Faulty Plasma Cutters - Follow-Up Video (With Thermal Camera) | Will It Catch Fire???
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- Опубліковано 6 жов 2024
- A Viewer called Julian bought a faulty plasma cutter from eBay which I modified to get working. After a number comments, I thought it would be better if we tested if my thoughts and modification were correct.. or not!
I'm not an expert, but I do enjoy trying to fix things.
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Kaiweets KTI-W02 Thermal Camera:
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Other Equipment:
Main Overhead camera: Sony HDR-CX450 with 3rd party remote and RODE VideoMic Pro
Other cameras: Canon G7X, iPhone 6s, Go Pro Hero Silver 7 (which repaired)
Microscopes: Amscope trinocular (clone) with FHD 48MP Camera V8
& Adonstar AD409 Pro.
Editing Software: DaVinci Resolve
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#electronics #electronicsrepair #repair #Kaiweets #thermalcamera
Plasmargon Plasma cutter repair
Plasmargon E04
Plasmargon E02
Plasmargon E01
Plasmargon E04 Error
*** UPDATE *** Since recording this, a few people suggested increasing the resistance of the resistors I fitted. I added another 2.2K to make a total of around 16.9K in parallel with the NTC sensor.
Everything now works as it should. If the sensor becomes unplugged or goes open circuit it shows error E04, I've had the temperature down to -8C and the unit still operates as it should, the fans still kick in around 30C, and the over temperature protection still works too. So if anyone else has this problem around 17K resistance in parallel with the NTC will fix it.
Thank you to everyone who suggested increasing the resistance slightly. imgur.com/a/39xpsuO
Seems to lend to the correct thermistor should have been a 20k NTC. 👍
@@sivalley Parallel not series...
This change makes the values of a 20k NTC match those from a 10k but only at 23c.
I would be very happy to use this machine without concern. In fact, it's far safer now than when it left the factory. One of the problems with youtube, full of sofa experts!!
This appears to be plasma cutters, not sofa's. Not sure what you are getting on about.
It was a good repair but I'd not be relying on that machine to be safe.
Looks like it was made for a £20 BOM, nothing to do with the repair itself.
@@Look_What_You_Did Simply stated, ARMCHAIR experts. Similar to Monday morning quarterbacks. No practical knowledge, just opinions that are not backed up by experience and education.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Cheers 👍
It's amazing how many people don't know basic circuit analysis, but they're experts in the comments section!
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
You are correct. I mentioned the downside of this in the previous video. One if the reasons why I glued the plug in place so it can't came out. As you say the only issue would be if the NTC somehow failed open circuit. I have a feeling other components in the unit would fail before this judging by the build quality!
@@micronetwork I guarantee that was not designed on purpose with a too cold protection, it was just terrible design oversight that wasn't caught because QC testing is non existent. That's what you get with cheap products.
I love ❤ it when you prove the armchair critic's wrong . Well done mate.
Thanks very much 👍🙂
Thank you for answering peoples questions and your clarification of what you have done. Great fix once again
Thank you 👍
Yet again, keyboard electronic experts proved wrong again. 😂
The optimist in me hopes at least a couple of them learns from this demonstration.
I mean it's not a bad thing to think about things that could be accidentally dodgy. As long as you don't insist if you're not sure.
Lol great comment that will make Mick laugh 😂
I didn't see the comments, but the repair was clearly explained and even demonstrated in the previous video. PTC Vs NTC.
These people walk amongst us, can drive & vote 🤦🏻
@@incandescentwithrage Yes sir. There are many smart people in this world. Just ask them, they'll tell you.
It cracks me up when you get all these UA-cam engineers out there that know more than anyone else does. Google University must be full of these idiots. Not only did you solve the problem with the plasma cutter, you also educated a few self righteous know-it-alls!! Excellent work Mick.
Cheers Ron 👍
I quite agree I saw nothing wrong with modification. I would be more concerned about the electronics designed and made in China connected to 240v
@@paulmiller6277 I think that's how China is going to rule the world. They only make the cheap crap to ship out of their country in the hopes they will either electrocute everyone, or just burn down their towns. lol
Totaly agree. ignore the fools. Know who i would trust.
You absolutely don't need to readdress this because of certain comments. However the fact that you did and explain and demonstrated why and how maybe enables others to understand the circuit a lot better. So you actually taught some that didn't know or understand...now they do... Thumbs Up!
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Thanks Gary 👍
As an electronic engineer nice explanation :) Fair play for revisiting.
Liar.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Thanks 👍I'm no expert but I do try, occasionally I do make mistakes too!
Condensation only occurs when a cold item is moved into a warm environment (IE when I froze the heat sink in a warm room). If the cutter is the same or warmer than the ambient temperature then condensation would not form (think how a de-humidifier works). Also "nothing wrong with it" - I'm sure it's designed to work at a temperature of less than 18C.
@@micronetworkhave you actually watched the previous video?! Pointless comment.
Isn't an expert just somebody that has little cards printed that say they are an expert? I'd rather have you work on any of my electrical equipment than any self proclaimed 'expert' who lacks the attention to detail you have. Thanks for the interesting video again!
Your lack of education does not change the complexities of the world around you.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Thanks 👍
I'd argue using a slightly higher resistance (value) than the shutoff-point would be better since that would allow the machine to still detect when the plug disconnects itself again.
