For those asking, I checked the TRIAC. It hasn't failed short, but it doesn't detect as a TRIAC with the Mtester (possible not enough current for that). Quick follow-up video coming shortly.

Probably taking over the Weller mentality: everything is a fuse if you use it wrong enough.

This is why every bench needs an "Explosion Containment Pie Dish" for just such an emergency! :)

The reed switch doesn't control the fan, the temperature feedback loop does. It keeps running for a minute or so after the handle is put on the rest. If the fan stopped as soon as the handle was put down, then it was certainly a fan failure.

If the thermocouple is the only sensor in the handle, then without airflow, you obviously can't detect the runaway fast enough, as you will be relying upon convection only. So the plastic (in the base) will melt long before convection gets the thermocouple (at the exit) up to the set point of, say 400 degress C. Other strategy(ies) will be required.

Dave, pay David so he can buy a decent rework station! ;)

Not vibration isolation but seal to force all air forward.

Why not a more hands on look into the problem instead of just speculation? You didn't even show a multimeter in this video. New lab not setup enough yet to hook up to the heating element, re-solder the fan and power it up and check things and actually determine where the failure was? Or just not worth your time?

Yeah, I have one of these (similar), and the thermal sensor is in the path of the airflow (where you'd want it to be). You only care what the temperature of the air is during operation, not the coil (until it goes meltdown). Likely, a thermal fuse on the coil would be what you want. I could tell because if I set the airflow to near zero, the coil would just turn on all the time and get quite toasty in a hurry.

I suspect the triac is the original fault, shorted out so the element didn’t power down when it was put back in the cradle, so the controller tried to shut it off and turned off the control signals for the fan and element, but if the triac shorted the element wouldn’t be able to have its power shut off.

I never actually measured it, but wouldn't a brushless DC fan always measure open circuit since there's a bunch of transistors between the supply an the stator?

"sol dering station" is probably because the other side is "smd rework station" - they just separated both words after 3 and after another 6 characters. With smd rework, it fits fine. With soldering, it fits only after the second break, but hey, if you don't know how to read our characters, if you only know how to read Chinese, it would be just as hard as it is for us trying to write something in Chinese and getting it right.

The temp sensor would be expecting such high temps as its in the airflow section on the blower, its used for temp select not as a safety device, it was probably regulating the temp as spec but without the airflow the heat just built up in the handle.

While a 6A fuse may have been over-rated for the application, a more appropriate 4A fuse still wouldn't have changed anything about the hot-air wand melting down from fan failure as the element was likely operating normally at the time. The fuse only does any good when something fails in a way that causes excess current draw long enough to blow it. A bit puzzled about why the temperature regulation didn't reduce the heater's duty cycle after the fan stopped. Did the TRIAC or thermocouple short out? I know my similar-looking cheapo hot-air station is pretty quick at throttling heater power when I change airflow.

And even this thing has a fuse WELLER!

Use tape to get up the small sparkly bits

Ive got the same gun. I always stare at the temp to make sure its cooling down when it put it in the holder.

I think you got yourself a fake one. I live in China and have a genuine Yihua station. The fan is supposed to keep spinning when you place it back in the holder, only the heater should stop. Depending on the starting temperature, the fan should keep spinning for a couple of minutes until the sensor measures about 50 degrees C. Also: the plastic shell looks nearly identical but the inside of mine is completely different. The PCB is different and the magnetic sensors (there are multiple in mine) are not simply glued to the housing. The heating element is replaceable as well.

My Atten 858D+ v3.0 also does the same thing if I have it in my hand (fan and heating element are working) and then press the middle "store/call" button. The fan stops working and the temperature shoots through the roof, smoke included. Took me couple of seconds to realize what's going on so I quickly changed the temperature which caused the fan to start again. Firmware bug.

19:23 this fan is bldc, it have own driver on board. You can't verify it like that!

Could it be possible there is a malfunction with the Triac? Don't know much about them, but wow, surprising it failed like that. Terrible!

Maybe a MCU brown out without a proper watchdog routine.

"Input fused. There you go Weller." Shots fired.

*_Yeehaw 898D_*

I sure hope that the white insulation material isn’t asbestos!

