I have a 12v 80mm fan, super chinesium, same design, i pushed it to about 55V, it didnt die, but it started overheating above 20-22V. I dont think it died from overvoltage as the chip seems quite resilent but im sure it died from being overheated for so long
This is not actually a bug, but a feature! The MCU detected a fan failure so it blew up the heater while you were in the vicinity so it wouldn't burn your house down in case you left it plugged in.
I find DaveCAD works better with the graphite powered human interface device. The rolling-buffered Ink-HID often enables write-protection accidentally. [edit: and yes the last one is also write once, read only]
I still think that the lack of airflow meant that the thermocouple was measuring possibly 1 hundred degrees or so less than the actual temperature. The other factor might be the magnetic switch when you put the thing down - because if the fan failed, you might think it had switched off when seated back in the cradle. You wouldnt be aware that what had happened is the fan died, and the station thought the tool was still being used (ie. not disabled by the reed switch - I often find I have to reseat mine a few times to get it to register that I've finished using it). That coupled with the temperature measured as much less than actual temperature perhaps caused ramp up in current provided to the element in order to compensate as it thought it was too low... In any case a bad design, these things need to consider failure of each individual component and how it might be fatal.
This is exactly what happened, the thermocouple isn't close enough, the heating element get hot from it's center, you can see it by where the metal gets red first, the distance is big enough so the set temperature will never be reached.
The MOC opto-coupler gate driver fails as well. Just this week I replaced a TRIAC that was conducting without external signal and that fail to correct the problem, it was only when I replaced the MOC3041 that the behavior went back to normal. Testing the whole driver circuitry is a good idea...
This is my next suspect as well. Is there a signal on the isolator's output? Input? MCU? Does the signal from the thermocouple make it to the MCU's input? Are the thermocouple's wires shorted or open? Any of those things could cause the triac to get stuck always-on. Given that fans rarely quit out of the blue under normal circumstances, maybe an over-voltage killed the fan and other stuff on the control side.
If your main AC is 230V than it will happen again, in Germany standart is MOC3063, because MOC3041 can't handle the peak voltages, but many manufacturers still use MOC3041, don't know why, there is no difference in price.
But there is no need for all that, because the problem that caused this all is what he says in the first seconds of this video, but dismisses it, because he is over-qualified to know the heating element is heating from it's center and without airflow the heat on the thermocouple is ways lower, so the system will keep on heating but never can reach the set temperature. So instead to resolder the two wires of the fan, check it's transistor and replace the housing of the handle, he decided to screw the whole station completely.
@@Wilson84KS I will say it again, MOCs are fragile and can fail in a way that keeps the TRIAC on all the time. Without proper checking the whole driver circuitry you can't say that's the fan that caused all that mess.
10:42 - _"We can control the turn on and turn off time of this TRIAC."_ You can only control the turn on time. The TRIAC will continue conducting until the "end" of the phase when the current becomes too low. Oops... ;-P
Hi Dave, This testing circuit will not work properly ... You will feel it is going from ON to OFF suddenly .... The reason is A1 and A2 ... A1 should be down and A2 is up ... The gate is referenced to A1 not A2 so the voltage should be higher than A1 to trigger properly the Traic .... Good Luck
Maybe. Could have been the (incorrectly specced) supply voltage, or maybe some form of SCR latchup (ironically) that could have killed the chip, or something else. The diode and RC filters would be there for a reason.
I love ya Dave! You always give me a chuckle. When I finally do make it to australia, (been wanting to go for 35 years) I definitely want to buy you a pint!
I've had a TRIAC fault where there was a partial short from gate to anode which was enough to keep it switched on regardless of the gate signal. There was no short from Anode to Anode.
If I owned it, I’d definitely be adding a bi-metal thermal overload in series with the heating element... couple dollars and 5 minutes work might save your house or life...
Should have had a three wire fan. The third fan wire for sense or feedback. The heat element would not have been allowed to come on or remain on without receiving the Fan sense or feed back signal from the fans third wire.
Looks like some very loose windings on one of the coils in the fan, did one break away? I'm guessing the handset was thrown down into its rest, which dislodged one or more of the fan coils, and likely damaged the thermocouple. I believe if the thermocouple goes open circuit, the controller will just deliver 100% power to the heater constantly. The drive circuit is quite similar to the one in my cheap chinese desoldering gun, which was shipped to me with a broken heater, and the seller shipped me a replacement heater element (with built in thermocouple). On installing the new heater, i failed to notice that one of the precrimped thermocouple wires was not stripped properly, and crimped down on the insulation, making it open circuit. When i turned it on the thing glowed white hot. I yanked power and attached the thermocouple properly and it works great.
@@ernieschatz3783 Watch the _other video_ before commenting, he said he "measured that fan and it showed open circuit", suggesting he used continuity mode on a multimeter. But that wouldn't be representative, since the fan is driven by an IC the multimeter's low voltage wouldn't suffice to make it start doing anything. So when testing that way it could very well be showing "open circuit" even if it worked fine.
I still dont think there was any failure other than the fan, the rest of it could still function correctly and overheat to the point of melting the plastic. I suspect that if you just put the mains power on the heating element without any control the element would burn out very quickly possibly before the thing got so hot as to melt the plastic that much.
