Any opinions on the AiXun T3A?

[dreamcat4]

Yes for the opening of these handles - it can be done non-destructively, with some care taken. And perhaps you can see inside what few is in there to go wrong. (If not a poor ground pin contact, but in general tolerances between the rings and the contacts can be less well fitting to make some clean and strong connection).

When the cartridge was connected mid-air, there was no noise

Could you please try to clarify what you are actually saying here?

Are you saying by "cartridge mid air" that you put clips onto a bare T245 cartrigage (not in any handle whatsoever). And then ran yourself custom wires to the base unit, to test the cartidge alon outside of the handle?

Or are you saying that you took a C245 cartridge in 1 hand, and then the Aixun T245 handle in the other hand, and plugged it in while the handle was removed from the stand, that then it buzzed?

but when I used the handle, the handle was buzzing.

Ok. So again, I am not fully clear. Are you saying that "handle is cradle", that when you leave the handle into the cradle stand. That then it buzzes? Because this could be that when the ground jacket of the cartridge is inserted into the stand. That it then has a poor electrical connectivity through the metal stand itself. That then is supposed to go through that banana wire, which is a return path back to the station's sense pin (stand detect pin).

This could then be like something to give a partial circuit, for example if not plugged into. Or if through the MCU isn't clear path to ground.

I am scratching my head here. But when I measure this stand detect pin on my PCB, it's not connected to ground, it's like mega ohms (or not connected to GND path). However you can see on the PCB that they used a green and yellow ground wire to run as a seperate cable to the back of the station, the 4mm banana jack to the stand detect port. That has it's own dedicated wire.

So if you re-assembled your station back together, and mistook this ground marked wire for ground (that it is not actually). Then perhaps some mis-wiring or something can be possible by error? But then the stand detect function cannot work, that the heater cannot heat up. And it seems like an easy to spot mistake. (To eliminate at least).

Sorry if that line of enquiry is redundant, or unclear. But we do at least know that the stand detect (of the stand itself) can be a bit dodgy sometimes. Within the mechanical assembly of the stand, for the way it is constructed.

I forgot now what was some exact discussions about that. But some mod around the hinge nut or some things like that. During reassembly. That the connection fits against.

[dreamcat4]

Me neither. Since both the SMPS and handle are buzzing I really think it's the pwm swichting of the controller...
...
Oh well, it depends very much on the temperature set (how much it needs to heat). Set it to 380 or 400 degrees and you'll hear that buzzing each 1-2 seconds.

This c0d3z3r0 makes more sense probably to explain buzzings. That the PWM is not clean itself. But either double PWM, or that the switching mosfet is kindda failed, damaged or otherwise out of spec? For example, if the mosfet is replaced to a perfect mosfet. Then can the buzzing be eliminated?

In other words, does the ambient conditions affect / impart noise onto the sensitive mosfet gate? (To then mess up the switching).

[c0d3z3r0]

Yes for the opening of these handles - it can be done non-destructively, with some care taken. And perhaps you can see inside what few is in there to go wrong. (If not a poor ground pin contact, but in general tolerances between the rings and the contacts can be less well fitting to make some clean and strong connection).

When the cartridge was connected mid-air, there was no noise

Could you please try to clarify what you are actually saying here?

Are you saying by "cartridge mid air" that you put clips onto a bare T245 cartrigage (not in any handle whatsoever). And then ran yourself custom wires to the base unit, to test the cartidge alon outside of the handle?

Or are you saying that you took a C245 cartridge in 1 hand, and then the Aixun T245 handle in the other hand, and plugged it in while the handle was removed from the stand, that then it buzzed?

but when I used the handle, the handle was buzzing.

Ok. So again, I am not fully clear. Are you saying that "handle is cradle", that when you leave the handle into the cradle stand. That then it buzzes?

I think what he tried to say is: the handle is only buzzing when it's being used to solder (when it's cooled down and needs to heat) but it doesn't when it's just turned on but only cooled down by the air surrounding it.

