Any opinions on the AiXun T3A?

[drksy]

It looks like aixun just released a new station

It's not release yet so I doubt anyone has tried it.

I just came across this amazing project called the AxxSolder https://github.com/AxxAxx/AxxSolder. I wish I had found this sooner, I would have never bought the Aixun. Bom cost is about 60 bucks, could power T245 and T210 from any DC source 9V-24V. Looks really well engineered. Pair this with any switching supply, or even 18650 batteries, and genuine jbc handle and tip, looks like a total winner.

demo here



I'm so tempted to build one.

[c0d3z3r0]

As promised, I played around with my scope again:

- I was able to reproduce that AC measurement on the SMPS output, but what exactly are we measuring there? @drsky


- The heater signal at the GX12-5 connector looks very similar to drsky's waveform:


- This one is measured with the handle in the cradle (only keeping 200°C, short pulses, zoomed in):


- Measuring the heater signal with probe at Q4-B, Q4-GND again led to weird measurements. So I checked again at the STM32 pin and that signal looks mostly fine. I'm surprised that it takes ~250us to reach 0V again, though. Any ideas?

[dreamcat4]

As promised, I played around with my scope again:
Any ideas?

well perhaps you already know what i had left to say (to repeat myself):

replace the (5) electrolytic caps. then retest again after that... just do the simplest and most obvious thing 1st.

because i don't really see much point to complicate the life with much / many other theories.

[edit] but if you do take out those electrolyics, then can take an lcr meter. and measure individually their esr and values and such.

[c0d3z3r0]

I just came across this amazing project called the AxxSolder https://github.com/AxxAxx/AxxSolder. I wish I had found this sooner, I would have never bought the Aixun. Bom cost is about 60 bucks, could power T245 and T210 from any DC source 9V-24V. Looks really well engineered. Pair this with any switching supply, or even 18650 batteries, and genuine jbc handle and tip, looks like a total winner.

Omg, nice one. It completely avoids the common GND problem, while one could easily add earth (probably 1M resistor *required* and I'm not sure if a SMPS with grounded negative would work then... hmm)

[c0d3z3r0]

As promised, I played around with my scope again:
Any ideas?

well perhaps you already know what i had left to say (to repeat myself):

replace the (5) electrolytic caps. then retest again after that... just do the simplest and most obvious thing 1st.

Erm. You have a weird way of citing \o/ If you didn't drop the sentence before "Any ideas?" you would have realized that this waveform does not have anything to do with these caps...

[drksy]

- I was able to reproduce that AC measurement on the SMPS output, but what exactly are we measuring there? @drsky

I believe we are measuring a trash-tier supply that has high output impedance and can't keep up with spiky current demands in the constantly switching load.

Measuring the heater signal with probe at Q4-B, Q4-GND again led to weird measurements.

That could be parasitic capacitance on the pulldown resistor/transistor inside the (not quiet STM32 more like GTM32) microcontroller. I'm not really sure though, but I don't think that affects the mosfet gate? Q4 will not allow current to pass from its collector to emitter during this "weird" period.

replace the (5) electrolytic caps. then retest again after that... just do the simplest and most obvious thing 1st.

I'm gonna second this, except that instead of all the caps, the most important ones to replace are the four output caps, and maybe even simpler to find one big 10mF+ cap from some scrap board.

It completely avoids the common GND problem, while one could easily add earth (probably 1M resistor *required* and I'm not sure if a SMPS with grounded negative would work then... hmm)

How does JBC do it? Do they put 1 meg resistor between tip to earth? Or do they just connect the supply negative to earth?

[AxxAxx]

Well, Hi!

I saw this question about protective earth comming up here and on the youtube DEMO.
At the moment AxxSolder does not have any protective earth and I have been using it "floating" from an isolated power supply or battery pack.
But implementing it is a good point and I will look into this in the next hardware version.

You can see how JBC did it here where johnmx did reverse engineered the JBC CD-2BC: (he attached a PDF of the schematic in his first post) https://www.eevblog.com/forum/testgear/jbc-soldering-station-cd-2bc-complete-schematic-analysis/
They use 0.44 ohm resistance with a fuse between PE and the tip of the cartridge. If the fuse burns there is still a 1M ohm resistance. In the same circuit they are measuring protective earth currents and amplifying the signal which becomes I_LEAK.