Did you check out the reed switch to see if it was damaged? If the fan failed, the heat could have risen enough to thermally cause the reed to open, maybe? If so, then that switch opening would signal the unit to turn on the heating element
Guys... Everyone touts DaveCAD as some great, free, open source CAD tool, but don't y'all realize it's free because of _micro-transactions!_ It's totally true! The software might be free to play, but you have to keep buying the DaveCAD media! That's where the paper industry makes all it's DaveCAD cash! I've seen prices from $0.95 a piece, all the way up to big lootboxes (with random colored media) that cost $15 and up! Crazy, I tell ya! :P
Watching around 10:40 when you changed the gate resistance. It didn't look like the top half of the waveform went off where the bottom half did. I would expect both half cycles to be affected evenly. Wondering if one of the SCRs in the triac is bad.
Waiting for Triac-testing part 3 since there was some issues with the testing procedure. Also want to see measuring the coils of the fan. There are so many things that you exclude in the videos that at least i want to see when diagnosing. Still i have no evidence what went wrong. Just some guessing.
Inside the motor driver there’s a diode in series with the VCC. You checked it with an ohmmeter. The diode might not conduct with the ohmmeter. Did you test it with power?
It could have been the control loop. I have played with the firmware and replaced the micro on on my atten 858d+, and I remember even with full airspeed, full trottle on the heater ramps up the temperature really quick. If something goes wrong with the regulation it will go red hot even with the fan on, i think. I bought some thermal fuses, but found no good way to mount them in the heater module.
IF the TRIAC failed that requires more failures to also happen to cause this. The fan does *NOT* stop until the sensed temperature is below 100° (I believe. At least on my 858D+.) thus the fan would continue going full speed (whatever it was set to) until it has cooled down. A thermocouple error is a different story and could cause this. Note that even when set to the max temperature of 450° AND max air flow that the heater is not on continuously. Now consider if the flow was set low but the thermocouple is now reading low (and thus never getting to the set point) how hot it will get with 100% heater duty cycle. The situation gets even worse if a small nozzle is installed. I believe this is what may have happened.
Hi Dave! I did some work on TRIACs. One very common reason why they stop turning off is if they are on square wave power supply like old style inverters or UPS. They need time to turn off which they get on sign wave as it goes through zero crossing. There is almost 1ms time during 50Hz power line. While 50Hz square wave do not give this time for TRIAC to turn off! It do not damage the TRIAC but give 100% duty cycle to the load! Can you verify the state of power supply at the time it went kaboom!
Dave, why didn't you just connect the whole station as it was to the heat gun, just with the heater replaced with a light bulb? Then you could check if it controls the fan and reacts on thermocouple temperature.
Test the thermocouple. I had a weller that wound up turning the power on to the iron full time and it turned out the thermocouple had failed open circuit.
hey dave, yesterday i watched ur tutorial playlist, and i found this video unlisted for some reason in the playlist tutorial, just want to let you know
The failure mode with these is quite simple. The fan is individually controlled and there is no feedback. The thermal regulation is done by a microcontroller using the couple and triac. When airflow stops, the airflow from the heating element to the thermocouple also stops, making the thermocouple read low less, causing the heater to switch fully on. Since the heat will never quite reach the thermocouple to get it to the set temperature, this thing will go full meltdown. All it would have needed is fan rpm sensing and maybe even a thermal fuse in the heater block.
Great video! Interestingly, the vacuum tube (valve) equivilent of the SCR was called a thyratron which may be where the term thyristor was derived from. I worked on a radar system the used hydrogen thyratrons - yes a tube filled with hydrogen gas - to switch high voltage DC ( 15 Kv @ up to 600 amps). The tube was manufactured by EEV, an English valve manufacturer.
Are these devices not designed to antisipate situations like a fan stopping. Maybe there should be a tiny tachometer attached to the fan to give feedback to the microcontroler.
Yes....also my first reaction....measure the Fan coils. 😏. By the way..i have the same only Atten heatgun station for years....still working fine....i would like to buy an expensive Weller....but then i have to put and build an extra fuse on it.... 😏
Dave, I downloaded and installed DaveCAD, but Im having trouble getting my Papermate graphics and line tracing hardware to work. Any ideas? Are there additional plug-ins I need? Also I updated to Inkjoy, if that helps.
thanks for the davecad link dave. i am actually running an old system from before yearcount. its a ‘ stone and chisel 200-bc’ . had some installation issues before but working grate after the update. i was wondering.. will you be putting in an undo function anytime soon ?
David should write to the manufacturer pointing out the safety failure and ask them what they intend to do to fix their design. They sell a lot of these units and it is only a matter of time before a bad accident happens.
So what is left to explain the failure of the overtime circuit than that the thermocouple requires airflow? Especially given that the TC is behind the last bulkhead of the ceramic insulator, I think this is a likely cause. Do you plan to test the TC in situ?
curious if the magnet in the holder interfered with the hall effect sensor. David did mention that it was intermittent so maybe hand piece not locating correctly in the holder
Probably not. The magnet in the holder is a constant magnetic field, the hall effect sensor picks up a changing magnetic field. The constant offset shouldn't harm anything.
Should have tested the hall sensor to see if that was the fail point. I might have to change the fan in mine to avoid a similar failure even though it is a later model it won't hurt to check.