Putting them on the PCB was the least intrusive and easiest to reverse - and so the most sensible way to see how the system functions normally.
(But) I'd have been inclined to put the resistor(s) in parallel on the wires so that the plug disconnecting would still be detected -- avoiding the situation where the thermal protection _becomes_ bypassed if the (mismatched connector) fails again. AND/OR trying to find the exact value of resistor...
Says the expert that shorted out his drill press....!
😂 Good one!
@@peatmoss4415 strictly speaking, the manufacturer shorted out my drill-press when they pushed the grommet through the windings, causing the rotor to chip/collide with them (intermittently).
I just watched it burn, then decided to record the last few sparks before I replaced it so that others could too. Unfortunately it was not nearly as impressive as the first dozen or so times (mostly because the metal was already expended; and/or w/ shipping costs, claiming warranty wasn't worth the trouble).
(edit: Dunno what it says that I am so cavalier about electrical safety, but am concerned about disabling the detection of the thermal protection [actually] failing.)
Indeed, the parallel value resistor should be slightly higher (probably between 16 and 20k) to still have the broken sensor detection working fine, but still allowing cold operation of the machine.
Glueing the sensor in will indeed prevent it from falling out, but it still is not protected from a broken sensor! Judging by the 'quality' parts used in building the machine, the sensor failing open loop (infinite resistance) is not an unexpected event in the future.
With the current bypass resistor value of 14.7k the machine will think it is working fine, and it will also believe its running cool. So it will switch off it's fan and happily melt down even faster (and potentially start a fire too with all the plastics inside it).
This was my thought as well (not claiming to be an expert), I know the plug is now glued in but if it does disconnect (or as someone else said the ntc fails) the control board won't detect it as the bypass is hardwired to the socket side.
I was not confused as others were, but I have taken circuit analysis. You explained it perfectly, and it made perfect sense in the previous video.
Thanks 👍
I always love how these "armchair experts" love to confidently (incorrectly) tell people they're wrong. lol
You did exactly what I would have done. If anything it's probably (very slightly) lowered the high temp threshold.
Good work!
Thanks, yes pretty much spot on 👍
Just when I thought I couldn't like your videos more, you do such a clever demo. 11/10 repair. Thank you for sharing sir!
Thanks 👍 Much appreciated!
With the parallel resistors you just created a basline for the controller to work with, as you have shown, it switches off the active cooling when it's cold enough without the fan running, and still blocks operation if it senses too much heat!
"All good!" as a famous australian drain cleaner would say...
😂👍
But where's the corn?? There's always corn
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Cheers 👍
@@gorak9000 🤣
Absolutely love this. Just what i wanted from the previous video. Dialogue and questions are what education is all about. As long as people are respectful and genuinely engage then it should be encouraged. Thats what makes great content and you make great content.
Thanks 👍and that was reason for the second video. People had questions etc, so hopefully that answers them 👍
Great job.
Thanks!
When I saw the thumbnail of the cutter engulfed in flames I thought” … there’s no way!!!!
That was some excellent graphics work with the “fire”. It did exactly what it was designed to do. Made your fans say”…there’s no way!” and your detractors say”…🎉 see, I told you so!” And made all of us watch the video.
Your UA-cam skills are quickly catching up go all your others.
Thanks for the video, they’re great as ever.
Thank you 👍Yes I was hoping this one would get peoples attention. I hope you spotted the "pinned comment" which is a follow up to follow up video!
The only reason I would have soldered the resistors on the wire side instead of board side is that both units showed tendency towards plug mechanicly displacing themselves from the plug. Putting the parallel resistors near the thermister allows for safe service stop for both plug disconnect and most of wire breakage.
Just discovered your channel today! Please note, my comment is not ment to denergrate your solution. But my years of experience fighting Mr.Murphy's Law says to put fix by thermister! Hopefully, you folks across the pond know of Mr. Murphy!
I like what I have seen of your channel, and you have my subscription!
Hopefully, you can inspire a few youngin's of
Today to become tinkerers and fixers of our throw aways!
Semper Fidelis
Bob
Thanks Bob. There has been a little update since recording this. See pinned comment below the video 👍
Good data! Good video! Very satisfying conclusion!
Thanks! Not sure if you saw the "pinned comment" just under the video as there's a little more of an update since I made it 👍
Good explanation thanks for the info
Thanks 👍🙂
One thing the trolls managed to do was to get you a whole new video out of a well-done repair. Trolls can have a purpose I guess.
Yes indeed 👍😂😂
Thanks for the follow up video and kind words regarding my surgery. Some folks speak too soon but learn quickly when listening closely😉 Great fix of course, well done.
Thanks Terry, and you're welcome 👍
Very good! Thanks.
Thank you too!
Yes , You was right to set it parallel to the NTC , if it's hot the resist falls very low in Ohms , so that parallel resister in the range of KOhms has no effect on the shutdown function
Totally correct! 👍
And ….a healthy dose of theory, coupled with proof of concept experiments, thrown in as a bonus vid !? 😱.It doesn’t get any better than this.🙏🏼
😂😂Cheers 👍
Perfect explanation! I was also curious how your resistors fixed it. Now I understand. Brilliant! ❤
Thanks mate 👍
Thanks, I initially had to think through it, but the key to understanding the fix was the NTC which was key and understanding parallel resistors which you explained very well. Only issue now is if it opens up no one will know but hey cheap free China junk at this point. Good fix!!!