Because this could be that when the ground jacket of the cartridge is inserted into the stand. That it then has a poor electrical connectivity through the metal stand itself. That then is supposed to go through that banana wire, which is a return path back to the station's sense pin (stand detect pin).

This could then be like something to give a partial circuit, for example if not plugged into. Or if through the MCU isn't clear path to ground.

I am scratching my head here. But when I measure this stand detect pin on my PCB, it's not connected to ground, it's like mega ohms (or not connected to GND path). However you can see on the PCB that they used a green and yellow ground wire to run as a seperate cable to the back of the station, the 4mm banana jack to the stand detect port. That has it's own dedicated wire.

No, the heater current won't go that path. The stand detect cable is connected to a pulled-up GPIO, not GND. GND is on the metal ring, so the GPIO detects that.

So if you re-assembled your station back together, and mistook this ground marked wire for ground (that it is not actually). Then perhaps some mis-wiring or something can be possible by error? But then the stand detect function cannot work, that the heater cannot heat up. And it seems like an easy to spot mistake. (To eliminate at least).

That would mean everyone with that buzzing noise did the same mistake? I'd call this very unlikely

[c0d3z3r0]

Me neither. Since both the SMPS and handle are buzzing I really think it's the pwm swichting of the controller...
...
Oh well, it depends very much on the temperature set (how much it needs to heat). Set it to 380 or 400 degrees and you'll hear that buzzing each 1-2 seconds.

This c0d3z3r0 makes more sense probably to explain buzzings. That the PWM is not clean itself. But either double PWM, or that the switching mosfet is kindda failed, damaged or otherwise out of spec? For example, if the mosfet is replaced to a perfect mosfet. Then can the buzzing be eliminated?

In other words, does the ambient conditions affect / impart noise onto the sensitive mosfet gate? (To then mess up the switching).

Yeah, maybe the MOSFETs differ greatly in quality.

I just had the idea I could set up very simply circuit with Arduino, MOSFET, tip and do some experiments with PWM and see if I can reproduce this behaviour with different timings/duty cycles/whatever... Maybe later..

[dreamcat4]

ok c0d3z3r0 so my theories about grounding issue are largely eliminated. That what you say is to focus at the switching mosfet. Or to the input of the mosfet gate, and how is that signal. And this is basically FET, right? So if you attach a scope probe to the gate line of the mosfet. Will that then affect the signal?

Or (for example if you don't have any oscilloscope) just, you know somehow "safely" to interfere a bit with the gate line. To see if buzzing can stop. Whether by adding some passive to around there or just touching it somehow. *but not to damage the mosfet gate.

[T3sl4co1l]

With this cap installed, suddenly I witnessed the weird bug that Tony shared not too long ago. The screen would turn off, complaining about "no tool installed" and then quickly coming back alive a second later showing a readout of the temperature, and then go off again half a second after. This is getting more and more confusing as I go down this rabbit hole. Why would this happen?

Put a good 10R or so in series with the cap. You've most likely made a VHF/UHF oscillator.

Tim

[drksy]

When the cartridge was connected mid-air, there was no noise

Could you please try to clarify what you are actually saying here?

Are you saying by "cartridge mid air" that you put clips onto a bare T245 cartrigage (not in any handle whatsoever). And then ran yourself custom wires to the base unit, to test the cartidge alon outside of the handle?

Yes, It's the second image in this post: https://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg5085100/#msg5085100. Nothing was buzzing in this setup. But when I introduced the handle later on, leaving everything the same, the handle was buzzing.

Are you saying that "handle is cradle", that when you leave the handle into the cradle stand.

The handle was just sitting on the table.

I just had the idea I could set up very simply circuit with Arduino, MOSFET, tip and do some experiments with PWM and see if I can reproduce this behaviour with different timings/duty cycles/whatever... Maybe later..

This would be a really useful bit of data. Perhaps it's just a bad handle. Or a bad mosfet, or both.