I have one of these. I think what happened is that the reed switch didn't initiate the shutdown sequence. In which, the fan stays on until it is cooled down to 100C. it was probably just doing it's thing as normal, not knowing it was supposed to shut down. And David, hearing the fan stop didn't think anything of it, and thought it cooled down enough, and it just kept heating up because it didn't know it was supposed to be off. With the fan going, it cools the entire heating coil, which makes the circuit pump a lot of electrons into it. Without the fan going, it no doubt spiked in temperature very quick.
I'm thinking the fan failed, this caused the heat to rise on the reed switch (their normal operating range is -40 to 200 C), which reduces the magnetic force on the contact arms so it opens, which causes the heating element to come on, which adds more heat. Secondary vector is the heat reduced the strength of the magnet in the holder. And if the reed switch wasn't right on the magnet... Needs a physical breaker for the element power if the fan is not running when temp is above 100C
i'd replace it anyway, even if it was just a hand unit failure. most of the triacs in these aren't too expensive, so it just makes sense to make sure its going to be okay. with a new handheld bit, it should be right as rain.
Make sure to only download original DaveCad™ software from the vendor website. You can check the authenticity of your product by examining the logo, it should have a letter D with a small face drawn inside of it.
I don't think it's a SW bug. The SW knows temperature of the air going out but it don't know about air flow, presure or fan speed. And the air don't conducts the heat very well. The SW thinks "OK, it have 200 degrees C, user wants 350 so I put it to the full power to heat up". No way to detect somethink is wrong. It is definitely HW bug - missing thermal fuse as a last safety components in case of the failure (how much it costs in mass production?), missing feedback from the fan (as used on PC CPU fans), use HAL sensor above specified voltage.
At which temperature? In normal use they get pretty hot to get the airflow at 500 degrees even with an environment of less then 10 degrees C. Glowing-hot I guess on the element, actually you see it glowing quite clear when they are in normal use. A hairdryer is just getting 'warm' compared to this. If you had one, where to install? Maybe at 2000 degrees C, close to the core but in which direction? Before it reacts when it is on the bottom of the heater, much plastic will have been melted already, probably shorting out the contacts or making a connection with the mains to the metal (death trap for electrocution) or you have to get a real expensive one. And that will be the main reason... heating handle inclusive transport over the whole world is about 5 -10 Euro's -not much room for expensive safety-things...
Can ya test the coils? I watched till the end to see if the coils were actually bad, or a transient took out the hall effect chip. Wonder if the filtering circuitry that was left out was responsible for filtering out any reverse transients from the coils somehow.
So, does this mean the driver failed, but the motor is fine? I know you hooked it up the power supply, but if you hooked up the motor bypassing the driver would it work? Curious, not sure how these work.
I have a version of this. The iron and rework station actually work quite well. But I had to fix things before use (like they fused the ground instead of mains) and I installed a quality mains switch from Mouser. Still, I never leave it plugged in, because I don't trust it 😆
YT had a video replay from a security PVR in someones house showing one of these cheap tools catching the bench on fire. I tried searching for it but couldn't find it... could someone post the title, if they've seen it? The owner just made it to put-out the fire.
Airflow. I have the smd rework from sparkfun which features a diaphram air pump with adjustable flow. Turned down the flow for a minute with the temp still hot, which was already hot for what I was doing, and found the plastic which was in direct contact with the steel had melted and the tip sagging. Haven't let it do this since and it has not gotten worse. I'm sure the airflow provides a thermal barrier between the element and the steel encasing it.
Anyone know why the first thing checked was not the thermocouple and its wiring back to the processor? If the thermocouple actually failed first and it thought it was cold, would that not have shut the fan off? I know the fan is dead now but i would imagine a vast proportion of the heat generated after the initial fault happened would have exhausted out of the fan side as it is the pass of least resistance as it has bigger holes than the nozzle.
It is likely that without the resistors and capacitors installed as specified in the data sheet, transient voltage spikes hit the driver chip and popped it.
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.
Yes, that's it, the difference between set and is temperatures is without airflow big enough so the set temperature will never be reached, the heating element heats from it's center when there is no airflow, clearly visible by the glowing on the metal pipe, so the difference is huge.
QUESTION ! ! ! The bearing in the center of the motor at the end, was that "wallered" out by wear or did it get warp by the teardown? Worn bearing in motor cause it to hang up on something prevent it from turning? My guess actual cause was motor but it failed mechanically not electrically. Set it down but instead of sense it off it actually locked the motor. Sorry I know bad wording.
My guess is that the fan failed and the radiant heat was too much for the plastic. Dave, if I am not mistaken you have a similar rework station : disconnect the fan and let it sit for 30 mins ;)
The visible damage is a result of the failure. It seems that you have not yet found the "why" pointing to the root cause. Several more "why" cycles are probably needed...
He mentions it right at the beginning but is obviously too smart to realise that without airflow the gap between set and is temperature id high enough so the set temperature can never be reached, he just say the thermocouple is close enough and dismiss this possibility, because also too much engineer to know the heating element is heating from it's center, right there where the metal pipe begins to glow.
I have some Stagelighting-Dimmerpacks that utilize the BTA16 and I must say everytime a Dimmerchannel blew up on me it resulted in the Triac staying on, dead short leaving the lights at full intensity. It’s an easy fix though by simply changing the damn thing but still every single one of the countless times it has happened failed in its on-state
2 simple modifications could have prevented the meltdown. 1, A thermal fuse in the heating element. 2, and RPM sensor on the motor itself. If the motor doesn't run, the heater doesn't come on, or turns off. I would also recommend a warning buzzer, To indicate a possible dangerous failure.
