Aixun T3A overshooting?

[tony359]

My T3A is in a box. I wasted enough time with it. Happy to leave the excitement to others

[redwire]

Aixun Firmware Updates V1.36 out Jan. 23, 2024. "Fixed some known bugs" lol.
Place your bets! I predict FAIL

[tony359]

It could be.

When I discovered the issue I asked Aixun whether my unit was genuine and they did confirm it is. So if it's a reject, it's an Aixun official reject

Either way, it doesn't look good for Aixun.

[CapLeaker]

I think the partial problem is on AliExpress that some sellers sell rejects or barely functioning units. Got an original Garmin GPS display replacement once. It had a “ghost touch”. Factory reject.

[tony359]

What I discovered has been since confirmed by others so it's definitely not a fault with my station. The fact that later FW is "mitigating/hiding" the issue seems to confirm that they are well aware. NWR's video linked above is another real life demonstration that this is real.

Aixun only told me to wait until the tech department looked into the issue - never heard from them since. I suppose my video-reviews must have upset them (they were aware I was reviewing the station when I contacted them).

There are several theories behind this issue and obviously they are all HW related.

[redwire]

The chinese waste nothing, they will surreptitiously selloff bad product. I suspect you have a dud H/W revision, bad TC op-amp etc.
But the firmware is pretty bad alone. Do they admit any problem with the T3A? Do they issue a fix? Their silence speaks volumes.

[tony359]

You're welcome. I was very disappointed as when I looked online it looked a good product, a good alternative to a JBC. It's not. I have got rid of it and I have a JBC now. Maybe a bit overpriced, yes, but it doesn't glow my tips red.

Some of my viewers claim they cannot replicate the issues I have discovered on their stations. I don't know what to think.

[redwire]

Thanks Tony for putting the word out that Aixun is a junk product
Worse is they still don't have it fixed - or they are just selling off the bad design rev. to select customers.

I'd just buy a real JBC instead of this steel vs copper, aluminum socket connector, propaganda-conceal tip temperature crap.

[tony359]

oh wow! I think he uses the T3A as well. That's another great example that "earth sometimes is in the way". The tip went RED! Unbelievable!!!

Thanks for sharing that.

[harp]

It comes smart technology of future, see video on 3:30... my soldering iron with wooden handle not do that...
https://www.youtube.com/embed/8YiP559bVvw

[tony359]

Re: Aixun T3A overshooting?

Well, Aixun never came back to me about this issue so I made a video "non-review" of the station!

Let me know what you think!

https://www.youtube.com/watch?v=B7jLpHgR7fI

[tony359]

Re: Aixun T3A overshooting?

I believe it was a genuine JBC - but I might have also confirmed with the Aixun which came with the station. I'll double check.

Thanks for testing!

[CapLeaker]

Re: Aixun T3A overshooting?

Ok, redone the voltage measurement as you suggested, but at 0.5V I am still nowhere near the 1.5V. What elements did you get? Mine are made by Aixun with the black rings. Maybe there are low quality elements that are the problem? Dunno… I give up, as I can’t replicate the crazy behaviour of your station no matter what I try.

[tony359]

Re: Aixun T3A overshooting?

I don't understand why some units have that problem, while others not. I only had 0.05VDC measured coming out of my tip to earth ground. Could the problem be the T245 element itself? How else would voltage to be able to get on the tip?

I see you are using the station extensively so I don't mean to patronise you here, just clarifying things.

Voltage is only measured when the tip is actively heating. If I measure when it's keeping a stable voltage, I'd probably get the same reading.

To reproduce what I did, set one pre-set to 400C, then cool down the tip to 100C, then place your meter on the tip (not in auto mode, it won't be fast enough, I selected an appropriate range on my Fluke and set the Fluke to display the maximum reading).

Now the tip is 100C, select the 400C channel. The tip will be constantly heated for 3-4 seconds and then is where I measure the voltages I reported.

Yours definitely went crazy if you used that earth pin. Mine absolutely does not care if the earth ground touches the soldering tip. I've tried a few times now hooking the earth ground to everything I repaired.

I fixed a HDMI port on a PS5 today and used the earth ground. No problem. Voltage between the tip and earth ground was again 0.05V. Yesterday, I fixed a PA phone Paging speaker and a Motorola CDM1250 VHF. No problem then either. What gives?

Again, just a clarification: not an earth pin. Nothing happens if I touch an earth pin. It's "some" pins on a grounded PCB.

I don't know what to say though. I had that issue 10 minutes into using the station. 3-4 pins of each ISA slot would show the issue.
Then I was practicing on an XBOX on a pre-heater and the USB connector was buzzing loudly when touching the pre-heater itself.

What I am trying to say is that it feels like an obvious behaviour to me, I didn't do anything so special to see that.

They're trying to fix the hardware issue with software. What F/W rev are you running?

I agree with that.

I tried 1.34 and 1.33. 1.33 is "louder" but at least keeps the temperatures where they are supposed to be. Also 1.34 doesn't show "NO TOOL" when the issue happens but the power level goes 0-100 like crazy until the tip is on the affected pin.

Is the tip connected to PE? Or is it floating?

I read full continuity to ground but only when not heating. It could be because my Fluke won't like sensing voltage when in continuity mode though.

You could prove it by taking a say 10nF cap one leg to earth ground, and touch the tip to the other leg. If it freaks out then that is the problem.

Will try that thanks!

[redwire]

Re: Aixun T3A overshooting?

They're trying to fix the hardware issue with software. What F/W rev are you running?
You have a lot of noise on the temperature signal, you can only take a temp reading when the heater is off due to voltage drops in the wiring.
If you are skilled at writing real-time code, you can read the sensor and filter out noise before going into the PID routine. But... the firmware is not any good at that yet.

Is the tip connected to PE? Or is it floating?

Another issue I have seen is the SMPS transformer wound by some villagers end up really noisy with the primary coupling too much noise to the secondary. Or the SMPS is not stable.
Also the thermocouple op-amp can vary widely in quality. That was the cause of many problems with bad temp readings.

[CapLeaker]

Re: Aixun T3A overshooting?

I don’t understand why some units have that problem, while others not. I only had 0.05VDC measured coming out of my tip to earth ground. Could the problem be the T245 element itself? How else would voltage to be able to get on the tip?

Yours definitely went crazy if you used that earth pin. Mine absolutely does not care if the earth ground touches the soldering tip. I’ve tried a few times now hooking the earth ground to everything I repaired.

I fixed a HDMI port on a PS5 today and used the earth ground. No problem. Voltage between the tip and earth ground was again 0.05V. Yesterday, I fixed a PA phone Paging speaker and a Motorola CDM1250 VHF. No problem then either. What gives?

[redwire]

Re: Aixun T3A overshooting?

What is happening is the thermocouple op-amp is picking up noise due to the ground loop from touching the tip to something earth-grounded.
Usually this noise is from the SMPS, high frequency say 66kHz.
You could prove it by taking a say 10nF cap one leg to earth ground, and touch the tip to the other leg. If it freaks out then that is the problem.

There's a few ways to fix it.

[tony359]

Re: Aixun T3A overshooting?

I am.

But as you noticed nobody else seems to be so I’m not sure what to think ��

[harp]

Re: Aixun T3A overshooting?

Nobody concerned about 1.5A - 1.74A...?

[tony359]

Re: Aixun T3A overshooting?

It really needs a specific PCB and specific pins. Could it be that you didn’t stumble into that? On the mobo I was soldering only 4-5 pins of an ISA connector were showing the issue.

I’m 220V, UK. Not sure about the others.