Aixun T3A misbehaving on grounded PCBs

[Icchan]

I made a video on this issue (and more generally to compare the T3A to a more traditional soldering iron). Let me know what you think!

Did you check what happens if you have 1Mohm to the ground like with ESD-mats/ESD-wristbands or if the item is "grounded" through an ESD-mat if that causes the issue as well?

[Icchan]

Try a 1N5819, SS24 or ES1B etc. what you have lying around in the junkbox.

I have bunch of 1N5819's, I'll make sure my unit is affected and if this mod helps. I'd appreciate everyone else affected to also try it and report to the thread.

[tony359]

my software also says 1.0 and I'm not thinking of opening that thing for now for the reasons you mentioned!

[tony359]

I am so disappointed by the T3A.

Today I did a large PCB, 100+ SMD capacitors so I'm using two irons, one being an older, more "traditional" one.

On almost every capacitor on the power rails the T3A displayed the "no tool" issue, temperature skyrocketing and tip discolouring because of the heat. When I did an identical board weeks ago, it only happened once, today it happened on 40% of capacitors. The PCB is not grounded and my pre-heating station is insulated with tape. But the other soldering iron is, obviously, grounded.

I tried downgrading to much older versions but
1. The display is messed up, I suppose the latest FW works with a different version of the display
2. the issue still happens even though with a different behaviour (is it better? who knows).

I cannot recommend such a tool, it's pointless. I am really tempted to break the bank, get a JBC and forget about those issues.

[ndarjo21]

Try mechanic brand. C211

[tony359]

do you have direct experience with it?

[ndarjo21]

Nah, cause you have far more money than me, i hope you can give the testimony. Lol. Sorry for that suggestion. JBC is a way to go fo yoy. Or perhaps metcal is another alternative

[tony359]

I don't mean to be harsh but what is the point in recommending something you don't know?

[ndarjo21]

I wanna buy that. And i dont have enough money to buy it right now. So, i hope someone which have more money will try it to fullfill my desire and curiosity. Thats the truth.

[Zero999]

Wow. I can't believe anyone would design a soldering iron which leaks current to earth and malfunctions, when the tip is grounded!

Are there any other soldering irons which do this? It would be good to know, that way I can avoid buying one.

[hasbihal]

@Tony did you try plugging in a 3.5mm jack for ESD? I just read somewhere else that an old system used to have grounded tips but as soon as plugging in even a blank 3.5mm jack into the ESD jack, the tip was not grounded anymore. Try that

[tony359]

on the T3A?

The T3A has a banana jack at the back, not a 3.5mm jack. I'm not sure I'm following.

I've been thinking of cutting the ground of my traditional solder iron to avoid the issue but I don't think it's a good idea. It could be dangerous for the PCB I reckon?

[run_rabbit]

A new version is up, have you tested it?

https://aixun-updates.github.io/#t3a

[Icchan]

Plot thickens... I believe floobys solution would fix all of this: https://www.youtube.com/shorts/6rK7ACrbukI
Because it all makes sense.

[floobydust]

OMG AiXun T3 tip has enough PWM noise enough to make a speaker buzz?! 
Too cheap china, too cheap on the cable, or maybe they wired the handle wrong.

It would take 1 minute with a scope to figure out this drama.

[ohmware]

what is the name of this pin?

[ohmware]

is this a ground pin or earth pin?

[GnomeZA]

I cannot recommend such a tool, it's pointless. I am really tempted to break the bank, get a JBC and forget about those issues.

So here is my problem with the JBC stations
1. They recent had the debacle with silently dropping features
2. Quality control issues where the DDE has splattered solder over the unit
3. "Chang" capacitors on overpriced JBC unit
4. JBC unit with a through hole capacitor bodged onto a SMD pad with tons of flux still on the board!

What this tells me is that JBC has a serious quality control problem.  And they have NO qualms about sending out bodge or dodgy things to their customers.


I got one of the Aixun T420 stations and it is identical to SDGs station, so he didn't just get a cherry picked review sample.  Some highlights from that unit include:
1. Very good quality toroidal transformer (JBC units are using EI core transformer)
2. PCB and internal build are on point, not a single bodge, not even left over flux you usually see in cheap Chinese parts.  It really is very well made IMO.
3. T115, T210 and T245 from a single station, huge selling point, you absolutely need to spend a fortune to get this with JBC.  The prices are nowhere near comparable.