Splicing in a thermal fuse would be the easiest way to make the device a bit safer, but thermal fuses are notoriously unreliable. Considering the high temperature it normally operates at a thermal fuse would only cut power after it's already on fire. The "annoying" problem is thermal fuses can gradually fail when they operate slightly below their temperature limit. After a couple hundred hours it may just decide to cut power even if nothing was actually overheating. Fans can be manufactured with a locked rotor sensor (instead of RPM). This type is frequently used in DLP projectors with HID bulbs, because they could burst into flames if a fan stopped working. For a device that doesn't monitor RPMs this is the easy way to add safety logic to cut power when a fan dies. If anything, I'm impressed by how good the WEP station is at such a low price. I'll probably buy one in the future and modify it.
i recently decided to buy a "my first" rework station and glad i decided against this one. i noticed about 5 different "brands" with this same form factor and thought twice about it.
its not uncommon in 3D printers to have the thermister fail open and the MCU attempt to heat the heater back up and cause thermal runaway thats why under temp protection is so important
On a 3d printer with the proper firmware, the printer will refuse to heat if it can't sense the temperature, if the temperature is too high or too low.
unfortunately this feature tends to be disabled to prevent false triggers another even lesser used feature is the hotend not heating up when it should be to indicate a thermistor or heater cartridge that has fallen off all fairly simple to implement in anything like this
Fan fail - I wonder if the fan wires are cheesy aluminium and one has gone o/c maybe - you could stick 12v directly on the fan board and just check it still doesn't spin up Dave (I noted the comments above about fan chip voltage range also)......But it seems odd that we have two failures happening at the same moment here, so I wonder if something in the power supply has gone intermittent and is knackering multiple things, like fan and triac drive/control loop at the same time ?
Hi Dave, Could you make a video about using transconductance on a multimeter ? I have an Escort 99 multimeter I bought on eBay is pretty much the same as the keysight U1252. I manual show measuring resistant but doesn't do anything. Could you believe that there is nothing about it using that feature on multimeters.
3.5-16v supply voltage ic , on a 24v fan together with the missing RC filter and diode, i wonder that not more burned up like that
LOL, didn't notice that!
@@EEVblog no wonder it failed lol
I have a 12v 80mm fan, super chinesium, same design, i pushed it to about 55V, it didnt die, but it started overheating above 20-22V. I dont think it died from overvoltage as the chip seems quite resilent but im sure it died from being overheated for so long
I was wondering the same thing
@@EEVblogIs that white thing (in the fan) not a fuse? If you trace it out that's pin 1 (+) of the chip, but prolly the chip is gonesky
This is not actually a bug, but a feature!
The MCU detected a fan failure so it blew up the heater while you were in the vicinity
so it wouldn't burn your house down in case you left it plugged in.
Being white hot was the safety feature so anyone could see it was failing.
I'm using DaveCAD and so far I love the software! Simple, clean! No whackers!
Simple yes. but sadly nu updates.......
I find DaveCAD works better with the graphite powered human interface device. The rolling-buffered Ink-HID often enables write-protection accidentally. [edit: and yes the last one is also write once, read only]
@@muppetpaster Don't need em, no bugs, every needed feature included...
@@juliandahl1999 Oh beware....it might become obsolete! hahaha
It requires a high quality perefiral, mine one is glitching all the time.
I still think that the lack of airflow meant that the thermocouple was measuring possibly 1 hundred degrees or so less than the actual temperature.
The other factor might be the magnetic switch when you put the thing down - because if the fan failed, you might think it had switched off when seated back in the cradle. You wouldnt be aware that what had happened is the fan died, and the station thought the tool was still being used (ie. not disabled by the reed switch - I often find I have to reseat mine a few times to get it to register that I've finished using it). That coupled with the temperature measured as much less than actual temperature perhaps caused ramp up in current provided to the element in order to compensate as it thought it was too low...
In any case a bad design, these things need to consider failure of each individual component and how it might be fatal.
This is exactly what happened, the thermocouple isn't close enough, the heating element get hot from it's center, you can see it by where the metal gets red first, the distance is big enough so the set temperature will never be reached.
The MOC opto-coupler gate driver fails as well. Just this week I replaced a TRIAC that was conducting without external signal and that fail to correct the problem, it was only when I replaced the MOC3041 that the behavior went back to normal. Testing the whole driver circuitry is a good idea...
This is my next suspect as well. Is there a signal on the isolator's output? Input? MCU? Does the signal from the thermocouple make it to the MCU's input? Are the thermocouple's wires shorted or open? Any of those things could cause the triac to get stuck always-on.
Given that fans rarely quit out of the blue under normal circumstances, maybe an over-voltage killed the fan and other stuff on the control side.
If your main AC is 230V than it will happen again, in Germany standart is MOC3063, because MOC3041 can't handle the peak voltages, but many manufacturers still use MOC3041, don't know why, there is no difference in price.
