that something which is apparently so blatantly bad should be easy to prove, but no real quantifiable evidence has been brought forward. Considering this has been going on for many pages now, you have to wonder why this evidence is consistently absent. That there is no real issue seems ever more likely. Angrily disagreeing doesn't change that. Providing something tangible does.

For the dozenth time now, and I'll keep saying it every time someone brings it up, if there is no potential issue then why does Weller have a primary fuse on almost all of their other (identical function) products?
 

Offline EEVblogTopic starter

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Re: EEVblog #1160 - Weller Responds
« Reply #653 on: January 04, 2019, 12:14:19 am »
Its the combo of bodged in secondary side fusing and no primary side fusing that doesn't inspire confidence.  The secondary side polyfuse positioned where the transformer can heat it is IMHO legitimate to reduce the risk of cooking the transformer as line voltage polyfuses aren't cheap or common, but why in the nine billion names of god is the extra ordinary fuse on the secondary side not the primary side?

The secondary side actually has two fuses, plus the polyswitch. One is on the PCB.
 

Offline EEVblogTopic starter

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Re: EEVblog #1160 - Weller Responds
« Reply #654 on: January 04, 2019, 12:17:19 am »
All for the sake of a few cents in the BOM of a product which is being promoted using $100,000 stands at large trade fairs (alongside competitors who've seen Dave's video and will happily tell their clients about it).

I'm waiting for some smart competitor to realise the marketing potential here and a make video with one of their product designers tearing down their product and showing how they have a primary side fuse and how they select the rating and test it etc, and how they take safety more seriously than their competitor  ;D
 

Offline Ian.M

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Re: EEVblog #1160 - Weller Responds
« Reply #655 on: January 04, 2019, 12:24:38 am »
Its the combo of bodged in secondary side fusing and no primary side fusing that doesn't inspire confidence.  The secondary side polyfuse positioned where the transformer can heat it is IMHO legitimate to reduce the risk of cooking the transformer as line voltage polyfuses aren't cheap or common, but why in the nine billion names of god is the extra ordinary fuse on the secondary side not the primary side?

I argued against this earlier in the thread, there is no thermal coupling from PTC to the core or windings at all, so I don't think it will do much.
There is a reason when a thermal fuse is used on a transformer it is either buried inside the windings or directly coupled to them then tape over top.

Some estimations:
Fuse is 7A (trip of 14A), and secondary is using approx 3A (peak), so 20% of rating. A PTC curve shows we would have to hit over 115C to reduce the fuse rating to 20%, who knows what the winding temp would be at that time, over 200C? I don't think anything could cause the transformer to heat up that much and not already be blowing up/burning something else already.
If the transformer is running hot from near continuous operation at full load, which would heat it up fairly slowly, an appropriate polyfuse will probably save the day by tripping on the full load current due to its elevated temperature and enforcing a cooling off period till it resets.  Its presence is probably an indication that Weller undersized the transformer for average duty cycle rather than speccing it for worst case 100% duty cycle operation,e.g. due to setting max bit temperature to make a long sheet metal joint that will be an excessive thermal load on the bit.  However, if it does in fact have a 7A carrying current, and 14A trip current, it sounds like Weller FUBARed  its selection as well.

The polyfuse wont do *anything* for rapid heating due to a short-circuit on the output - its just too poorly thermally coupled to the winding.   It also cant protect against overheating due to saturation or a shorted turn because its downstream of the possible fault!

Of course what they should have done is either add a safe duty cycle limit for the transformer in the controller firmware, removing the need for a polyfuse, or use an adequately rated transformer for 100% duty cycle operation in the first place . . .

The secondary side actually has two fuses, plus thepolyswitch. One is on the PCB.
Yes. hence my description of the black wire ended one as the 'extra ordinary fuse'.  Knowing that there's a fuse on the PCB, its sheer presence hanging off the secondary terminal indicates a design process SNAFU.

Did anyone note the ratings of all the fuses?
 