Put a good 10R or so in series with the cap. You've most likely made a VHF/UHF oscillator.

Well, I gave your LC filter a try tonight. It wasn't quite 11mH, but it looked pretty beefy (sadly no LCR around to measure it). When I assembled the filter as you suggested on Electronics SE, again the Aixun started bugging out saying no tool detected or something like that, and it kept going in and out of consciousness. This same exact thing happened when I installed the cap I showed last time.

Then I thought, what would happen if I place the filter on the input of the mosfet, in other words, right after the bench supply. The buzzing didn't improve at all. Then I looked across and magic smoke was escaping from the mosfet. And the handle looked like this:



Oops! Bad idea lol. It looks like the tip was boiling. Thankfully though, the tip survived the encounter, and after some cleaning, all is well. Rest in peace though little fellow



With that, the Aixun had to undergo some surgery to use the n-channel mosfet instead as I showed before. It will have to remain this way until the buzzing problem is resolved and/or I buy a new mosfet (with preferebly lower on resistance).



Let's just say I'm not going back to the LC idea. But it was interesting to see that this LC filter also threw off the thermocouple readouts, which I have no idea why. Next, I'll try to put a 10Ohm in series with the 47n as you suggest, but I have a hunch that would cause the same "no tool detected" intermittent error.

I really wish I had another trustworthy handle to test. Maybe it is better to just take the L and buy the genuine handle from JBC.

[dreamcat4]

Let me just say: a faulty chinese manufactured handle is entirely possible. They are not made quite the same as official JBC ones. And if there becomes a short in the handle, or the cable. Due to an issue internal (that was not checked / dissassembled). Then it can indeed cause the mosfet to explode. In fact the same thing happened to me with an older T12 handle from aliexpress, when paired with a KSGER T12 control board. So if it can happen to me it can happen to you. And also Florian (of Voltlog youtube). He had an issue with this style T245 handle himself, that came with different chinese brand station (and he posted a video to explain what to look for in defective T245 handle). So that is another one to look at.

Anyhow, the other reason for why mosfet can be stuck to on position is the gate input to control the mosfet. So think about it being basically very sensitive charge device. This can be en entry point for damages, or perhaps oscillating. Consider also a busted GPIO pin on the MCU that is then floating. This is another possible.

Replace mosfet, MCU, and handle and all should be fine. However to say is easy would be better to check with scope the mosfet gate. After replacing mosfet entirely. Which you have already done now.

But you must also check handle is not faulty device. So this goes back to prior quesitons / comment. That you tested C245 cartridge bare (with direct wires) outside of handle. And this question you already answered as: no this is fine.

So repeat bare cartridge test, with new mosfet. And individual wires. And you have eliminated handle. If not buzzing then handle is faulty. And must be examined / destroyed / replaced further.

[c0d3z3r0]

Well, what about keeping the handle out of the equation? I mean directly connecting the tip with clamps or soldering the wires to the tip. Does it make a difference? If yes, it could be a) a faulty handle or b) simply the fact that there is no 100% solid connection.

However, I doubt that the original handle is that different. Anybody want to open their genuine handle and see what's inside? 


Btw. can you please test if setting to 380° does make a difference for you as well? (as I suggested in one of my earlier posts)

[dreamcat4]

There are quality control differences between handles, and he already said that without handle not buzzing... so while handle fault is relatively rare, those data all suggests handle issue. If not faulty then damaged seperator rings between the 3 layers of the cartridge, or pushing in the cartridge "too far" so that it goes too deep and then crosses between the contacts. Things like this.

There is also actual tolerance differences between the cartridges itself (genuine or aixun / other chinese ones). So not just tolerance difference within the handle. Could be either or both. But this is all based on speculating until handle is gets checked out properly. Which is highly recommended at this point to focus there. On that part.

... and if not handle then check wiring or cabling to the handle. For any other possible issues.

[T3sl4co1l]

Let me guess, you put the inductor on the wrong side.