@@Wilson84KS My main AC is 127V
But there is no need for all that, because the problem that caused this all is what he says in the first seconds of this video, but dismisses it, because he is over-qualified to know the heating element is heating from it's center and without airflow the heat on the thermocouple is ways lower, so the system will keep on heating but never can reach the set temperature. So instead to resolder the two wires of the fan, check it's transistor and replace the housing of the handle, he decided to screw the whole station completely.
@@Wilson84KS I will say it again, MOCs are fragile and can fail in a way that keeps the TRIAC on all the time. Without proper checking the whole driver circuitry you can't say that's the fan that caused all that mess.
Thanks for explaining what a triac is, it helps not so experienced viewers like me understand everything!
Thanks for refreshing my old knowledge of the TRIAC!
Thanks for taking the time to go through our own ideas and proving proof of your own.
The fan chips data sheet said max 16v and somebody gave it 24v - Ooops! That YHFS fan was NOT labeled correctly...
Yep, bad labling. Not sure what voltage they actually drive it at though.
10:42 - _"We can control the turn on and turn off time of this TRIAC."_ You can only control the turn on time. The TRIAC will continue conducting until the "end" of the phase when the current becomes too low. Oops... ;-P
Hi Dave, This testing circuit will not work properly ... You will feel it is going from ON to OFF suddenly .... The reason is A1 and A2 ... A1 should be down and A2 is up ... The gate is referenced to A1 not A2 so the voltage should be higher than A1 to trigger properly the Traic .... Good Luck
Why ? Have you tried that ? I tried that many times and this is my conclusion
@Marcin Berman very funny
ما شاء الله ربنا يبارك فيك معلمي الفاضل
@Marcin Berman wut?
A silly question:did you check the optocoupler?
Your wide-range precision resistance substituter has surpassed its re-calibration due date 😉
The magical smoke didn't escape, she'll be right.
I wonder if the motor drive IC eventually failed because they didn't add the RC filters?
Maybe. Could have been the (incorrectly specced) supply voltage, or maybe some form of SCR latchup (ironically) that could have killed the chip, or something else. The diode and RC filters would be there for a reason.
I love ya Dave! You always give me a chuckle. When I finally do make it to australia, (been wanting to go for 35 years) I definitely want to buy you a pint!
Many many thanks 😊 🙏
I've had a TRIAC fault where there was a partial short from gate to anode which was enough to keep it switched on regardless of the gate signal. There was no short from Anode to Anode.
If I owned it, I’d definitely be adding a bi-metal thermal overload in series with the heating element... couple dollars and 5 minutes work might save your house or life...
Isn't the temperature sensor a thermocouple, not a thermistor ?
Did I say thermistor? Oops.
@@EEVblog Yes, even a few times in a row...
Should have had a three wire fan. The third fan wire for sense or feedback. The heat element would not have been allowed to come on or remain on without receiving the Fan sense or feed back signal from the fans third wire.
Looks like some very loose windings on one of the coils in the fan, did one break away?
I'm guessing the handset was thrown down into its rest, which dislodged one or more of the fan coils, and likely damaged the thermocouple. I believe if the thermocouple goes open circuit, the controller will just deliver 100% power to the heater constantly.
The drive circuit is quite similar to the one in my cheap chinese desoldering gun, which was shipped to me with a broken heater, and the seller shipped me a replacement heater element (with built in thermocouple). On installing the new heater, i failed to notice that one of the precrimped thermocouple wires was not stripped properly, and crimped down on the insulation, making it open circuit. When i turned it on the thing glowed white hot. I yanked power and attached the thermocouple properly and it works great.
I can't believe, you have actually uploaded pics of sticky notes into a Git Hub. I can't wait to see some new commits on that. :D
Did you actually try the fan with a power supply? You mention is as if you just tested continuity, but that's not representative...
Try watching the video before commenting
@@ernieschatz3783 Watch the _other video_ before commenting, he said he "measured that fan and it showed open circuit", suggesting he used continuity mode on a multimeter. But that wouldn't be representative, since the fan is driven by an IC the multimeter's low voltage wouldn't suffice to make it start doing anything. So when testing that way it could very well be showing "open circuit" even if it worked fine.
I still dont think there was any failure other than the fan, the rest of it could still function correctly and overheat to the point of melting the plastic. I suspect that if you just put the mains power on the heating element without any control the element would burn out very quickly possibly before the thing got so hot as to melt the plastic that much.
Very useful given I've a very similar station. Cheers Dave!
I'll add my vote for a video on going down the rabbit hole on the workings of a TRIAC. Explaining the quadrant thing etc. Cheers
3:12 Hi Dave, can you give us the download link for the nice and cute "DaveCAD" Software :-D
Did you check out the reed switch to see if it was damaged?
If the fan failed, the heat could have risen enough to thermally cause the reed to open, maybe? If so, then that switch opening would signal the unit to turn on the heating element
make video about triac and teach us young players!!!
Guys... Everyone touts DaveCAD as some great, free, open source CAD tool, but don't y'all realize it's free because of _micro-transactions!_ It's totally true!
The software might be free to play, but you have to keep buying the DaveCAD media! That's where the paper industry makes all it's DaveCAD cash!
I've seen prices from $0.95 a piece, all the way up to big lootboxes (with random colored media) that cost $15 and up! Crazy, I tell ya! :P
You wouldn't believe my commission
*Sent from my private jet flying to my private island*
Watching around 10:40 when you changed the gate resistance. It didn't look like the top half of the waveform went off where the bottom half did. I would expect both half cycles to be affected evenly. Wondering if one of the SCRs in the triac is bad.