I did an "Issue" on github. It will most likely be implemented together with USB features. See https://github.com/AxxAxx/AxxSolder/issues

[c0d3z3r0]

Nice to see you here, AxxAxx . Welcome!

It completely avoids the common GND problem, while one could easily add earth (probably 1M resistor *required* and I'm not sure if a SMPS with grounded negative would work then... hmm)

How does JBC do it? Do they put 1 meg resistor between tip to earth? Or do they just connect the supply negative to earth?

You can see how JBC did it here where johnmx did reverse engineered the JBC CD-2BC: (he attached a PDF of the schematic in his first post) https://www.eevblog.com/forum/testgear/jbc-soldering-station-cd-2bc-complete-schematic-analysis/
They use 0.44 ohm resistance with a fuse between PE and the tip of the cartridge. If the fuse burns there is still a 1M ohm resistance. I

The main difference here is, that JBC uses a toroidal transformer, not a SMPS.

I'm still trying to figure out how a SMPS should be grounded correctly in this use case:
- negative to earth through capacitance (nope, that's only being done for EMI reasons; anyway, the SMPS manufacturer should do that right (hopefully))
- negative to earth (yup, when it's a PELV supply)
- negative floating (well, that would be SELV)

EDIT: Oh well, that's up to the SMPS being used, so the right question is if both PELV/SELV could be used with one of these options:

... in combination with:
- tip to earth
- tip to earth like JBC did (0.44 ohms + fuse + 1 Meg fall-back)
- ...

(How) would different options influence temperature measurement? Because connecting both tip and SMPS GND to earth means pulling -IN_A of the opamp to GND as well... does that hurt, or is it no problem because -IN_A has no reference to GND anyway?

[dreamcat4]

oh btw:

here is another recent alternative different station, in case you want to evaluate and look at other options

[AxxAxx]

Nice to see you here, AxxAxx . Welcome!

Thanks! 

The main difference here is, that JBC uses a toroidal transformer, not a SMPS.

Yes, indeed it gets more complex the more I think about it. Also considering that the grounding should work equally well with floating SMPS's and grounded negative ones and at the same time not influence the temperature reading. Need some more thoughts on this.. Doesn't look like I'm the first to stumble across this issue though. Here is for example a forum thread about the TS100 Grounding issue which should have the same "issue" as mine: https://www.eevblog.com/forum/reviews/ts100-doesn_t-function-properly-when-earthed/

I guess we should lift this discussion out in a separate forum thread and not hi-jack "Any opinions on the AiXun T3A" if people are interesed in the AxxSolder project. 

[c0d3z3r0]

Yes, indeed it gets more complex the more I think about it. Also considering that the grounding should work equally well with floating SMPS's and grounded negative ones and at the same time not influence the temperature reading.

Yes, I think that's the right question. "How can the tip be earthed correctly, allowing all three battery, SELV SMPS, PELV SMPS?" I've updated my post above: https://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg5118429/#msg5118429

I guess we should lift this discussion out in a separate forum thread

Yep, makes sense.

and not hi-jack "Any opinions on the AiXun T3A" if people are interested in the AxxSolder project. 

Oh well, what about creating a pcb that fits into the T3A case? 

[drksy]

Well, Hi!

Speaking of the devil, and he shows up. Good to see you here and fantastic job on the this Axx project so far! This has potential to be a game changer as an open source T245 alternative to the hairy and confusing unisolder. What I like most about what you have so far is the simplicity.

I saw this question about protective earth comming up here and on the youtube DEMO.

That was me asking the question. I think it's really important to sort out the grounding issue so it can work reliability on sensitive/expensive boards.

They use 0.44 ohm resistance with a fuse between PE and the tip of the cartridge. If the fuse burns there is still a 1M ohm resistance.

I think that fuse is there to protect you/the soldering station in case you accidentally tried to solder a live wire. Based on the schematic you shared, The tip should always be shorted to earth (preferably through a fuse). That 1Meg resistor looks like it's sensing leakage currents to earth through the shunt at the bottom of the fuse. I don't really understand the difference between Earth1 and Earth2 though.

(How) would different options influence temperature measurement? Because connecting both tip and SMPS GND to earth means pulling -IN_A of the opamp to GND as well... does that hurt, or is it no problem because -IN_A has no reference to GND anyway?