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Cheers 👍
@@micronetwork In the first video the answer was YES, they did not work because it was cold. Good point on the condensation something to consider.
hi I agree with you. finally, someone that understands that you can't measure the temperature of something reflective!
Yep, usually it's a matter of tl;dr (too lazy; didn't read) the manual about emissivity.
Cheers 👍
yes that's right
Cheers 👍
Great explanation and it does make sense! There's no risk in this mod imho, and I believe it's now more fit for purpose than it was from factory!
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Thanks 👍The only downside would be if the NTC failed open circuit somehow, but tbf the rest of the unit would probably blow up before that as it isn't the best build quality.
Well done sir - it’s a shame you had to prove people who don’t understand what you did. Keep up the good work I love your channel
Thank you 👍
Spot on Mick, I’d trust you in anything you say as everything you do is educational and well explained, just shows that college degrees don’t beat experience 😊
Cheers Gary 👍
Thought i was seeing things when i got a notification you uploaded midweek. Wish you would do more than one a week but with your incredible talent im guessing you are kept busy. Thanks for the great content.
Cheers Rory, yes it's sometimes a struggle for me to even do one video a week. The time it takes to diagnose, order parts, and repair is one thing. Then editing, reviewing, editing, until I'm happy with it all takes considerable time! For instance if a video is 50mins long after first edit, I then watch it back, adjust and then it takes over an hour to render, then another 50 mins watching it again. If I do that two or 3 times then there's a full day!
Just a great fix you dont need to explain to others just make your videos. But if you like to explain them no problem. Have a nice day🎉
Thank you 👍
Thankyou for taking the time to test the modified circuit.
No problem, cheers 👍
And yes, negative things are always a problem ;) (ntc vs ptc, npn vs pnp ...)
I did not misunderstand, but it's cool you make it clear for everyone with simple but concrete experiment ^^
Cheers 👍
Great job now you ever confirmed the correct operation so there is no doubt it will perform as intended. Good Video as Always..!!
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Hot & cold doesn't cause condensation it is the amount of water vapor in the air that reacts to these changes that cause it. Usually when it's very cold the air is dryer and less likely to condensate. My question to you is what do you believe will short out if there was any condensation & what area of the plasma cuter would be effected?@@micronetwork
@@alfredocuomo1546 You are right "it is the amount of water vapor in the air that reacts to these changes" Water together with leading contamination will short out high voltage circuits very quickly.
Cheers 👍
@@micronetwork Well I haven't seen enough of that to make a call either way, I just think he proved his theory of operation & there was the distinct possibility they may have changed the thermocoupler negating their own design. Either way the owner still has two operational machines that are relatively safe at least for over heating & will work in the cold.
You’re totally right and explained it well.
Thanks 👍
I'd still put the resistor betveen sensor wires, just to E04 to be able to show loose connector. I'm not convinced by compatiblity/quality of those connectors, even if the are glue together. Nice dignosing and fix although.
Cheers 👍
Hehe my daughter saw me watching the last one and I quite liked the idea of a plasma cutter here and she had me wallet away in a second and admonishing finger waggling and nag muscles set to stun "no father you ARE not having one..." :( She's a bit fed up as her old bedroom is now a very crowded area half full of watches (700+ in the collection O.o) and half full of a workbench with pillar drill, 1930's Portass lathe, gasless mig, 3d printer, a plethora of power tools and boxes of stuff for polishing, cutting oh and a 1960's Italian Aspire engine (Tecumseh knockoff) oh and my large compressor, air tools etc... I have just finished refurbishing a Snap On air impact gun which had the local post office questioning me whether it was a naughty naughty gun not an air tool hehe I made a joke showing it to my postie lady that she wasn't equipped with any nuts I could be taking off with it, made her laugh all day she told me :P I did forget to mention front room is stacked with about 20 games consoles, several feet high many stacks of games for consoles, a 1958 Lambretta Li150 and a 1985 Vespa T5 and all my steam engines including a verra rare 1939 Mamod SC3 all original in its original box and accessories, only made for 3 months before WW2 started Mamod said about 100 were actually made... rare as rocking horse bollo... droppings :D
Nice 👍Sounds a bit like my place (with the old consoles etc). A plasma cutter might be a bit on the heavy side for those watches mind 😂😂😂
Well done and well explained, sir!
Thank you kindly!
To be totally safe you would need to calculate what the junction temperature of the power devices are. And check it th3 the max limit, as a 100 deg C heatsink may be too high.
I would also check the earthing and make sure it conforms to the LVD. If its anything like the K40 laser i brought from a uk supplier it was a death trap.
I feel a lot better if it goes back in a safer state than it did when it arrived.
The resistor in parallel should slightly lower the high temperature threshold (but not by much) so they will probably self destruct as intended and indicated in the destruction manual 😂😂 I know what you mean about dodgy stuff! I recently bought a 4000W power controller to be able to adjust the power of a 3KW heating element. That too was a death trap. It had an unfused plug with thin cable, and a main switch rated at 6A! and a very small heatsink (it's actually the one I used in this video). I put the board in a larger enclosure with a CPU heatsink and fan on the main triac, and proper fuses and thicker cables. It now works as it should.
maybe i misunderstood what you did in the original video, it sounded like you said you added the resistor in parallel and thus the resistance would never go close to zero, which of course is wrong and probably why you got so many comments. anyway, so long as it works you did it right, whatever you said.