Offline EEVblogTopic starter

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Re: EEVblog #1160 - Weller Responds
« Reply #656 on: January 04, 2019, 01:22:57 am »
The secondary side actually has two fuses, plus thepolyswitch. One is on the PCB.
Yes. hence my description of the black wire ended one as the 'extra ordinary fuse'.  Knowing that there's a fuse on the PCB, its sheer presence hanging off the secondary terminal indicates a design process SNAFU.
Did anyone note the ratings of all the fuses?

Both are 4A. Why you'd have two 4A fuses in series is beyond me.

 
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Offline Electro Detective

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Re: EEVblog #1160 - Weller Responds
« Reply #657 on: January 04, 2019, 02:57:30 am »
All for the sake of a few cents in the BOM of a product which is being promoted using $100,000 stands at large trade fairs (alongside competitors who've seen Dave's video and will happily tell their clients about it).

I'm waiting for some smart competitor to realise the marketing potential here and a make video with one of their product designers tearing down their product

and showing how they have a primary side fuse and how they select the rating and test it etc, and how they take safety more seriously than their competitor
  ;D

plus demonstrating their unit surviving a 120 to 240 volt    'not entirely 100% user error'  IEC style snafu scenario   

...and mentioning (with URL links) a recent Youtuber down on his luck in this regard, with a competitors product,
and the communication that followed  :palm:

I envisage competitor and fused knockoff sales bolting within weeks, 
Ebay servers grinding to an athritic snails pace flooded with 'Make An Offer' auctions on unfused Wellers

Not that the Sellers will mention the lack of fuse protections in the Description, and just roll with the 'Weller quality' thing...  ;)

If they're going for almost landfill prices, I'll buy them (and a bag of fuses and temperature thingies),
stock up the bench, toss one or two in the tool bags, flog a few modded ones on EEVblog...

I have no doubt the quality will be Weller style, and keepers once fused up  :clap:

 

Offline Warhawk

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Re: EEVblog #1160 - Weller Responds
« Reply #658 on: January 04, 2019, 08:48:15 am »


SCNR  ;)

This is a very sad picture of a typical German Lötplatz. I've been around many labs in Germany since 2010 and all of them suffer from the same phenomenon - all soldering stations set to the highest temperature (typ. to 450°C). Ideally in combination with the smallest tip and flux impossible to find or a dry out flux pen. I mean WTF Deutsche Entwicklern? The WW2 is over, you can reduce heat back to normal. |O
Surprisingly, I am not the only one who recognized this. I always feel like an alien when bringing my own tips, flux and solder with me.

Offline Wolfgang

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Re: EEVblog #1160 - Weller Responds
« Reply #659 on: January 04, 2019, 09:07:33 am »
The secondary side actually has two fuses, plus thepolyswitch. One is on the PCB.
Yes. hence my description of the black wire ended one as the 'extra ordinary fuse'.  Knowing that there's a fuse on the PCB, its sheer presence hanging off the secondary terminal indicates a design process SNAFU.
Did anyone note the ratings of all the fuses?

Both are 4A. Why you'd have two 4A fuses in series is beyond me.

Its a mistake. They wanted to have them in *parallel*.  >:D
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #660 on: January 04, 2019, 09:50:58 am »
Please don't intentionally misattribute quotes to people.   :--
I did not. You simply didn't comprehend what I said.  :--
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #661 on: January 04, 2019, 10:12:20 am »
the owners of Weller soldering irons now know that there's a safety issue.
No, they don't know. They are pretending. But feel free to point to actual safety issues, for which the device has been certified against.
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #662 on: January 04, 2019, 10:31:36 am »
For the dozenth time now, and I'll keep saying it every time someone brings it up, if there is no potential issue then why does Weller have a primary fuse on almost all of their other (identical function) products?
Say it as many times as you like. It doesn't make it any more true that there's an issue with this stations OR all the other appliances out there without a fuse as you seem to suggest.
 