Marco Reps made a video about this when he did his open source JBC station (https://youtu.be/cYgjcDbSyRE?feature=shared&t=256). Quoting him:

• "The tip is permanently grounded because best practice, the whole controller section must also be referenced to mains earth which is you know very common BUT if also the heater supply voltage was referenced to mains earth, there would inevitably be unwanted currents through the thermocouple. The easiest solution is to use the transformer with two independent output voltages: one is rectified, referenced to mains earth, and regulated it down to the needs of the controller. The other one is exclusively for the heater and its circuit can be controlled with our optically isolated solid-state relay."

He explains it really well in that video. The heater supply and controller supply should be isolated and only interact with optocouplers.

Oh well, what about creating a pcb that fits into the T3A case? 

I don't know about getting it to fit in a T3A case though. If the handle, controller, and power supply in the Buzzxun all suck, I am struggling to see the big value proposition in this fully-glued $100 product. I don't even like the case because the top doesn't open, and it's just a tube which makes it hard to work in. Probably the only good thing here is the cradle (and even that is made of plastic), but this can be bought separately.

I guess we should lift this discussion out in a separate forum thread and not hi-jack "Any opinions on the AiXun T3A" if people are interesed in the AxxSolder project. 

Make one please.

[c0d3z3r0]

(How) would different options influence temperature measurement? Because connecting both tip and SMPS GND to earth means pulling -IN_A of the opamp to GND as well... does that hurt, or is it no problem because -IN_A has no reference to GND anyway?

Marco Reps made a video about this when he did his open source JBC station (https://youtu.be/cYgjcDbSyRE?feature=shared&t=256). Quoting him:

• "The tip is permanently grounded because best practice, the whole controller section must also be referenced to mains earth which is you know very common BUT if also the heater supply voltage was referenced to mains earth, there would inevitably be unwanted currents through the thermocouple. The easiest solution is to use the transformer with two independent output voltages: one is rectified, referenced to mains earth, and regulated it down to the needs of the controller. The other one is exclusively for the heater and its circuit can be controlled with our optically isolated solid-state relay."

He explains it really well in that video. The heater supply and controller supply should be isolated and only interact with optocouplers.

Haven't watched the video yet (will do) but AIUI you don't have reference to earth from the secondary with a SMPS and thus no currents (except a bit leakage) flowing. I might be wrong, though.

EDIT: Ah, well, the problem is not mains earth but the fact that when PE + GND are connected, you get a current from the heaters positive through the TC to the grounded tip (not to mains earth). See the picture I draw in my post above, where one can see that.

Oh well, what about creating a pcb that fits into the T3A case? 

I don't know about getting it to fit in a T3A case though. If the handle, controller, and power supply in the Buzzxun all suck, I am struggling to see the big value proposition in this fully-glued $100 product. I don't even like the case because the top doesn't open, and it's just a tube which makes it hard to work in. Probably the only good thing here is the cradle (and even that is made of plastic), but this can be bought separately.

I was joking It doesn't make any sense to buy a T3A to build a AxxSolder. It might be an option if you already have one. And no it's not "fully" glued and event the display it not a huge deal. I have opened mine around 5 times in the last weeks and it was easy because I just used tiny pieces of double-sided tape to glue the glass back again

[floobydust]

[...] but get rid of the mercury switch?

Mercury in the handle. Mindblowing.

Thank you!

I changed over to mercury switches - the ball shake sensor is cheap plastic and easily melts when soldered, deforming the pin and then they don't work or go flaky. Very difficult to solder without wrecking them.
Glass is much better it also contains the mercury lol.

Another point to make, despite the "200W" claims for the power supply, it is only ever loaded up for many seconds and does not need to be designed for full power 24/7. So we have a "200W" SMPS further cheapened because the duty cycle is ~20% at worst. I see nothing wrong with it sagging a volt or two under load.
But... it's been cheapened twice maybe three times... the heatsinking, electrolytic capacitors etc. are surely under the minimum for reasonable life.

[dreamcat4]

Another point to make, despite the "200W" claims for the power supply, it is only ever loaded up for many seconds and does not need to be designed for full power 24/7. So we have a "200W" SMPS further cheapened because the duty cycle is ~20% at worst. I see nothing wrong with it sagging a volt or two under load.
But... it's been cheapened twice maybe three times... the heatsinking, electrolytic capacitors etc. are surely under the minimum for reasonable life.

Exactly this - and why to replace the chinese electrolytics is so much justified / justifiable. Because they are shunting / dumping the energy so much in those relatively shortened bursts.

the 3 main brands: nichicon, rubycon, panasonic. You will find options on digikey parametric search, with lowest ESR, highest temp (105 or 125), the most rated hours. and so on.