My school outfitted their lab with 853D's (which feature the same heatgun, etc. + power "supply") I've seen a few of them meltdown in a similar manner. There's a software bug (in the 853Ds we had) : if you keep cycling it between active/holstered in a short amount of time the processor locks up and stays in a random-state {(fast) heating up, steady w/ fan, cooling off, off}. The workaround was to listen for the fan to shut off on holstering. If immediate then switch the unit off then on again, and don't leave anything heat-sensitive where the holstered heat gun is pointing. (Was actually convenient when shrink wrapping stuff.) OFC with sixty hot airguns to choose from, this wasn't a serious issue, unlike the input filters starting smoldering fires because of an inappropriate component choice(?) Those all got replaced/retrofitted before being installed so I can only guess what the TI changed.

Heat regulation keeps the output at a set temperature, if the fan fails the output temp stays the same but there is no cooling air to protect the plastic from melting. The heat which is normally carried away finds it way back to the plastic housing. Seems like a second temp sensor would be a good safety feature.

Faults pretty clear to me. The thermocouple is a good 10mm away from the element wire. When the fan blew, there was nothing but convection and conduction to move hot air past thermocouple; it was no longer being forced past. This would make it take a reasonably long time for the thermocouple to register the true temperature of the element, certainly longer than it took for heat to conduct through that thin insulation and the metal can. Looks like they needed a separate thermal cut out in closer proximity to the element to catch an overheating scenario with no airflow

So as I am considering one of these as a hobby station for occasional use, the build quality of this seems sufficiently good. A fan burning out after 3 or 4 years of substantial use doesn't seem to be a show stopper, especially if one turns the unit off at the switch rather than flapping the red hot thingy around in mid air while wondering wtf to do, haha.

David and Dave, well now you have a transformer for that Weller. WEP and Weller colab. 😂😂😂😂

18:50.. Since so many of us have one of these WEP rework stations... why not get a functioning one and put it through some possible error conditions to see where it will/may fail ??? Then find a solution to the fail so what happened to David won't burn down our homes. Just quickly looking at it I can see adding a parallel reed switch to the opposite side of the hand held unit and perhaps a Thermal cutoff switch right at the element supply. BTW.. my 858D has been working flawlessly for the past 4 years.

Well and truly wellered.

Not appreciating the highly engaging thumbnails.

Bucket of Sand. It's old school but a bucket of sand is great for electronics fires like Dave had and it's not as much of a commitment as breaking out the fire extinguisher.

Thanks for an interesting post mortem! Just a tiny note from an ex cable manufacturer: Quite unlikely that you would find 8 strand wires. The geometries favor 1 center & 6 around, which equals 7. The next one, used for more flexible wires would be 19 strands, (1+6+12).

7:10 because red color means where electrons are flowing from.... duh everyone knows that electrons are blue

I had the same one for 8 years or so. A month ago, I picked up the soldering iron, and I could see it was glowing a dull red and I could feel the heat radiating a foot away. Dumpstered it and got the pace one you reviewed. It was quite an upgrade.

I'm glad this video came out. I was given this soldering station (US version) as a gift a year or so ago and once had a similar problem occur. I had the fan on the lowest setting with the most restrictive nozzle on the hot air gun and the temperature skyrocketed to I think 550 degrees C while it was just preheating. Thankfully I caught it before it could get any hotter as I had the unit resting on a wooden table. I currently don't have the money to buy a new soldering station but am wondering if it would be possible to add in a toggle switch in the heat gun to manually toggle the element off when I want it to cool off.

The station I have right now is similar to this one, but when the handle is but back into the holder it instead turns the airflow to the max (in addition to turning the heating off), so I guess they have at least attempted to give it a better chance of survival...

Never leave the area when this tool cools down, keep an eye and an ear on it, a nice trick is to slightly increase the fan speed, and it should cool down more rapidly. Great tool for the price. I also often rotate the tool until i see temperature decreases...

It seems the triac or whatever is driving the triac failed. That's why the reed switch responded and turned off the fan and the temperature feedback sensor couldn't turn off the element. They should include a physical thermal cutoff switch near the element to prevent this.

On my YiHUA 898 D+, when cradled the blower stays on until the temperature is below 100 and orientation doesn't matter. Features that Davids did not seem to have.