Cheers 👍
I never doubted you. Great job.
Thanks 👍
Quality follow-up video and demonstrating it as well.
Cheers mate 👍
Best channel on UA-cam
I wish 😂😂Cheers mate 👍
I think what most people are referring to (at least I hope so), is that you disabled the units ability to detect if the sensor comes unplugged or fails open. This may lead to a dangerous situation where the unit will happily keep trucking along without a working temperature sensor potentially overheating. At the same time, it is also not possible to wire resistors in series as this will cause the temperature set points to become skewed, causing the entire temperature monitoring function to not work at all. The correct fix would be to modify the programming to change the 15Kohm "open circuit" detection to something more sensible, but that will obviously be difficult to do. Or you could use a slightly higher resistance (16-18k or something?), so the unit still detects if the sensor is open circuit (unplugged/failed open).
Yes I agree with pretty much all of that. I did mention on the previous video that the only downside of this would be if the temp sensor failed open circuit or was unplugged hence glueing it into the socket (although there is still a remote chance of it failing open) although there is a highly more probable chance of something else failing in the unit before that happens. The skewing of the curve would be minimal I think as the resistance increases dramatically when the temperature lowers. At 0C it should be around 32K ohms. The Fan switched on at 30C which I think should be around right, and it cut out at 90C (Most caps are rated at 105C).
I think you proved it all first time.!
Thanks 👍🙂
Resistance in paralell is lower, in series they add together. So it will cut out faster (at lower temp) when in paralell. Formula to calculate resistance in paralell would be 1/R(t) = 1/R(1) + 1/R(2). Keep in mind that if the termistor dies (open circuit) you will no longer have over heating protection, so its best to increase the value of the resistor slightly so it will cut out if your thermistor goes open circuit.
Yes I mentioned the open circuit problem in the previous video as a downside to the modification. The only problem is the NTC curve is not linear, and drops off quickly at lower temperatures. At 0C it would be around 32K and 64K at -12C
*Thanks* for the Test.
No problem!
It’s great that it worked well, though it was a shot in the dark. It is right to question this approach as taking a chance is not the way to go and proof testing should always be done afterwards to make sure it works within its intended limits. The people that were happy to use it without it being tested would also be happy for their mechanic to replace their car brakes with random bolts and parts too right?
Yes I should have proved it worked correctly on the 1st video but totally forgot to show that the high temperature cut off would still work. I couldn't see any reason why it wouldn't but as you say it's always good to demonstrate it.
Fun to watch both videos. Nice job.
Cheers 👍
The haters always hate their betters Dude.
Stick it to them..
😂😂😂Cheers 👍I should have really tested it properly on the first video, but I assumed it would work as I thought it would. Guess it's still always better to prove it on camera though.
Thanks for this
You're welcome 👍
Parallel is correct ... but ... you also have to take into account that if you ( for example ) put 2 x 1/4W 10K resistors in parallel, it becomes a 1/2W 5K resistor array.
Very true, although not really an issue on this as it's just being read by a microcontroller.
Perfect explanation as always... brilliant
Cheers 👍
Great job done😊
Cheers 👍
Great explanation mate. Right one. Cheers
Cheers mate 👍
Does not matter. As long as your animals are safe 🙂
Cheers Fred 👍
Excellent. Now all you need (for the failed open scenario) is an Arduino monitoring current into the thermistor or wrap one of the thermistor wires around a reed which is in series with your resistor mod. Both super-easy mods, if only in my head, ho, ho.
Cheers Ralph, a few people suggested using a very slightly lower resistance. I might give that ago and pin a comment on this video if it works 👍
@@BuyitFixit Another thought was to follow the circuit back towards the micro to see if there is a tweakable divider or comparator or something. I suspect that you have already done this and there's probably just a piece of wet string.
The safety trolls are having a freak-out. You have to be careful about feeding the trolls. They're hungry all the time.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
@@micronetworkI think I've heard you say this before.....
9:25 oh don't worry, the only thing you burned down is the people who thought they knew it 😂
Keep it up brother 💪 you know what you are doing :)
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Cheers 👍
I'm sure somebody already said this, but according to Ohms Law parallel resistance is calculated as Rt=1/R+1/R+1/Rn... so in this example at high heat and taking 10 Ohms as the thermal probe value the resulting total resistance would be calculated at 9.96 Ohms. within the range to throw a high temp error. His explanation, while a bit simplistic is sufficient.
Just an update (pinned comment) I've added a 2.2k in series to make a total of just under 17k, as a few people suggested increasing the resistance I used slightly. Now everything works perfectly including including sensor failure detection.
Awesome ! I think it's wise to draw it out like that to fully understand before making a fool of yourself in the comments !