[drksy]

Ah, well, the problem is not mains earth but the fact that when PE + GND are connected, you get a current from the heaters positive through the TC to the grounded tip

Precisely. When using a dc supply, the best setup seems to be
  -connect the tip to earth
  -the thermocouple will then be referenced to earth, so connect the control board supply negative also to earth
  -use a floating and isolated smps for the heater and turn on and off its mosfet with an optocoupler

One can use an off-the-shelf isolated dc-dc converter to get the 24V down to 5V, for example something like PQQ6W-Q24-S5-S (https://www.mouser.com/ProductDetail/CUI-Inc/PQQ6W-Q24-S5-S?qs=zW32dvEIR3sbKuWv4BvdLw%3D%3D) to run the controller board.

we have a "200W" SMPS further cheapened because the duty cycle is ~20% at worst. I see nothing wrong with it sagging a volt or two under load.
But... it's been cheapened twice maybe three times... the heatsinking, electrolytic capacitors etc. are surely under the minimum for reasonable life.

I wouldn't mind it either if I couldn't hear it. The buzzing is seriously annoying. Gets on the nerves really fast. Don't get me wrong. Aixun has a somewhat cute soldering iron here if it could iron out its glaring problems, ironically  Okay, that's too many puns for one sentence. 1. Get rid of buzzing 2. Fix the grouding problem as demonstrated by tony so it doesn't crap out on grounded boards, 3- put the damn heatsinks back on ffs 4- stop gluing stuff and use screws only 5- Add external ESD protection to the pins of the microcontroller that read ADC values 6 - Add a protection diode parallel to the heater 7 - Improve the PWM frequency and timing to not overload the supply and/or send useless pulses to the tip 8- stop using Aluminium in the handle and improve the construction and 9 - Use the same connector that JBC uses for the handle instead of the ancient and obscure gx12-5 and I think Aixun can be a likable product. The screen looks nice at least.

Something else to note: genuine JBC cartridges seem to have a different pinout than the ones Aixuns use. In the genuine T245 handle, green is earth, blue is heater, and red is common. Heater current starts in the middle pin of the cartridge and returns to the small pin in the end of it. In the Aixun T3A (and also probably T3B), heater current starts in the middle of the cartridge and returns to the outer shell. So much for the handle being compatible with genuine tips. If you were to put a genuine JBC tip in the Aixun handle, 8A of current will be flowing in the thermocouple. Yikes!

[AxxAxx]

Ah, well, the problem is not mains earth but the fact that when PE + GND are connected, you get a current from the heaters positive through the TC to the grounded tip

Precisely. When using a dc supply, the best setup seems to be
  -connect the tip to earth
  -the thermocouple will then be referenced to earth, so connect the control board supply negative also to earth
  -use a floating and isolated smps for the heater and turn on and off its mosfet with an optocoupler

One can use an off-the-shelf isolated dc-dc converter to get the 24V down to 5V, for example something like PQQ6W-Q24-S5-S (https://www.mouser.com/ProductDetail/CUI-Inc/PQQ6W-Q24-S5-S?qs=zW32dvEIR3sbKuWv4BvdLw%3D%3D) to run the controller board.

I like this reasoning. Ground the tip (GREEN) would be the only reasonable, and then handle the measurement issues with a isolated supply to 5V.

[AxxAxx]

I guess we should lift this discussion out in a separate forum thread and not hi-jack "Any opinions on the AiXun T3A" if people are interesed in the AxxSolder project. 

Make one please.

Created a thread about AxxSolder here: https://www.eevblog.com/forum/projects/axxsolder-jbc-soldering-controller/msg5120772/#msg5120772

Next version of the PCB will probably introduce a micro USB as the STM32 can be flashed directly from USB, in that way a SWD programmer is not needed for simple firmware updates.
After that I'll look into making a version focusing on the tip-grounding. Make a physical board and test a few different scenarios.

[c0d3z3r0]

If you were to put a genuine JBC tip in the Aixun handle, 8A of current will be flowing in the thermocouple. Yikes!

That doesn't hurt the tc at all, it's designed for this. T120 only have that way because one connector is missing. Somewhere I read that even JBC does it on some stations.

EDIT: Sorry, I was wrong. C210 has three connectors as well.

[drksy]

I don't like how there is conflicting information about what the pinout of the C245 cartridge is.