They aren't separate SCR's as such, it would just be imbalance in the gate current thresholds.
Waiting for Triac-testing part 3 since there was some issues with the testing procedure. Also want to see measuring the coils of the fan.
There are so many things that you exclude in the videos that at least i want to see when diagnosing. Still i have no evidence what went wrong. Just some guessing.
You just need to watch carefully.
Open circuit on fan.....
And the issues raised with the test are pointless.... the triac works...
Probaby the red fan cable was broken and the holder did not activate the reed switch that stops the heater.
Nice explanation Dave
Inside the motor driver there’s a diode in series with the VCC. You checked it with an ohmmeter. The diode might not conduct with the ohmmeter. Did you test it with power?
Wonder if the hall sensor flagged a fault to the main board to do a total shutdown?
It could have been the control loop. I have played with the firmware and replaced the micro on on my atten 858d+, and I remember even with full airspeed, full trottle on the heater ramps up the temperature really quick. If something goes wrong with the regulation it will go red hot even with the fan on, i think. I bought some thermal fuses, but found no good way to mount them in the heater module.
IF the TRIAC failed that requires more failures to also happen to cause this. The fan does *NOT* stop until the sensed temperature is below 100° (I believe. At least on my 858D+.) thus the fan would continue going full speed (whatever it was set to) until it has cooled down.
A thermocouple error is a different story and could cause this. Note that even when set to the max temperature of 450° AND max air flow that the heater is not on continuously. Now consider if the flow was set low but the thermocouple is now reading low (and thus never getting to the set point) how hot it will get with 100% heater duty cycle. The situation gets even worse if a small nozzle is installed. I believe this is what may have happened.
Are there any sensors to detect fanfailure ??
Hi Dave! I did some work on TRIACs. One very common reason why they stop turning off is if they are on square wave power supply like old style inverters or UPS. They need time to turn off which they get on sign wave as it goes through zero crossing. There is almost 1ms time during 50Hz power line. While 50Hz square wave do not give this time for TRIAC to turn off! It do not damage the TRIAC but give 100% duty cycle to the load!
Can you verify the state of power supply at the time it went kaboom!
what's about the triac in the "white" opto-triac ???
To To You mean phototransistor?
@@johnfrancisdoe1563 Yes
Dave, why didn't you just connect the whole station as it was to the heat gun, just with the heater replaced with a light bulb? Then you could check if it controls the fan and reacts on thermocouple temperature.
Because that is a repair mans mind - Dave, brilliant as he is, just hasn't got one of those as shown on many of his 'repairs'.
Hello, where should the oscilloscope probes be connected? to avoid short circuit
Could a short in the fan disable the control loop by overloading the low voltage supply?
Would need to reverse engineer the circuit to see.
Dave measured the motor resistance with a multimeter it was open circuit.
It is now open circuit, but that doesn't mean, it failed short and then due high current something burned and turned open circuit.
@@morantaylor Well that pretty much settles that.
Yes, it adds the extra thermal resisrtance between heater ane the heat sensor.
Test the thermocouple. I had a weller that wound up turning the power on to the iron full time and it turned out the thermocouple had failed open circuit.
What is the processor locked up, and it kept outputting a PWM signal without reading inputs anymore
hey dave, yesterday i watched ur tutorial playlist, and i found this video unlisted for some reason in the playlist tutorial, just want to let you know
The failure mode with these is quite simple. The fan is individually controlled and there is no feedback. The thermal regulation is done by a microcontroller using the couple and triac. When airflow stops, the airflow from the heating element to the thermocouple also stops, making the thermocouple read low less, causing the heater to switch fully on. Since the heat will never quite reach the thermocouple to get it to the set temperature, this thing will go full meltdown.
All it would have needed is fan rpm sensing and maybe even a thermal fuse in the heater block.
Great video! Interestingly, the vacuum tube (valve) equivilent of the SCR was called a thyratron which may be where the term thyristor was derived from. I worked on a radar system the used hydrogen thyratrons - yes a tube filled with hydrogen gas - to switch high voltage DC ( 15 Kv @ up to 600 amps). The tube was manufactured by EEV, an English valve manufacturer.
Are these devices not designed to antisipate situations like a fan stopping. Maybe there should be a tiny tachometer attached to the fan to give feedback to the microcontroler.
what I am missing is a simple resistance test on the 2 coils of the stator. Did one fail ? we want to get to the bottom of this surely ;)
Both measure ok (100 ohms)
Yes....also my first reaction....measure the Fan coils. 😏. By the way..i have the same only Atten heatgun station for years....still working fine....i would like to buy an expensive Weller....but then i have to put and build an extra fuse on it.... 😏
Dave, I downloaded and installed DaveCAD, but Im having trouble getting my Papermate graphics and line tracing hardware to work. Any ideas? Are there additional plug-ins I need? Also I updated to Inkjoy, if that helps.
well that advice is good,but bleeding! obvious. Trap for young players is forgetting tongue direction and depth!
thanks for the davecad link dave. i am actually running an old system from before yearcount. its a ‘ stone and chisel 200-bc’ . had some installation issues before but working grate after the update. i was wondering.. will you be putting in an undo function anytime soon ?
Thank you!
Your bench illumination looks good! Did you manage to install your lights as before?