As such I'm at a point where it feels like the Chinese clone is starting to even one-up JCB in terms of assembly quality.

I also very much share the concerns about the temperature overshoots but Aixun actually seems to make firmware improvements based on these reach outs.
Their latest T420D updates have added "temperature compensation" menus, so I assume they've listened to people asking to turn these off.

Every YouTube video I've watched with people who has a JBC station has said dealing with JBC has been an absolute nightmare.

So although your experience with Aixun is not great, it seems to be on par to what you would get with JBC (if not better), not great as it is.
I also suspect they can't fix this problem with the Aixun T3A, so they probably haven't responded because what can they say "Oops we f#cked up".

Anyway, my assessment on the lay of the land.
I don't think perfect exists at this point.

Would love to hear what you ended up going for?

Btw. any chance you could comment on that diode fix proposed in this thread, did you try it and did it do anything for you?

[floobydust]

The diode-add across the heater is clamp inductive spikes and protect the mosfet, it's running near max. I don't see it helping with this grounding problem but the TC op-amp is an alien so it might help it a bit.
My guess is it's the SMPS noise as well as crap firmware.

[tony359]

I ended up buying a JBC - Yes, I could agree it's a bit overpriced but... it works and because I am doing some paid work with my solder iron, I couldn't tolerate all those flaws I was having with the T3A and I didn't want to experiment more with other Chinese clones. It doesn't mean there are no other alternatives of course!
I made a quick comparison between the Aixun and the T3A.

Some of my viewers said they cannot measure voltage at the tip and they cannot make the speaker "sing" with their 6 months old station. Are there multiple HW revisions? Have they changed the design in worse?

[tony359]

Someone has brought this to my attention:



Check at 3:30. I believe Tony at NWR is using a T3A - but regardless, this is another example where "ground is in the way". There is NO WAY I want to see my expensive 245 tips glowing red like that. Shocking! It must be one of those FW where the station keeps spiking and never stops. Fair enough, later versions will detect and stop the uncontrolled burst, but will also hide the real temp at the tip.

[GnomeZA]

Someone has brought this to my attention:



Check at 3:30. I believe Tony at NWR is using a T3A - but regardless, this is another example where "ground is in the way". There is NO WAY I want to see my expensive 245 tips glowing red like that. Shocking! It must be one of those FW where the station keeps spiking and never stops. Fair enough, later versions will detect and stop the uncontrolled burst, but will also hide the real temp at the tip.

What is actually a bit sad is that they didn't fix this on the T320.
They went again for trying to solve the problem in software.

I've certainly not deep dived this issue to the extreme, but I'm fairly certain no amount of software can make a millivolt differential amplifier that is being interfered with suddenly reliable through software alone when you have no other information.

[tony359]

Indeed, I saw the review and it still shows issues.

I'm no electronic wizard but I agree with you, if the thermocouple is reporting rubbish you can only "mitigate" - that is, prevent the station from dumping 100's of watts into the tip. The tip won't glow red but it's unlikely it'll keep its setpoint.

I'm wondering whether they're fixing this quietly while they get rid of the old stock or developing a newer model or simply ignoring this whole matter

My curiosity is: is this an unavoidable side effect of using an SMPS or could this be avoided with a different HW design?

[elektryk]

My curiosity is: is this an unavoidable side effect of using an SMPS or could this be avoided with a different HW design?

I've got some custom stations SMPS powered and I didn't noticed such problems.
There were some good reviews about T3. I even thought about it, but the reviews here confirm that DIY was a good option.

EDIT:

Well, I was able to reproduce problem with my DIY station when negative output from SMPS (which also acts as tip grounding) was hard wired to the earth connection and touched metal central heating pipe with tip.
Problem didn't occur when I touched earth pin from power strip, which also made a ground loop but smaller, so it turns out that there was extraneous potential on the pipes and it did some mess.

[tony359]

Keep in mind that to reproduce the grounding issue I have to touch SOME pins of a GROUNDED circuit - not necessarily ground. (Even though when I later tested that, it would also misbehave when touching ground which was NOT happening before. No idea why)

It feels to me that some circuits might have the right combination of components and traces to create some noise which upsets the station.

When I  was using the T3A with my Hakko knock-off to remove SMD caps, I knew the ones which would cause the T3A to get crazy. Always the same caps. Not the others. Ever.