It's either this:



based on:
https://www.eevblog.com/forum/projects/jbc-handle-cartridge-data/
http://dangerousprototypes.com/forum/index.php?topic=7218.4545
https://www.eevblog.com/forum/testgear/jbc-soldering-station-cd-2bc-complete-schematic-analysis/
Marco Reps project

Or this:



based on
https://www.eevblog.com/forum/projects/yet-another-controller-for-jbc-t210t245/msg3077826/#msg3077826
https://www.eevblog.com/forum/chat/jbc-tip-cartridge-pinout-and-power/
http://adgd.ru/2021/01/04/jbc-soldering-cartridges-pinouts/
Aixun and other clone tips pinout


Which one is it? One of these is wrong and misleading. Even if the thermocouple doesn't get damaged by it, I would still rather only use the thermocouple for what it was designed to be, not a second heater.

[AxxAxx]

Which one is it? One of these is wrong and misleading. Even if the thermocouple doesn't get damaged by it, I would still rather only use the thermocouple for what it was designed to be, not a second heater.

forget below example, it only tells half of the truth, you can see my cross sections here instead: https://www.eevblog.com/forum/projects/axxsolder-jbc-soldering-controller/msg5124267/#msg5124267

I can do a simple measurement to rule out one of them: 

If I heat the tip with hot air and measure temperature (by using a thermocouple amplifier) between your GREEN (most left connection point) as + and RED (most right connection point) as - I get a resonable temperature reading (Sure it's probably not correct as we don't know what exact thermocouple it is but does not matter for now).

For C245 Cartridge:
If I in the same measurement make a short between BLUE (middle connection point) and RED (most right connection point) I do not get any difference in my reading.
That would indicate that C245 cartridges are connected as your top image.

For C210 Cartridge:
If I in the same measurement make a short between BLUE (middle connection point) and RED (most right connection point) I do get a difference in temperature and my thermocouple amplifier gives me the cold junction temperature, aka 0 mV measured.
That would indicate that C210 cartridges are connected as your bottom image.

This does however not tell the whole picture, I believe I have seen a third suggestion with the heter element between red and blue, and blue and green simply connected.

I have a couple of broken cartridges from the early development of AxxSolder. Ill try to see if I can do a destructive test on the two types I have.

[c0d3z3r0]

I don't like how there is conflicting information about what the pinout of the C245 cartridge is.
...
Which one is it? One of these is wrong and misleading.

While both would work, the second one is "wrong" (heating current through thermocouple).

Take a look at this cut T245. One can see that the middle connector is the heater which is connected to the center pin.
The thermocouple is formed by the center pin and the outer shell. However, you *could* measure the TC also through the heater spiral. It just doesn't make sense to do that, except you wanted to avoid three connections and just use two.


(Source: https://www.eevblog.com/forum/testgear/jbc-soldering-station-cd-2bc-complete-schematic-analysis/msg2955632/#msg2955632)

Even if the thermocouple doesn't get damaged by it, I would still rather only use the thermocouple for what it was designed to be, not a second heater.

Well, if JBC really uses both ways in different stations, I would say it's desined for both ways. A thermocouple is "just" two metals. (By the way, even the heater + center connector form a thermocouple! Check out the measurements done on the site linked below.) Why should they care for current? I'd rather use the "right" way as well, though :-) Oh well, I just saw that C105 only has two connectors, so they are "heating through the TC" there.

@AxxAxx don't waste your time on C245, see above, but cutting C210 like this would be nice!
Someone already did the measurements. http://adgd.ru/2021/01/04/jbc-soldering-cartridges-pinouts/

[AxxAxx]

@AxxAxx don't waste your time on C245, see above, but cutting C210 like this would be nice!
Someone already did the measurements. http://adgd.ru/2021/01/04/jbc-soldering-cartridges-pinouts/

I'm afraid you were too late  , did the cross sections. I posted them under the AxxSolder thread:
https://www.eevblog.com/forum/projects/axxsolder-jbc-soldering-controller/msg5124267/#msg5124267
I think they clear out any questions about C210 and C245 connections.

[c0d3z3r0]

Awesome job, thanks! So, we have the same situation with C150 and C210 - both "heat" through the TC 

[Dracarris]

I have a smiliar, related problem: Bought original JBC tips, but the standby/cooldown when put in stand feature does not work with them. They simply always stay on. Any clue what might be the problem here? Tip is a C245-160E.