David should write to the manufacturer pointing out the safety failure and ask them what they intend to do to fix their design. They sell a lot of these units and it is only a matter of time before a bad accident happens.
So what is left to explain the failure of the overtime circuit than that the thermocouple requires airflow? Especially given that the TC is behind the last bulkhead of the ceramic insulator, I think this is a likely cause. Do you plan to test the TC in situ?
curious if the magnet in the holder interfered with the hall effect sensor. David did mention that it was intermittent so maybe hand piece not locating correctly in the holder
Probably not. The magnet in the holder is a constant magnetic field, the hall effect sensor picks up a changing magnetic field. The constant offset shouldn't harm anything.
Should have tested the hall sensor to see if that was the fail point.
I might have to change the fan in mine to avoid a similar failure even though it is a later model it won't hurt to check.
Intrested in the PID szoftwere insaide inthe chip what does when the fan fails?
I have one of these. I think what happened is that the reed switch didn't initiate the shutdown sequence. In which, the fan stays on until it is cooled down to 100C. it was probably just doing it's thing as normal, not knowing it was supposed to shut down. And David, hearing the fan stop didn't think anything of it, and thought it cooled down enough, and it just kept heating up because it didn't know it was supposed to be off. With the fan going, it cools the entire heating coil, which makes the circuit pump a lot of electrons into it. Without the fan going, it no doubt spiked in temperature very quick.
I'm thinking the fan failed, this caused the heat to rise on the reed switch (their normal operating range is -40 to 200 C), which reduces the magnetic force on the contact arms so it opens, which causes the heating element to come on, which adds more heat. Secondary vector is the heat reduced the strength of the magnet in the holder. And if the reed switch wasn't right on the magnet...
Needs a physical breaker for the element power if the fan is not running when temp is above 100C
i'd replace it anyway, even if it was just a hand unit failure. most of the triacs in these aren't too expensive, so it just makes sense to make sure its going to be okay. with a new handheld bit, it should be right as rain.
Make sure to only download original DaveCad™ software from the vendor website. You can check the authenticity of your product by examining the logo, it should have a letter D with a small face drawn inside of it.
*hehe* Hardware guys are always blaming the software ;)
I don't think it's a SW bug. The SW knows temperature of the air going out but it don't know about air flow, presure or fan speed. And the air don't conducts the heat very well. The SW thinks "OK, it have 200 degrees C, user wants 350 so I put it to the full power to heat up". No way to detect somethink is wrong.
It is definitely HW bug - missing thermal fuse as a last safety components in case of the failure (how much it costs in mass production?), missing feedback from the fan (as used on PC CPU fans), use HAL sensor above specified voltage.
Look at the datasheet, the chip is rated for maximum 16v input power, but it has a capacitor between the positive pin and the positive wire
Hello my hot air gun failed a few years ago similar with what David story was and it turn out to be the optocoupler (it failed as a short)
I don't understand why they didn't use a bimetal thermal switch to cut off the power when heater get overheated like they do in hair dryers!?
At which temperature? In normal use they get pretty hot to get the airflow at 500 degrees even with an environment of less then 10 degrees C. Glowing-hot I guess on the element, actually you see it glowing quite clear when they are in normal use.
A hairdryer is just getting 'warm' compared to this.
If you had one, where to install? Maybe at 2000 degrees C, close to the core but in which direction? Before it reacts when it is on the bottom of the heater, much plastic will have been melted already, probably shorting out the contacts or making a connection with the mains to the metal (death trap for electrocution) or you have to get a real expensive one.
And that will be the main reason... heating handle inclusive transport over the whole world is about 5 -10 Euro's -not much room for expensive safety-things...
Can ya test the coils? I watched till the end to see if the coils were actually bad, or a transient took out the hall effect chip. Wonder if the filtering circuitry that was left out was responsible for filtering out any reverse transients from the coils somehow.
So, does this mean the driver failed, but the motor is fine? I know you hooked it up the power supply, but if you hooked up the motor bypassing the driver would it work? Curious, not sure how these work.
You need the driver, it alternates the drive to the coils so it can spin.
@@EEVblog Gotcha. Interesting. Thx for getting back :)
The coils measure ok BTW.
I have a version of this. The iron and rework station actually work quite well.
But I had to fix things before use (like they fused the ground instead of mains) and I installed a quality mains switch from Mouser.
Still, I never leave it plugged in, because I don't trust it 😆
YT had a video replay from a security PVR in someones house showing one of these cheap tools catching the bench on fire. I tried searching for it but couldn't find it... could someone post the title, if they've seen it? The owner just made it to put-out the fire.
Airflow. I have the smd rework from sparkfun which features a diaphram air pump with adjustable flow. Turned down the flow for a minute with the temp still hot, which was already hot for what I was doing, and found the plastic which was in direct contact with the steel had melted and the tip sagging. Haven't let it do this since and it has not gotten worse. I'm sure the airflow provides a thermal barrier between the element and the steel encasing it.
Was it the windings or the Hal effect that failed 🤔
It wasn't the windings, they test fine.
Thanks for the reply.
Anyone know why the first thing checked was not the thermocouple and its wiring back to the processor? If the thermocouple actually failed first and it thought it was cold, would that not have shut the fan off? I know the fan is dead now but i would imagine a vast proportion of the heat generated after the initial fault happened would have exhausted out of the fan side as it is the pass of least resistance as it has bigger holes than the nozzle.