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Cheers Andymouse 👍
Well explained, Mick. I knew you couldn't let the comments go on. I too would have done the same. Thanks for sharing.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Cheers Brian 👍
Nice, i dig the new thermal camera. That will be my next purchase. Especially since i see paranormal channels use them and with interesting results. (Ghosts or bigfoot)
Excellent test results. Perfect proof of concept.
never can get a good picture of bigfoot. bigfoot is born blurry
Cheers 👍
😂😂😂😂
I've owned not one but four and yeah I have absolutely positively fucked-up a few Parkside (Lidl) plasma cutters in my time. These cheap inverter-style plasma cutters and welders are handy for short jobs, but suffer from short duty-cycles and as a result rely heavily upon multiple thermal protections to prevent spectacular meltdowns. Take it from me, they can go tits up quickly with a seriously loud audible notification! 😉
😂😂😂😂Cheers for sharing 👍
@ 5.54.....what can't you hear ? 🤣
Great vid btw
I'm not sure if it's pronounced keerch or kiiirrrchh 😂 Thanks 👍
People with zero knowledge of resistance in series vs parallel connection questioning an experienced person's repair with confidence of PhD in electronics.
😂😂I'm still no expert, and I do get things wrong occasionally 👍
The commenters are incorrect. You are dealing with Facebook experts, not reality in this venue. You did exactly what the mfgr wold have done to sole this issue.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Incredible that after all your skilled repairvideos, you still get these comments 😂
Thanks 👍
Bush Barbie says there are people on this planet that shouldn't be. I know she is right. Keyboard experts are usually wrong and nothing lost if you pay no attention to them. For fun, I look at their channel and they usually don't have any content. As always, comprehensive video and spot on...!
I think the confusions comes from the fact that this only works if higher temperatues *lower* the sensor resistance. It would indeed bypass the security if the sensor resistance would rise with the temperature instead.
@Mobin92 you are so right. By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
Well I have a Jassic MIG welder, and an Eastwood plasma cutter which are both way superior in quality. Both work in freezing conditions with no issue. The Chinese plasma was cutting out at anything below 18C, so "perhaps there was nothing wrong with it" doesn't really 'cut it' IMHO.
Appreciate the follow-up, but really, that extra parallel resistance should have been a bit higher - 22k would have allowed the open-circuit detection to still work if the thermistor failed open circuit or the plug came out again. Using 15k stops the unit detecting open circuit at all.
Correct, but the NTC resistance increases dramatically at lower temperatures. I'm no expert but at 0C the resistance of the NTC would be around 32K ohms and 64K at -12C (not that I'd fancy using it in -12C) 😂😂
@@BuyitFixit Ok, very good point. In that case, I’d have spliced the resistors into the cable and put heat-shrink tubing over them. Those chinese thermistors have a tendency to crack with heat cycling, and of course that plug could come loose again. Preserving the open-circuit detection is pretty important, since without it the unit will keep going until it burns up, and we all know what happens when MOSFETs get too hot - they go short circuit. You’d think that would immediately blow the fuse, but since chinese units tend to come wired with that crappy aluminium-cored copper plated cable, the resistance is too high to blow the 13A fuse and the cabling just goes up in flames.
The wire on these seems fairly decent. Ive encountered that thing aluminium stuff before and more recently on a 4000W speed / power controller that I bought from ebay to control a 3KW water heating element. I ended up pretty much re-building it in a bigger case, with thicker wire and got rid of the 6A! switch it had fitted which would have just melted! I also put a bigger fan cooled heatsink on the triac (the old I removed was one was the one I used in this video) which was far to small for the job.
you made the classic mistake , of putting the heatsink on a yellow brick and not a red engineering brick ,this could have caused a worm hole to open ,causing a tear in the space-time continuum , and the complete destruction of the known universe as we know it .rookie mistake lol :P nice job :)
Damn I'll pay more attention next time 😂😂😂😂Thanks 👍🙂
With that plastic hose inside, run it on argoshield or better. It'll cool it down, like a fridge . Helium could be even better😅 and a good laugh . Does say argon on the cover
😂😂😂👍
If I may be so bold as to suggest it, I think some of the confusion stems from time stamp 34:03 in the original video where you said "resistance can't go below" when I think you meant "resistance can't go above", and the same thing at timestamp 8:25 in the followup video where you again said "drop below that" although in that second instance I think perhaps you were meaning the temperature not the resistance?. Both times when I heard it I said to myself "eh, what?". Didn't comment first time round, couldn't "resist" this time :)
Exactly 🙂
Yes my bad. I'm only human and do make mistakes occasionally 🙂
Yeah, this is what confused me too.
How dare people doubt you! 😂
I'm not always right, and I do make mistakes 👍
My question is, why didnt you out across the plug on the leads side?
These units seem to have an unplugging issue. If the temp sensor lead becomes unplugged, the unit will still work, no? And then, without the sensor being plugged in, the unit could overheat. It you put it on the leads, at the base of the plug, and it became unplugged again, you would know and the safety system would work as designed.
I think its a great fix, but I think not putting it on the wire side, can cause potential danger because it can still operate when overheating.
I could be wrong, but am I? I could be mistaken, but i thought it ran without the leads being connected in other video.
Yes you are correct. It's the reason why I glued the plug into the connector. The only issue is that if the sensor goes faulty (open circuit) then it could overheat and fail. I did say that this was a potential downside, but without reverse engineering the software in the microcontroller I can't see any other way around this.
@@BuyitFixit If the resistor was put on the wire side of the plug, instead of the board side, and the hot glue gets hot enough to soften, then a plug disconnect would throw the sensor disconnected error, and a thermal failure couldn’t occur.
While I think your solution is very smart, I think it could be safer by removing resistor from the board, and then put on the wires instead, it would offer more safety.
Thanks for your work, its gets me thinking!