Tim

[c0d3z3r0]

and he already said that without handle not buzzing...

Could you please point me to where you read this - maybe I'm just not seeing it.

What I read here (https://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg5076199/#msg5076199):
- no buzzing of the tip when connected directly without handle - ok, so the handle might buzz because of the same reason it buzzes when touching ring and connector
- the control board still buzzes

So, even if you say the handle buzzing is cause by the handle itself due to bad connection (which might be true indeed), it is *not* the source of the buzzing issue. And even when you solve the handle buzzing, the control board and smps are still buzzing.

[dreamcat4]

yes because my opinion is that a handle issue is more concerns to checkout 1st. and be sure is perfect and all sorted out. then after that to subsequently move on to the other things.

because if you have un identified issue in the handle, then you can still blow up your station. which is not very advisible outcomes.

[floobydust]

AiXun T3A - would not buy until they get the bugs worked out.
The video of firmware V1.34 is absolutely hilarious. It stays loyal to propaganda by displaying a nice proper tip temperature- despite an overshoot past 450°C when it freaks out due to a tip ground fault
AiXun seems to be playing too cheap and not very intelligent in hardware or firmware design. We can figure it out here but after seeing the stupid controller reading "360°C" when it's at 450°C... this is kindergarten-level programming.
edit: issue is discussed in this other thread https://www.eevblog.com/forum/reviews/aixun-t3a-misbehaving-on-grounded-pcbs/


There is no protection at all for -ve back-EMF spikes from cable and heater inductance or ESD.
To T12 clones I add a fast diode like RS1M across the heating element to clamp -ve spikes. I have also seen a small cap across the heater to help with that. Would also add to a T3.
Laptop power MOSFET AO4413 max. V_GS +/-25V and V_DS -30V. With those R6 10k, R11 1k resistors gives drive of 21.8V and T12 clones instead use 2k (or 4k7)/1k for 16V or 20V drive.
The power mosfet is of course run near it's max ratings in keeping with doctrine of maximum efficiency, no waste.

[dreamcat4]

yes indeed, i myself am uncertain (and sceptical) why to upgrade past my v1.26 firmware. to be considering caution for that part.

for the handle itself: it is likely that aixun itself not makes these handles. but instead purchase them from another manufacturer. at least not clear. and neither is the q.c. over time clear for these stations. that they check the handle is good, really they should have some test jig with a dummy cartridge probe contacts. and the physical fit / feel that it cannot be pushed too far inside (due to poor tolerances). and so like this, that the customer does not need to check upon receiving items.

for the aixun branded cartridge, is know those had previously some production issue. that aixun latter on addressed after complains and fixed. so this is an open question (from myself). as to the cartridge.

on esd which aixun didn't do for the stand detect line... we just simply need to add 1 tvs diode bridged to ground on the stand detect input line of controller pcb. however in general the gpios on this chinese gd32 mcus seems less reliable, or poor quality, or more vunerable to esd damages (than a real stm32 with proper specs). so this is chinese mcu silicon clone (copycat) die. that they just can perhaps be less certain matters. but i am baffled why aixun didn't add tvs diode on the newest revised controller pcb. maybe on other completely different products they have. but seems not for these t3a station. so that is a miss, but also easy enough to add yourself as a mod. highly recommended step.

anyhow moving on, i have to say also: the fact that the tip is hard grounded is... indeed not ideal design choice. wouldn't it be better thru a resistor? (for example 1mohm is typical for esd grounding, otherwise some other suited values). what would be good is if then the thermocouple can be working and giving valid readings with that esd resistor in place. not to throw it off.

and reverse current spikes....

is probably worse on higher load, when under more duress? because i have not heavy used my station yet. only for mild / moderate tasks. and that would take to hook up a scope etc. which i have not gotten yet. maybe for future i can see these reverse spike and apply mod. (what was it, inductor or something?)

however maybe this also goes back to whether the cartridge is actually genuine jbc, and not faulty. or at least for the temp overshoot part (if not the grounding had thrown off the thermocouple measurements).