Absolutely love this channel. I've learned so damn much from it. Thanks Dave and David!
mine stop working something shorted, i determined it was my triac but it still won’t work after replacing it, what could be the problem? moc3041??
It is likely that without the resistors and capacitors installed as specified in the data sheet, transient voltage spikes hit the driver chip and popped it.
Keep the videos coming love it
That part on fan may be not capacitor actually is fuse or resistor
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.
Yes, that's it, the difference between set and is temperatures is without airflow big enough so the set temperature will never be reached, the heating element heats from it's center when there is no airflow, clearly visible by the glowing on the metal pipe, so the difference is huge.
QUESTION ! ! ! The bearing in the center of the motor at the end, was that "wallered" out by wear or did it get warp by the teardown? Worn bearing in motor cause it to hang up on something prevent it from turning? My guess actual cause was motor but it failed mechanically not electrically. Set it down but instead of sense it off it actually locked the motor. Sorry I know bad wording.
My guess is that the fan failed and the radiant heat was too much for the plastic.
Dave, if I am not mistaken you have a similar rework station : disconnect the fan and let it sit for 30 mins ;)
The visible damage is a result of the failure. It seems that you have not yet found the "why" pointing to the root cause. Several more "why" cycles are probably needed...
He mentions it right at the beginning but is obviously too smart to realise that without airflow the gap between set and is temperature id high enough so the set temperature can never be reached, he just say the thermocouple is close enough and dismiss this possibility, because also too much engineer to know the heating element is heating from it's center, right there where the metal pipe begins to glow.
I have some Stagelighting-Dimmerpacks that utilize the BTA16 and I must say everytime a Dimmerchannel blew up on me it resulted in the Triac staying on, dead short leaving the lights at full intensity. It’s an easy fix though by simply changing the damn thing but still every single one of the countless times it has happened failed in its on-state
I would love to see how to calculate resistors for Triac-s that are controlled with opto-triac
2 simple modifications could have prevented the meltdown.
1, A thermal fuse in the heating element.
2, and RPM sensor on the motor itself. If the motor doesn't run, the heater doesn't come on, or turns off.
I would also recommend a warning buzzer, To indicate a possible dangerous failure.
Splicing in a thermal fuse would be the easiest way to make the device a bit safer, but thermal fuses are notoriously unreliable. Considering the high temperature it normally operates at a thermal fuse would only cut power after it's already on fire. The "annoying" problem is thermal fuses can gradually fail when they operate slightly below their temperature limit. After a couple hundred hours it may just decide to cut power even if nothing was actually overheating.
Fans can be manufactured with a locked rotor sensor (instead of RPM). This type is frequently used in DLP projectors with HID bulbs, because they could burst into flames if a fan stopped working. For a device that doesn't monitor RPMs this is the easy way to add safety logic to cut power when a fan dies.
If anything, I'm impressed by how good the WEP station is at such a low price. I'll probably buy one in the future and modify it.
Probably the fan, but could the heat coil get shorted to the metal shield and find the way to a closed circuit, maybe also fry the fan?
New apartment had marginally higher supply voltage and it was enough to break IC in fan?
What ic.....
@@joeds3775 Motor driver
Triacs don't work for dimming line voltage led lights generally. I had to get a new dimmer for mine.
Maybe it comes with a countdown algorithm. If the gate ic failed would that be the same as 100% power on?
For this ic distance to the rotor magnet is critical
i recently decided to buy a "my first" rework station and glad i decided against this one. i noticed about 5 different "brands" with this same form factor and thought twice about it.
just measure the coil resistance of the fan to determine whether the coil is internally broken or blown.
it's up to 16V ?
Best video for ages, ta Dave
its not uncommon in 3D printers to have the thermister fail open and the MCU attempt to heat the heater back up and cause thermal runaway
thats why under temp protection is so important
On a 3d printer with the proper firmware, the printer will refuse to heat if it can't sense the temperature, if the temperature is too high or too low.
unfortunately this feature tends to be disabled to prevent false triggers
another even lesser used feature is the hotend not heating up when it should be to indicate a thermistor or heater cartridge that has fallen off
all fairly simple to implement in anything like this
Fan fail - I wonder if the fan wires are cheesy aluminium and one has gone o/c maybe - you could stick 12v directly on the fan board and just check it still doesn't spin up Dave (I noted the comments above about fan chip voltage range also)......But it seems odd that we have two failures happening at the same moment here, so I wonder if something in the power supply has gone intermittent and is knackering multiple things, like fan and triac drive/control loop at the same time ?
the fan is a BLDC driven one!
Edit: Also, check that fuse on that fan! it might've blown in a safe manner.
The F&P double draw dishwashers have those fans which are 24v.
Would have liked to have seen an insulation test done on the small motor
Why? Ffs its an open circuit.
Hi Dave, Could you make a video about using transconductance on a multimeter ? I have an Escort 99 multimeter I bought on eBay is pretty much the same as the keysight U1252. I manual show measuring resistant but doesn't do anything.
Could you believe that there is nothing about it using that feature on multimeters.
You mean Conductance. You have to take the value in nano siemens and invert it on a calculator to give giga ohms.
@@EEVblog hahaha sorry! Ok thanks