Not sure if you will get to read this, but still...
The only problem with the units is that the temperature thresholds are unfit for UK climate ( and other countries with cold climate ), that is a dumb thing but they are China stuff so...
Who ever said that the mods should have been in series with the NTC should really read about Ohm's laws and about how an NTC works!
When you did the mod you lowered the overheating threshold because as the NTC heats up it's resistance lowers and that is just what you did, lowered the NTC's resistance ant room temperature, meaning the overheating protection comes at a lower temperature now.
As i said, people should learn basic electronics, like Ohm's laws, and basic components and paralleled and series resistance, and stuff.
You did go slightly wrong on the mods, but not on the configuration ( putting the resistors in parallel with the NTC was the only way to go ), but rather on the values chosen.
You really need to make sure the mcu still reads when the NTC is disconnected, because it can happen and when it does, everything temperature related will be off, and the unit will no doubt fail quite spectacularly!
What needs to be done is lowering the threshold at which the "NTC disconnected" protection comes in, without nullifying it completely. This is done by trial and error way, your mod is fine, just it's value needs adjustment, until you reach a point where that protection still comes in but at a lower temperature threshold ( say 0*C for example ), without compromising the overheating threshold, which must be checked each time a mod value change is done.
The way i see it, i think the mod value should be a larger resistor, you use the same pot in parallel with the NTC ( while the NTC is mounted on that smaller heatsink ), and everything connected to the board, and the unit powered on, you adjust the pot value until you see that the "NTC disconnected" protection comes in at somewhere below 5*C ( i think that would be just fine ), then you check the overheating threshold, making sure it is still ok.
You do not want the overheating protection to come in too soon, you cannot do any work that way, but it should not be so high as the heatsink starts smoking, somewhere between 80 to 100*C should be just fine ( also you should check at what threshold the fans starts ).
I always try to read and reply to all comments. Sometimes I do miss the odd one. I know exactly what you mean and I did think about putting in a higher value resistor. The only problem is that the NTC resistance drops off quite quickly as the temperature lowers. At 0C is is 32K and -12C 64K (approx). It is often below 5C in the UK in winter, so the unit would not function. I did mention the downsides of this mod in the initial video and that if the NTC failed open circut then there was a risk of the unit overheating (reason why I glued the plug in). In reality other components in the unit will probably fail (as we know what the build quality was like). The proper way to fix it would be to reverse engineer the circuit, and perhaps even the software in the microcontroller to set the lower disconnect threshold do something like 64K ohms, but that may not be possible.
@@BuyitFixit first of all thank you for reading and responding to my comm.
Now, about the issue at hand, the mcu doesn't know and doesn't care about resistance values, it can only read voltages with its ADCs, and that is what the NTC does in what probably is a series circuit with another circuit to some DC voltage, which then gets adjusted as the NTC resistance changes, and that proportionality of the voltage to the NTC's resistance is what the mcu sees, and thus changing the software is pointless ( or should i say not needed perhaps ).
What needs adjusting is that voltage proportionality range, meaning you adjust the resistance needed for some temperature range.
You measured ( if i am not mistaken, please correct me if i am ) about 15k of resistance needed in the NTC socket for the "NTC disconnected" protection to kick in, and if you want the unit to work at let say those -12*C you just mentioned, at which you measured 64k from the NTC, then you need another resistor in parallel with that NTC which at -12*C ( 64k ) would give a total resistance of about 15k, that needed resistor is just under 20k, and would dominate in a 3/1 ratio the NTC, so the total resistance would not change as fast as the NTC's resistance does.
For example at 0*C you measured 32k, and with a 19,6k in parallel with it would give just over 12k of total resistance, just 20% of total resistance change, compared to 50% at the NTC.
Not sure of what resistance is needed for the overheating protection to kick in ( if you tested it in the last video and it escaped me, sorry ), but i think it is quite a low value ( probably tens or maybe hundreds of ohms ), so the 19,6k ( a 12k resistor in series with a 7k5 one would do just nice for example ) would have quite an unsignificant influence on the overheating protection point.
All that remains is to check at which point the fans start, just to make sure they do kick in when they are needed ( they could come in a bit sooner, but that's even better, you cannot complain about fan noise in such a device ), that is if the fans are temperature controlled.
Thanks for that. I had been thinking of lowering the resistance slightly as a few people have suggested. I'll report my findings in a pinned comment on this video 👍
I'm guessing if the RTS becomes unplugged again both the high and low cut outs as well as the RTS disconnected error won't be triggered? But then you have glued the plug.
Correct. The only downside would be in the NTC failed open circuit somehow.
08:04
Resistance isn't futile🤣🤣🤣🤣
🖖🖖🖖
😂😂😂😂👍
It only worked because the sensor lowers it's resistance to almost 0 with rising temperature, right?
Yes, although at 30C when the fan kicked in, it should be around 8K ohms.
Had to look twice. Thought you new camera had a milf setting not mlf 😂
😂 That's definitely the proper tool to search for a hot milf.
😂😂😂😂👍
Hi
Loved these videos so much I went out and bought a faulty Plasmargon PLC55.
Very much hoped it would have the same fault.....nope!
This one is completely dead. No lights on main switch or panel, no fan etc.
There is A/C power to the relay.
If I apply 24V to the coil of the relay with the bridge rectifier DC wires disconnected, then I can hear the relay click.