if the station firmware is either being calibrated to expect the clone aixun cartridge, or instead a genuine jbc cartridge. which does affect overshoot as we discussed previous on thread. different tc or whatever it is. or poor thermal conductivity into tc area (or voids in manufacturing). can be an issue that simply does not exist with genuine cartridges.

it's some specific issues to consider, yes. but does the whole station makes trash? well i think after mods is good enough. but not without mods. so yes, aixun should listen, and bring out proper hardware revision to address such issues for future customers. and consider that extra efforts for quality is worthwhile investment. to keep brand reputation. to increase brand reputation and trust. (that now we all know the name aixun). and also because fixing does not increase bom cost hardly very much. when others does the work to find issues, then those revisions are their end of the bargain here. to be together in partnership with community. to not to trash a good thing. and weaker glue onto the glass. and such things.

[c0d3z3r0]

anyhow moving on, i have to say also: the fact that the tip is hard grounded is... indeed not ideal design choice. wouldn't it be better thru a resistor? (for example 1mohm is typical for esd grounding, otherwise some other suited values). what would be good is if then the thermocouple can be working and giving valid readings with that esd resistor in place. not to throw it off.

I have not been able to find a clear answer on that. There are various people saying direct earth is better while others say a 1 Meg resistor is better... Anyway, it's unclear if that resistor would influence tc measurements

[c0d3z3r0]

To T12 clones I add a fast diode like RS1M across the heating element to clamp -ve spikes. I have also seen a small cap across the heater to help with that. Would also add to a T3.
Laptop power MOSFET AO4413 max. V_GS +/-25V and V_DS -30V. With those R6 10k, R11 1k resistors gives drive of 21.8V and T12 clones instead use 2k (or 4k7)/1k for 16V or 20V drive.

Oh wait, T12 uses 16/20 V? Well, T245 use 24V.

This stations uses 16-24V for T12 https://oshwlab.com/wagiminator/y-attiny13-soldering-station-smd

[dreamcat4]

as i replied on other thread, i have tested my aixun t3a (as t245) all the way from 24v down to 15.25v. and it can solder in this whole range. at 15.25v seems some exact cut-off threshold the mcu controller switches off.

perhaps soldering performance is something degraded either when:

a) the voltage get less than about 20v

or

b) the current is limited to 5a (because t3a can go up to 8 or 10a).

or

c) when both limiting current and voltage together are constrained.

what i observed myself was in particular testing for 5a 20v limit (on bench psu). was that it affected the loading and cycling on/off. that it would 'stall'. like an aircraft stalls in the air. then after a short pause pile on the load again. so that is rather instead revealing the bring up algorithm. that expects more power on tap. where it runs out of gas. and then has to recover because it took too big a gulping of food. like the behaviour (btw this was running v1.26 firmware, so i cannot say on other firmwares), but it really just is not that concerning. it merely means that the thing is not really designed for too much power constrained situations. due to the software algorithm. and i did not observe any specific hardware issue when driving it under current and under voltage. it seemed consistent and predictable.

if i would recommend anything specific, would be that 5a is generally too low current limitation for powering this device. that 10a is much more ideal, neverminding the exact voltages. however the usb pd specs, gets you given to you 5a at 20v max. nothing more. and then (for usb-c) the power source is supposed to do an ocp triggered something unspecified above 5a. at least according to specs (as far as i understood everything of the usb pd specs, which is not very much).

[dreamcat4]

anyhow moving on, i have to say also: the fact that the tip is hard grounded is... indeed not ideal design choice. wouldn't it be better thru a resistor? (for example 1mohm is typical for esd grounding, otherwise some other suited values). what would be good is if then the thermocouple can be working and giving valid readings with that esd resistor in place. not to throw it off.