I've got one of the similar model (YiHUA 8786D I believe) for my first year in college. Back then it only cost me ¥200(~$30) or so for both a rework and a soldering station, which was quite an affordable price for amateur student hobbiests like me. The station works pretty fine for a year, before I decided to go 'professional' and bought a ¥150(~$22) standalone T12 soldering station. But the rework function of that YiHUA model is still used until now, which helps me get through a great amount of troubles in the past year without any failure, and that magnet is actually very sensitive and reliable. One thing I've noticed is the temperature sensor on the airgun is not directly mounted to the heating element, which is quite reasonable because it is supposed to measure the heat of the airflow, not the heater. That means it requires the heat to transfer through the air gap before the sensor can sense it, and with the absence of airflow the heater can heat up dramatically before the sensor reach the target temperature. Another thing is that the airgun still blow air to cool down after it is placed back onto the holder, which means it is very easy to spot a fan failure at the scene, and you probably don't want to leave things like this working away from the scene. Anyway, you get what you pay for, don't expect too high on a cheap model, otherwise the producer won't get enough profit to survive.😉

I also have a 898D from another company, and one of the greatest dangers of those devices, is that they will start when removed from the holder, EVEN IF YOU SHUT THEM DOWN FROM THE CONTROL PANEL. And by the way, mine had no information sheet whatsoever to tell ma about this magnetic switch behaviour - which made me thing first that it had spurious restarts until I realised it was when I removed it from the holder...

You two gave me really good laugh, I wish there will be more videos of this kind :)

Weller : Fuses are overrated. Meh. WEP : Meh. Over-rate the fuse.

I wonder why there is no thermal fuse to be found, though.

the fan does not stop when its on the cradle until it reaches 100 degrees so he should have known something was wrong as soon as the fan stopped and the degrees had not counted down

I had almost exactly the same thing happen a few months ago. Same WEP brand. It was an air-only model. I set it on the cradle, and a few seconds later I heard a POP and my lights flickered. I looked over, and the whole metal part of the blower was orange hot. I am absolutely sure that the fan was still running. I hit the power switch immediately and unplugged the unit from the wall. There was no smoke or flame. I took the handle apart and there wasn't any noticeable damage to anything. There was a small spot up on the metal casing that *looked* like the heating element had shorted and created a weld. I took the chance and tried turning it on again in a safe location. The fan ran but the heater did not come on. "Fortunately" mine was only a couple weeks old and I was able to return it to Amazon for a refund. Looking in forums afterwards, I read some of the best advice for these: It's good for the price but only use it in the middle of your driveway with a fire extinguisher handy.

Hi Dave, Sounds like you had fun having a sidekick in the studio. Fun! :)

Does the thermocouple only detect well when there is air flowing over it - ie the fan is going!

I have the Atten branded one. As soon as you put the handle down, the reed switch cuts the power to the heating element and the fan keeps blowing until the elements goes down to 100 C and then stop. So even with a fan failure, overheating of the element cannot be explained as it gets no power when the handle is down. It would just take more time to cool off.

Is the thermal couple working? I have one of these soldering iron dead years ago. That it for 5 years. Now you are making me think to upgrade. What is a reasonable chinese one just with hot air. Have Weller soldering stations and a royal ask a back up.

I have a model 855D and mine has the soldering iron heat gun and a variable voltage supply. I bought it new off ebay for $89 and have used it the last 6 months and have had no problems whatsoever. It's possible to get a Lemmon every so often.

Is it possible to put some kind of alarm circuit on the fan that would light an LED or trip a piezo so you know?

Often the fan in mine doens't turn on when I remove it from the stand, but the element does.

I have this soldering station and had what seems to be the exact same failure. The fan stopped working and the element would keep heating up. Luckily the reed switch still worked so I put it down and turned it off. After replacing the fan, the station is still working and in use about 3 years later... I think it might be time for an upgrade

Dave, the Quick 857DW+ is a really nice hot air station, much better than the 898D. It is roundabout 110 USD. It would be a nice addition to the lab for sure.

Shouldn't there also be a last-resort one-off thermal fuse to kill power to the element if the handpiece goes above its operating range? I think they include them on electric kettles and things like that, with something like two springs joined by a blob of temperature-specific alloy.

no airflow so the hot air didn't get to the temperature sensor?

Could it be that the fan motor itself went bad? I'm surprised this has happened, since I have an identical unit which I've been using for over 10 years, yet haven't had a problem with it. The reed switch is a bit finicky, so care must be taken when putting the heating head back on the cradle.

