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! :)

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.

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.

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.

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?

"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.

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?

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

Use tape to get up the small sparkly bits

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.

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).

And even this thing has a fuse WELLER!

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.

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.

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

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.

*_Yeehaw 898D_*

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...

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.😉

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.

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.

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.

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.

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

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.

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

Maybe a MCU brown out without a proper watchdog routine.

Well and truly wellered.

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

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.

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.

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

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

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...

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!

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.

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.

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.

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.

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.

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...

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

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.

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 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.

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 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.

NOTE the standard was changed from 240-V to 230-V some 20 years ago, and in Europe, it was changed from 220-V to 230-V Though as you know voltage will fluctuate slightly. And just like a slot-machine the voltage variation can be a current operated money machine for the utility companies.

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.

This is why I personally do never ever recommend cheap tools to beginners. When you do a review and show them that these things work and are usable, these end up in children bedrooms, hobby labs and all other kind of environments where an epic fail like this one cannot be contained properly - especially when the device is handled by an inexperienced person that has never experienced something going south that quickly. Those people might burn down their houses. Devices of such questionable origin should not be recommended to anybody. They are dangerous. I would have expected something like this to have two independent temperature sensors / cutoffs.

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.

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.

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

Got the same trouble on similar device. I turned air flow button to minimum (actually no air flow at all) but temp was set quite high (360°C). Just holding it by hand while talking to somebody, the thing went very bright red and the plastic handle melted. The fact is the heater start heating on the handle side, the end side was probably hot but not reddish and below 360°C, so I guess the sensor at the end of ceramic element without air flow is just useless in this case. Now I know it, and pay attention to always set air to max before hanging on.

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.

This is a good lessons learned for the product designers out there: - solid grounding wire - failsafe in software at every level - thermal cutout (a 20 cent part), even two in series - fail to off state (similar to point two, but in hardware) - always take your gear apart and inspect/modify it before use I'd really wish youtube creators would stop using clickbaity titles, red arrows, flames and angry faces. However, it's youtube's fault for promoting this dumb-down and only they can fix it.

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

Power to the heater is switched off when the torch is in the cradle and the fan keeps going till the temperature falls to 200 deg, if the fan connection was faulty and the torch not positioned properly the heater would not be switched off result meltdown. The heater is regulated by the setting on the front panel not by the blower as suggested by Dave, the blower has a separate speed control on the front panel.

I have a similar one labed Atten 8586. Works for me, doing nearly every soldering with it.

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.

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...

Not appreciating the highly engaging thumbnails.

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!

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

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.

If you buy one of these make sure you inspect it internally before using it they're hit & miss assembly wise

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.

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

Those things are a bit of an adventure. Not for hard use. I bought one, not sure specific name, of just the hot air. Tested reasonable on the fusing and ground, but not upon closer examination. For one thing the neutral was switched, so I swapped that around and ran better ground wires. But they work by fan cooling down to about 100 C. If the fan failed, even if the element shut off, that heat that is usually blown out was trapped and could only go into the plastic. Incident sounded like smoldering plastic, which you can get from just heat dissipation.

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.

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.

I recently got one that looks similar but a bit more modern for 30€ on ebay. Same style with the holder and all. But this one actually turns the heating element off and the fan to full blow until its reached ambient temperature. So a Meltdown is effectively prohibited unless of course the fan controller fails.

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.

I had a soldering station with the same model number 898d+ from a different Chinese manufacturer. It used to crash a lot. Especially on hot air, but usually the opposite was happening. You’d be heating smd and wonder why nothing is melting, then turn your look at the display and it’s blinking with nonsense, and the heat gun is not heating at all!

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

Hook everything up again, power the unit on and see what happens! Looking forward to the "Quick follow-up video"

I use a WEP 853D solder / rework station that includes a power supply and amp tester up to 1 amp. I read that you need to make sure to turn it off at the rear main power switch and not leave them switched on even when the hot air switch is turned off. The hot air guns are reported to fail after long periods of use. It works well for me but I take precautions and dont use it for extended periods. I cannot afford a high end station just yet but will down the track. Maybe upgrading the fan is a move in the right direction until I can effort a better one (and crimping the earth wires & lowering the fuse rating).

I was using my WEP 858D today and had a similar problem... Fan was on full, working at 385 degrees and the next thing I know the barrel where the heating element is was red hot! I looked at the temperature readout and it read over 700 degrees and it's max temp is 500! (all temps in Celsius) I quickly shut it down before it had a complete melt down like in this video. Needless to say a new hot air station is on order, not one of these though... Still going cheap but not super cheap.

Essential mod for these units is install a main power switch. Mine had a hole already cut out for one on the back panel, it was just taped off so a quick install with a 50¢ rocker. Another common failure is the Darlington transistor. I relocated mine off the main board so I could fit it with a larger heatsink. After replacing that though it's been going strong for 5+ years and use it several times a week. Not a pro unit but good enough for the hobbyist like myself. But install that switch or at the very least unplug it when not in use.

08:52 It is mica-glass, you can find it in hair dryer also, it's used as insulator.

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.

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.

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!

I think that termocouple needs airflow to have good readings. It is quite on the side from the heating element. and another aspect is cold side compensation. If it was not reading the correct value the hole device was lot hotter and the readings could be just a way off.

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.

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?

The fan measuring open just indicates the electronics in the fan are not shorted. The only valid test is to power the fan up and see if it runs. It's a brush-less DC motor.

Unfortunately, as we have seen recently, buying a premium brand is no guarantee of safety or reliability. They all seem to rely on one component in the protection system. If that fails then you are stuffed.

It could have been nothing more than dust blocking the openings in the handle, seems likely given it happened just after a move. The issue I see is the thermocouple measurers the temperature of the air flowing over it. No or restricted airflow means the thermocouple is heated less and more of the heat from the element goes through the fibreglass overwrapping into the plastic case. Could have been avoided with another thermocouple or thermistor measuring handle temperature to trigger an ESD state.

Gas central heating boilers in the UK have an air flow switch, which detects when the fan is blowing air into the combustion chamber (or drawing out the exhaust, on older ones -- these were inherently safe against leaking carbon monoxide as the firebox was under negative pressure wrt the room). The air pressure switch must be in the NC position for the fan to start, then a relay latches it on; and the switch must have moved over to the NO position, with the relay latched, for any power to get to the gas valve and the ignition spark generator. Then the gas valve will remain closed if it the flame detector thinks it is seeing a flame when the fan switch first changes over, so it must see a no-flame condition before sending any gas to the burner and starting to spark. There are also two timers: one which allows the combustion chamber to be purged with fresh air before the gas valve opens and the spark generator is energised, and a second which cuts off the gas valve and spark if no flame is detected within a certain time limit. A fan proving circuit similar to that in a gas boiler would have required just one low-operating-force microswitch to detect air flow and one relay, and would have prevented this situation by cutting off the heater if the air was not flowing. (As you say, misplacing the unit on its rest so the off-switch did not activate and then the fan stopping with the heater still active would be hard to notice, especially if the vibration from putting the tool on the rest was what finally finished off the fan. Dry solder joint on coil, broken wire ..... plenty of likely suspects there.) Of course another -- probably even simpler -- solution would have been to fit a one-time thermal fuse in series with the heater, ordinarily cooled by the air flowing past it but heating up quickly if the air stopped.

I suspect the temperature regulation relies on the air flow over the thyristor, without the airflow there would be an uneven temperature in different parts of the gun.

The 120V version has the same 6A fuse. It's probably something they didn't bother to change between 120/240V models.

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