I have not been able to find a clear answer on that. There are various people saying direct earth is better while others say a 1 Meg resistor is better... Anyway, it's unclear if that resistor would influence tc measurements

well after reading the commentary about these matters over on other thread. then they seem to say there some very low resistance (less than 10 ohm, perhaps equal pair 1-2 ohm onto each side). and that there is other more complex circuitry to add around the tc amplifier input to the op amp. and such things then probably are best to experiment by copying solutions from those other brand stations. for example like the weller one (or the jbc one). this seems good approach to add back in from simpler basic aixun t3a circuit. but only those necessary minimum where it matters. not to over-complicate what is otherwise basic design. and to be clear what is the key thing. to become a recommended simplest and safe mod (to achieve the goal).

for example with the esd input protection (to gpio). where several guys here made all sorts of complex circuit. for the sake to protect 1 gpio pin on a dirt cheap chinese mcu that costs only $3 on aliexpress. that you do not even need and cap, just simply 1 single tvs diode onto the 1 gpio line. and you are basically done. (to then spent rest of your time onto a variety of other worthwhile mods, or just be done with all fixes much easier and sooner).

[drksy]

Guys I found it!! It's the handle! Tonight I took apart the handle and bent the contacts as much as I could, so it made super tight contact with the cartridge. Then I turned on the station and I couldn't believe my ears. The handle was absolutely silent!

Here's the instructions and what I did:



It all makes more sense now. The flimsy contact from the handle was adding parasitic inductance and resistance, and I bet that's what was causing the resonance and vibration we saw earlier. I just can't believe this mystery is solved!

The key takeaway for me from all this was that every segment of the high current path, from the positive supply to the mosfet, to the handle, to the tip and back to the supply should be bulletproof. Any flimsy connection in this chain will cause buzzing. Hope this helps folks who owns a buzzing Aixun.

Now time to buy a new p-channel mosfet in SOIC-8 package. Any particular suggestions?

[kikook]

Just done on mine. No tape inside the handle here.
Difficult to open it, need to glue it after the intervention.
No more noise frome the handle. 

[c0d3z3r0]

Nice, but did this also solve the controller board and smps buzzing?

[drksy]

Nice, but did this also solve the controller board and smps buzzing?

I don't know yet. I've removed all the make shift circuit, and now looking to place an order for a couple of Si4401DDY
mosfets. With this one, I'd have to increase R11 to 10K so as to not exceed the maximum 20V Gate-to-source limit. Other than that, it looks like a good, overkill part with pretty low on resistance. When it arrives, I'll be using some heavy gauge wires soldered on and will report back the results.

At this point I'm convinced though the buzzing is very much a mechanical problem, and that when thin wires or inadequate connection is made for the heater current, things just buzz. Remember back when I had an n-channel mosfet, hanging in the air powered by the bench supply? Nothing buzzed then. But when I moved over to Aixun supply it did. The way I had connected my circuit to the Aixun's supply was using the rear port, which also relied on the small cable with black and red wires between smps and control board. I actually think this cable is not adequate for the job. It says on it 22AWG, and the metals in the white female header don't have much of a bite. I'll solder on 16 gauge or thicker wires straight from the output of the smps to the power pin of the control board, and return the current from behind the circular connector back to the supply.

Just done on mine. No tape inside the handle here.
Difficult to open it, need to glue it after the intervention.
No more noise frome the handle. 

Fantastic, glad to hear it.

[chemik]

Hey. I'm new here. Bought my Aixun T3A around 2 months ago, after reading quite a lot, especially on this forum;) everything was absolutely fine with the station, at least until yesterday, when it decided to crash. It seems to me that system just got frozen and every time I try to turn the station on all I get is constant beep and white screen. I tried plugging it to the computer to update software, or smthg, but Aixun app cannot recognize my station. Well, it doesn't even read like anything was plugged. Did anyone had similar problem? Any ideas for hard reset, or something like that?

[mebel]

First you should write to the seller, and try to enforce the warranty repair.
https://www.elektroda.pl/rtvforum/viewtopic.php?p=20656000#20656000