If I do the same thing with the bridge rectifier connected, then the mains RCD gets tripped.
I take it there is a short somewhere, any pointer of where to start looking, please?
Kind regards
Rob
Thanks 👍I'd start by checking the bridge and then the mosfets. Check also the board isn't touching the case anywhere too! Make sure there's no voltage in the capacitors first as they'd give quite a belt I bet.
@BuyitFixit
Hi, thanks very much for the advice. The bridge rectifier seems OK, getting 180V DC out of it if I apply 24V to the relay coil, as long as I disconect the DC out leads from it. If the DC out leads are connected, then the rcd trips.
Will check the other items you mention tomorrow.🙂
Keep the videos coming, please, very clear and informative.👌
Thanks again, Rob
Sounds like they fitted the wrong NTC from factory...
Yes I thought that initially, but most of the temperature curves were similar on the NTCs I looked at.
send this video link to the seller
😂😂😂😂😂😂😂
Does it still sense the sensor being unhooked? That is my fear. It gets unhooked and goes to a base reading and can keep running till it over heats?
No, I explained in the previous video that if the only downside would be if the sensor became unplugged. That is the reason why I glued it in, in the previous video. The only issue is if the NTC failed open circuit "somehow" but the way the unit is built I expect it would fail with other issues before that 😂
5:54 excellent impression of a plasma cutter, or maybe a dolphin...🤣🤣🤣
To be read in the most nerdy whingy voice you can imaging...
"Dear Mick, if that even is your real name, this is a sloppy explanation/demonstration at best. To really real world test your hypothesis you should have spent several days cutting out the pieces for and assembling a trike, or motorcycle of some sort. Only then would your testing have been in any way believable. The manor in which you tested is of little to no value as, for all we know, you could have rigged the results, or used camera trickery..."
🤣🤣🤣🤣🤣🤣
Bloody keyboard warriors, they've probably never even used a soldering iron in anger. Christ on a bike, you couldn't take a p1ss on the internet without some tw4t jumping all over ya, telling you your doing it wrong...
Keep up the excellent work, you're content is brilliant!!! Ignore the detractors.
Not to be confused with how your neighbours would say the tractors, as in "hey up, der go detractors inta field son" 🤣🤣🤣🤣
😂😂😂Cheers mate, and yes it is Mick 👍
Do you consider this to be fixing a design fault or a build fault? Could it have been a tolerance fault with the NTC resistor?
How is the temperature sensor measured? If an AtoD on a processor, the manufacture could have fixed the fault with a corrected software setting, as the error messages indicate a window detection function.
It would have been informative to measure the voltage across the NTC with temperature, as this would have indicated what the processor was measuring. The NTC resistor is likely part of a resistive devider network, with either the NTC resistor or its associate fixed resistor referenced to circuit zero volts. While the fix clearly works, it might be masking the real fault in the A/D circuit. The incorrect connector might indicate that the NTC resistor was from a different component supplier and maybe had a different characteristic.
It is impressive that you managed to locate the problem with so little information, not even a circuit diagram, something you manage to do in other product fixes.
While the fix solved the problem, which maybe all that matters, it might not be the real source of the problem, which could be a design fault, a component tolerance spread problem, a component supply problem, a software setting problem (perhaps in manufacturing alignment) or a build fault with the sensor associate resistor or its power source. It could even be with the A/D voltage reference.
Even with such a poor build quality, it might be unwise to assume such a simple design fault as not accounting for a low temperature operating environment. These units are likely made in volume, so such a design fault would prove very expensive.
I didn't really investigate the circuit too much. It could have went directly to the MCU via a resistive divider. It could be a software problem. I did a follow up video to this one where I tested everything with a thermal camera, and then I made a slight modification again in the pinned comment under the video. The machine now works perfectly including showing the error if the sensor fails open circuit or becomes disconnected 👍
@@BuyitFixit I appreciate that you very successfully found a work around for the fault, but adding components that were not in the original design can only be justified if there was a fundamental design error. Time pressure and the need to make this poorly constructed product work is a very good reason for applying the fix, and you did a lot of work to show it is both safe and practical. But the purist might think that the work around is actually hiding the real fault. I suspect that the problem may have been that the product manufacturer had some problem sourcing the correct NTC resistor, as is evident from it having the wrong connector, however the real fault may be in the A/D circuit and what was fixed was simply a symptom. Diagnosing and fixing cascade faults can be difficult, for example an intermittent faulty PSU may blow associated components. These can be replaced and the unit appears to be working, only to fail again when the source PSU fault reoccurs. This is not a criticism of your work, simply an observation on the nature of fault finding. As a general rule, it is wise to assume that a faulty product was originally designed and built to work. This is reasonable in most cases due to the very high cost to the manufacturer if this is not the case, particularly in high volume, safety critical, or expensive products.
Design faults are more common in products that contain software, and are often labeled as unintended features.
Thanks for that. Yes I think wrong NTC or software but this was the easiest work around I thought. I did have something like this before where someone bought a load of Philips sound bars which all worked for 15 mins the started cutting out due to overheating. This seemed to be a design fault so I modified the circuit to match the amplifier chip manufacturer recommended circuit and it worked fine after that. Video on those is on my channel too if you didn't see that one.
Hi, with this setup with it give the thermistor disconnected error code?