Offline Wolfgang

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Re: EEVblog #1160 - Weller Responds
« Reply #663 on: January 04, 2019, 10:52:06 am »
For the dozenth time now, and I'll keep saying it every time someone brings it up, if there is no potential issue then why does Weller have a primary fuse on almost all of their other (identical function) products?
Say it as many times as you like. It doesn't make it any more true that there's an issue with this stations OR all the other appliances out there without a fuse as you seem to suggest.
Dave, dont worry. Darwinism will take good care of these people.  >:D
« Last Edit: January 04, 2019, 10:53:57 am by Wolfgang »
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #664 on: January 04, 2019, 03:24:01 pm »
For the dozenth time now, and I'll keep saying it every time someone brings it up, if there is no potential issue then why does Weller have a primary fuse on almost all of their other (identical function) products?
The answer is the same as the last few times. :) Added to those replies the question can also be reversed. Why would Weller remove the fuse in one specific model and even just a regional variant as I understand it if they obviously have plenty of experience with them? That suggests there's a deliberate design decision and possibly some engineering. You can't just assume it's just penny pinching, even though that's certainly a possibility. It's likely they quantified the problem and may have concluded the actual issue isn't that big.

Like I said the last few times, I'd love to know more about the process involved but I doubt Weller is going to open up about it.
« Last Edit: January 04, 2019, 03:54:01 pm by Mr. Scram »
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #665 on: January 04, 2019, 03:33:31 pm »
Nope.

The problem is that post-Dave's-video, the owners of Weller soldering irons now know that there's a safety issue. If they have any sort of a conscience then they have to be a lot more careful about selling/giving them to random strangers.

It's not just a simple case of them not working when they arrive after a mixup, it's about them going up in smoke within seconds of being plugged in.

Would you still sell them on eBay, knowing what happens?
I must be misunderstanding you, because claiming the soldering stations go "up in smoke within seconds of being plugged in" is preposterous and demonstrably untrue. That didn't happen when Dave originally reviewed the unit and isn't what users are reporting.

Claiming there's a safety issues because there's no fuse is strange too. Many devices are sold without fuse and the safety regulations don't require it either. We've also discussed before that as far as we can tell it was a safe failure. A safe failure isn't a safety issue. It didn't run its entire course, but nobody so far has been willing to put his money where his mouth is to contribute to a few of these units to do a full test. We're really going around in circles with the same arguments being rehashed.
 

Offline SeanB

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Re: EEVblog #1160 - Weller Responds
« Reply #666 on: January 04, 2019, 04:52:52 pm »
With regard to the car analogy, look at any of the Russian dashcam channels, where you are witness to all ages of vehicles, from the 1940's inspired Trabant, trolley buses, light commuter rail in the streets, to the latest from all the car manufacturers. They all meet each other in all sorts of accidents, and in general, because of car safety technology, the drivers and passengers walk away generally alive, though the vehicle is a wreck. Contrast to the early cars, where the car would be in an accident and would be fine, just the driver would be dead.

Biggest take away from there is that pretty much every SUV will roll over in an accident. Safety technology costs the manufacturers some money, but is worth it.
 

Offline Fungus

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Re: EEVblog #1160 - Weller Responds
« Reply #667 on: January 04, 2019, 04:57:27 pm »
A safe failure isn't a safety issue.

Smoke pouring out is not a safe failure.
 

Offline floobydust

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Re: EEVblog #1160 - Weller Responds
« Reply #668 on: January 04, 2019, 05:02:57 pm »
The secondary side actually has two fuses, plus thepolyswitch. One is on the PCB.
Yes. hence my description of the black wire ended one as the 'extra ordinary fuse'.  Knowing that there's a fuse on the PCB, its sheer presence hanging off the secondary terminal indicates a design process SNAFU.
Did anyone note the ratings of all the fuses?
Both are 4A. Why you'd have two 4A fuses in series is beyond me.

The secondary fuse + PTC combo... I'll give a perspective and hope the thread S/N ratio stays up there.
From an engineering, physics point of view, if the fuse clears first- the PTC can do nothing. If the PTC trips first, the fuse can do nothing. It doesn't make sense.

With only a secondary fuse, a problem is passing the transformer overload heating tests and short-circuit test.
 
Generally, the transformer is long term tortured at the fuse trip point OR the protective element (PTC) can trip and hold.
Without the PTC, 61558-1; 15.3.2 test is constant current 210% times the fuse rating for one hour, then checking temperatures, insulation etc. which is 4A*2.1 or 8.4A very high hence the need for the thermal fuse to pass this.
UL 1585; 27.1.2b  "... {with} positive temperature coefficient device (PTC), the current is to be measured after 5 seconds of operation."