A thermal fuse inside the housing would have saved it from melting, along with a software change and you're good to go. All David needs is a new hot air gun, a thermal fuse and you'll have it up and running in no time. I think they designed it to be pointing down when in the cradle which isn't very ergonomic, next one, cover the cradle in magnets.

I had the same unit for ages, the fan on mine stopped working within a few years. I simply replaced it with a better quality fan. I since upgraded and gave the unit to a family friend. Who to the best of my knowledge still uses it.

My auto shut of is starting to fail I put it on the holder a few times and had to keep playing with before it starting to work again.you can by replacement heat blowers on Ebay ,I may have to do that or replace the whole unit.

even if it has an overheating protection in software i think the termocouple was not able to detect temperature because of its position. It seems to be placed inside the ceramic insulation and in contact only with the hot air, so no air no temperature

SCR went short hence the thermal control was lost. Also the fan has control electronics and cannot be measured as a coil..

The way the thermal sensor is placed, without air blowing through, how accurate would be the sensor? Circulation and conducting are minimal, so the only major heat transfer would be radiance, right? Could take a while to heat the coupling up enough to trigger a shutdown.

Purchased a year ago. I found it did not always seat properly in cradle to shut down and no cable disconnect for the hot air rework like for the soldering iron. Definitely should never be left unattended, unless completely unplugged!

I have the same Yihua board based station. I've seen some stations burned by the triac, that's why I never leave the handle on the holder when the hot air switch is on. When I turn the hot air switch off its cools down also, but the switch is turns off the heater physically, not through the triac, that's why I'm sure my station won't be burned like this. I was thinking to put some additional relay protection in the station, which can switch the heater off when the fan is stopped, but I don't think I really need this now.

More like a "Smol-dering Station", am I right?!?

This is a shame, because I was really looking at getting one of these. I absolutely love my TS100 and I have no problem using it as my main iron, it's displaced my need for a soldering station, but I need a hot air rework station, and I figure I might as well get a soldering iron in the mix as well, especially if it uses Hakko tips. Any budget stuff you *would* recommend?

i have one of the ebay ones it has a temp up to 480 degrees and the fan will stay on until the handset is down to 100 degrees before shouting the fan off so it may have been just to hot with no air flow to cool it down

The thermal couple was properly located beyond the last coil of the output. But when the fan cut off and the tool was docked, it was at the bottom of the heat coil. As heat rises, the cool air is drawn into the nozzle passing over the thermal couple telling the processor to increase heat. Even if the thermal coupling was working fine, the heater housing would be kept far hotter than designed.

There will have been significant heat build up after hours of use and the fans probably cut out too soon. I set mine to minimum flow when I put it back so that the heat has more time to dissipate from right inside of the thing. A fast fan flow would cool the surfaces and then shut down with more heat to be released.

I do wonder if there may be something wrong with the position of the thermocouple. Because the way it is mounted it may just look at the temperature of the air around it, and not the temperature of the heating element. So if tried to keep the temperature of the air but if there is no airflow (if the fan breaks or ...), then it would overheat the element and still think that the temperature of the element is ok.

there should be a temperature fuse in the heating element, should be rated for around 500C, so if the fan does fail the element wont get too hot. that is why my X-Tronic unit says to keep the fan speed knob above 5 for temperatures over 400C.

do any product connect N and ground? here both is live so that will be catastrophic.

I had something similar off eBay. threw it before plugging it in. fused on neutral. Metal case not earthed. Ended up in the scrap board bin. Used an Aoyue 968A+ for years since and more recently a Quick 861DW for heavier duty stuff.

I am thinking of rewiring of my 858D. Mains switch should physically cutoff power from the heating element. I know, it means using larger switch. I have 858D for six years and have no problems, but I ran into similar issue with same optocoupler (optotriac) used here, which sometimes (and I do not know why) turns on and stays on despite the fact that diode part of it is unconnected and stays in this weird state until the triac side is disconnected. Then it returns to normal. It's rare, but it happens. I am using central switch to cutoff everything on my table, so the soldering station is most of the time disconnected from the AC, but it's not good feeling to know that there is only silicon switch (with weird optocoupler) between AC and heating element.