No, I explained the downside to the modification in the previous video. This is one of the reasons why I glued the plug into the socket. The only issue would be if the NTC failed open circuit somehow.
So they're worried about a fire while cutting things with fire or plasma. Got it.
😂😂😂LMFAO very true!
There is one issue left though. Adding the 14K7 disables the missing NTC detection because the uC always sees the 14K7 resistance and not the infinite resistance of a missing NTC.
So if the NTC goes bad no error message (E01 was it?) will be displayed, effectively not detecting a posible overheating and shutdown of the device. Or is there an other overheating cut out in place?
If the NTC fails open loop (disconnected, burnt out, etc) it will indeed still keep operating. It will also believe the heat sink temperature is below the fan cut-in point, thus the fan will stay/turn off and it will overheat even faster until it fails/burns up due to heat damage.
Yes, it was the potential downside that I mentioned in the previous video. The mod I did isn't perfect but without modifying the microcontroller code I can't see any other way around it, and have the unit operate at a temperature lower temperature range. At 0C the NTC would be around 32K ohms, and 64K at -12C.
Hi, if you connected the resistor in paralel on the sensor cable instead on board it would work same but it would also throw an error code when you disconected the probe from the board or am I wrong ?
You are correct, but it would be much more messy to achieve. However, heatshrink tubing hides sins like that rather well… (the better solution is to just use a slightly larger resistance, so that the parallel resistance of the thermistor at 5 °C or so and the additional ‘bodge’ resistor is still low enough to avoid triggering the open-circuit protection while the bodge resistor is still high enough to trigger the error if the plug falls out or the thermistor fails open.
The only issue is that the NTC resistance increases dramatically as the temperature drops. at 0C it's around 32K and -12 is 64K. It might be hard to choose a resistor that would allow it top operate at 0C (which it is often in the UK especially in winter) and keep the open circuit protection.
My worry is that if the temp sensor plug manages to work itself free again, the resistors you've added will make the cutter think the temperature is fine even if it is overheating.
Says another keyboard expert with no channel content...!
The plug has been fixed with hot glue. Geeez, suppose the mighty hand of god came along and swiped the operator into orbit!
Correct. As mentioned elswhere the resistors would be better spliced into the NTC leads. It would at least cover the possibility of the NTC plug falling out. The only issue then is if the NTC fails open there would be no way for the controller to see an over-temp situation. It's a poor design of that cutter. If it was mine, I'd remove the NTC and replace it with a thermal switch and series resistor.
I had thought of a thermal switch but then there are different levels it seems to sense. For instance the fan kicks in at 30C and the overheat kicks in around 90C
@BuyitFixit Yes you are right. Trying to solve a design issue can be problematic. The main requirement in this case is over heating. If the fan keeps going there isn't really a problem other than the noise. But hey. It's a workshop. Noise happens in workshops 😄
Love your content as much as everyone else here. Even though I've been in the industry for 50yrs (retired but still active) you always learn from others techniques.....
Cheers
Pete' New Zealand.
In reply to my previous video comment "Resistance in parallel will not work."
Ohms law is "the total resistance in parallel will always be less than the smallest resistor."
This was based on your wrong answer in the comment section in reply to @nickalexander6773
"The resistors just stop it dropping lower then 15k"
and your wrong comment in the video saying "The minimum it likes is 15K"
ua-cam.com/video/2wt5Y-lyqO0/v-deo.html
Beside you being a great source for entertainment you also provide a great source for learning,
By providing wrong explanation how it works you mislead your viewers, anyhow you seems to understand it fully now🙂
By disconnecting the too cold protection with the resistor, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
I did make a mistake by saying that in the original video. I'm not an expert and I do make mistakes at times. Condensation is unlikely to occur unless the unit is very cold and then being brought into a warm humid environment (but that would be the same for any plasma cutter). I own an Eastwood plasma cutter, and that works in 0C no problem. The original user tried to operate it in a 10C garage, which is should work no problem and not cut out below 18C.
@@BuyitFixit Yes we all make mistakes, that's how we learn 🙂 Other UA-camrs make a correction with text on the video when they say something wrong, seems like a good idea, on the other hand you have had a hot comment section lately and that's good for the algorithm 😂
Yes lol 😂😂
Makes me wonder how many of those people who said you do it wrong or it could start a fire have actually got electrical engbineering certificates or have been college to learn all of that stuff. Perhaps they just have the ability to change a 3 pin plug and hope they dont blow a fuse afterwards.
They haven't got a clue. Couldn't change a plug either.
Thanks 👍
Can't fix stupid. You mentioned quite clearly that your mod affects the bottom end of the temperature curve, not the top end. Nowt wrong with them. Now.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
😂😂😂😂
How embarassing, accusing someone of making a device dangerous and being so utterly wrong! They probably voted for Labour too, lol
😂😂😂😂😂LMFAO 👍
Adding resistors ONLY sets a low temp point and did not affect the high temp point.
By disconnecting the too cold protection, condensation will occur when used in cold environments, and the cutter will short.
Maybe it was nothing wrong with it at all? Can it be that the user have tried to use it in cold environment?
@@micronetwork Did you watch the first video? I think not, as it was triggering a low temp warning at about 18c, and it had to be warmed up with a heat gun for it to work.
Yes, I'm sure it is supposed to work at a blistering cold 18C 😂😂😂