Here, the PTC gives a lower test current, passing is easy but skirts the transformer's lack of protection.

UL 1585; 27.2 "... Protective devices are to be shorted out during this test."
It doesn't say all or both devices and may be why a second fuse is present. Even the transformer short-circuit test, where the secondary is shorted... must have been done after the terminal pins, after the windings.

I'll check if I have access to UL 5085 -  Low Voltage Transformers safety standard which would apply for the US. It's an old standard with some issues:
"During the regular review and maintenance cycle of the harmonized standards, it was noted that there were several areas in the standards where the requirements were either redundant and/or not clear or that additional clarification is needed. Revisions to the standard to correct the above stated deficiencies also included corrections to typographical errors."  CSA Urgent Bulletin re: C22.2 No. 66 and UL 5085
Proof these old standards have cracks and loopholes and engineering common sense should be used.   
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #669 on: January 04, 2019, 05:11:56 pm »
Smoke pouring out is not a safe failure.
Didn't we discuss this before? If it were to be massive amounts of smoke it may be a problem, but a failure being absolutely smokeless isn't required. Smoke doesn't preclude a safe failure. Contribute to the test units and we can see how much smoke is produced.
« Last Edit: January 04, 2019, 05:14:30 pm by Mr. Scram »
 

Offline Fungus

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Re: EEVblog #1160 - Weller Responds
« Reply #670 on: January 04, 2019, 05:24:11 pm »
Smoke pouring out is not a safe failure.
Didn't we discuss this before? If it were to be massive amounts of smoke it may be a problem

Dave's words were "big wide billow of smoke" and "...by the amount of smoke that escaped from this thing, it's not going to be pretty".
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #671 on: January 04, 2019, 05:29:36 pm »
Dave's words were "big wide billow of smoke" and "...by the amount of smoke that escaped from this thing, it's not going to be pretty".
I think he also reported the smoke detector not going off despite it happening the office building, but maybe hecovered up the sensor. I'm not sure.
 

Offline Fungus

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Re: EEVblog #1160 - Weller Responds
« Reply #672 on: January 04, 2019, 06:17:05 pm »
Dave's words were "big wide billow of smoke" and "...by the amount of smoke that escaped from this thing, it's not going to be pretty".
I think he also reported the smoke detector not going off despite it happening the office building, but maybe hecovered up the sensor. I'm not sure.

Grab the rubber glove, quick!  :-DD
 

Offline fsr

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Re: EEVblog #1160 - Weller Responds
« Reply #673 on: January 04, 2019, 06:41:24 pm »
How do you guarantee the safety of a transformer that smoked the enamel of it's primary windings? That stuff is isolating every winding. It's no surprise that pretty much everyone else, including weller on more expensive models include a well-known safety device: a fuse.

Unless weller reponds something that makes more sense, i will think that they removed the fuse for strictly economical reasons. If weller had some kind of transformer that didn't needed a fuse, why would they use it only on their cheapest models? Because the more expensive ones do have the fuse, which wouldn't be needed with the "better transformer from the cheapest models". How would a blow-proof transformer cost less than a fuse anyways?

Makes no sense.
 

Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #674 on: January 04, 2019, 06:59:22 pm »
How do you guarantee the safety of a transformer that smoked the enamel of it's primary windings? That stuff is isolating every winding. It's no surprise that pretty much everyone else, including weller on more expensive models include a well-known safety device: a fuse.

Unless weller reponds something that makes more sense, i will think that they removed the fuse for strictly economical reasons. If weller had some kind of transformer that didn't needed a fuse, why would they use it only on their cheapest models? Because the more expensive ones do have the fuse, which wouldn't be needed with the "better transformer from the cheapest models". How would a blow-proof transformer cost less than a fuse anyways?

Makes no sense.
I understand that line of reasoning, but it's equally valid when reversed. Why would Weller risk putting out a dangerous product if it's that easily fixed? It makes no sense, so maybe there's more to it.

It's possible the failure modes Weller identified and quantified are found to be increasingly unlikely. I think I read somewhere in this thread the 230V model is fused and the 120V model isn't? That suggests they've identified some kind of difference in regards to the risks there.
 


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