Sounds a bit like my DSE temp controlled iron. In '79, I picked it up from the bargain table for a few dollars as a faulty unit and soon found the thermocouple had shorted to the heater, sending 22VAC to the input of the op-amp. New barrel, chip and zener diodes later I had a cheap iron that still works today. By the looks of the melted spot on the chip, I'd say it went with a pop and released the magic smoke.

also you can get a model that does not countdown and stays at the set temp or you can modify your unit so it does not switch off when on the cradle which this one may be, as the reed switch should have turned the heater off

I enjoyed the tear-down. Thanks for the entertainment. I wouldn't trust that micro in a socket unless it was a machined-pin socket. A few years and a bit of oxide and the thermocouple might not get read, or the heater shutoff reed switch might not get read. But I just bought one that looks very much like this one so I believe I'll pop the lids and do a bit of PM on it and put a mark on the shell of the wand where the reed SW is. My bench is going to look pretty silly with one of these sitting next to my trusty old Metcal iron, but I retired before I got very far into SMT work, so any new SMT soldering gear is consumer grade. But thank you for pointing out where I should do a bit of upgrading on it.

We also have the genuine YiHau 898D+ workstation.Had it for many years. We mainly use the soldering side of the setup. Touch wood nothing like this has happened to our setup yet.

I wonder how close this model is to the Xtronic 6040? They look near identical. I know i had this exact problem with the air gun on the Xtronic 5040-xr3, but i chalked it up as improper use because it was in a unmonitored student lab at at my university. Where some thought you melted the wires to solder something.

I've got one of these that's so old it doesn't even have branding on it (there's a blank space where a logo would go, and the model code 898D+). I have no idea if it still works since I rarely ever used it. But thanks for the warning, I'll be sure to make sure it doesn't go supernova whenever I use it next.

I suppose, whithout airflow the thermocouple was not properly heated and that caused bad things. For the next video you can get the same Rework Station, add external switch to the fan, and see what happens with thermal regulation if you turn off the fan for some time while it is working.

I could not see in the video checking the fan motor with a 24v supply. So how can you be so sure it failed?

I had something with almodt the same handle but it blows until it cools to 80c before shutting off

Hey Dave, you should check out the Soldron 878D. It has the exact same setup. Even the same mould and holder for the hot air gun. I think it's just one of these that are rebranded and sold here in India. I've been using it for a while too now but after seeing this, it made me wonder if I should switch.

I think the problem is due to the position of the thermal sensor, it is far from the resistor and when the fan broke, read less temperature than the actual temperature of the resistor!

Had this happen to mine several years back, looks almost exactly the same! I thought I'd just forgotten to turn it off (which is true) but I didn't realise there's also a reed switch in the body that's supposed to help in that situation...

I use a WEP 952D+ as my main hot air station. The compressor ones have a protection. If it runs the heater but no response from thermocouple it throws an error and shuts off, also if it loses the thermocouple it throws an error and shuts off.

It's obvious based on David's description. He said the fan cut off, but not the heater. The fan is not supposed to stop when placed in the holder. It only stops when the temperature drops below a level, like 100 degrees. This means the fan failed, or a fault in the circuit providing power to the fan. The reason it overheated is because the reed switch was not activated so the heater remained on. The temperature sensor position measures the hot air blowing over it. Without the air blowing, there would be a huge temperature difference between the heater and the sensor.

I have a no name version of this and so far over the last few months it has worked great. I do only use the hot air for heat shrink though.

I think what happened that the fan stopped working and the sensor detected the temperature increase so it set the heater to the lowest setting but without air flowing it wasn't low enough because it probably wasn't programed to deal with a fan failure.

I have the TENMA branded hot air, almost identical. I want to hate it so I have an excuse to buy the quick. But I can't, it just keeps on working, and works very well. Just wish the cord was silicone.

Just remember to put the heat gun fan face downwards when you put it in the the holder then it will air cool and turn off, if you put it in fan face upwards its still runs and at the temperature you set it at.

Where does it start spewing flames?

one problem I noticed is that the temp probe requires airflow for proper sensing. it wouldn't explain this fail because it would have sense the temp before it went completely nuclear but it could be a contributor.

The exact thing happened to my station (YIHUA 8786d). It's within warranty but they are not honouring the warranty. Will changing the fan solve the issue? .. I desoldered the fan and checked it ... It's not working..... Or is there a problem with the circuitry ?