Aixun T3A overshooting?

[CapLeaker]

Re: Aixun T3A overshooting?

Ahh! Now I get it! I don’t use the ground wire! I don’t ground to the device I work on to the soldering station ever. What pencil station do you have? I have the fancy one where the tip turns off when the pencil is resting in the holder.

[harp]

Re: Aixun T3A overshooting?

Yes, general comment.

[tony359]

Re: Aixun T3A overshooting?

thank you - I am aware that by buying on Aliexpress it's a shot in the dark.

Just so that I understand correctly, what you point out is not relevant to the issue I am experiencing, just a general comment, am I correct?

[harp]

Re: Aixun T3A overshooting?

Yes ground clip is mounted on the station. I used that for my measurements as I read 0.7Ohm with mains ground so it does seem to be a direct connection.

This is not solve your problem, but be aware of chinese creativity - they may using a aluminium or ferrous wire instead of copper, and to do so is offen only plated with copper to look like copper wire... the wire have noticable resistance (about you measured) and heating while carry more amps (car bulb etc). Also, they regulary ommit soldering wire to aligator clamp, and contact is not reliable, like to coroded due to difference in material potencial...

On pictures is wire that hang on regular magnet - this is my test and later I do a label of this wire with "Fe".

[tony359]

Re: Aixun T3A overshooting?

Look for something copper that is bigger like a copper pipe / sheet and see if you can solder to that.

.

I believe you might be suggesting that the issue happens when the PSU is being driven harder.

I can assure you this is not the issue. On the latest video I am barely touching a small solder joint - it doesn't melt as there is no flux and it's oxidised - and it misbehaves immediately. The spike you see on power is caused by the issue and not vice versa. The very same solder joint doesn't trigger the issue when the PCB is not grounded.

https://www.youtube.com/watch?v=8OXDOZTy7t0

Anyways, yes I did try the 5p copper coin test. I've melted 10cm of solder on a 5p coin and waited until it flows on the whole coin. It takes 40 seconds while with my old station it takes 100 seconds. That's why I really like the T245!

But I am pretty confident it's not the PSU.

It sounds like you've never experienced this issue yourself - would you think you're soldering on grounded PCBs sometimes? Again, it's not touching ground itself which causes havoc.

Thanks for now!

[CapLeaker]

Re: Aixun T3A overshooting?

Thanks.

no power, just ground. No batteries on the board.

And if someone said "disconnect it from ground" then my question is "so the T3A won't work when I am pre-heating a board as the pre-heater is grounded".

Do you have a T3A as well?

Yes, I do have the T3A and run the T245 and the T12 pens and elements. I can solder copper pipe, or something that has a ridiculous heat sink on it with my T245 no problem.

Look for something copper that is bigger like a copper pipe / sheet and see if you can solder to that.

When I saw your video, it seems like each time the T3A heated the pad a bit harder, I could see the T3A ramping up heat fast and in the peaks is seems to go “crazy”. Yours does it every time the power demand from the pen is high. Check it out and see if you can verify this.

[tony359]

Re: Aixun T3A overshooting?

Yes ground clip is mounted on the station. I used that for my measurements as I read 0.7Ohm with mains ground so it does seem to be a direct connection.

I thought the same, that station would be able to damage some sensitive stuff.

I hope someone can help me, I have to get back to the seller tomorrow though to report the issue. I'll make a video explanation and let's hope they don't BS me or offer a partial refund...

[harp]

Re: Aixun T3A overshooting?

Station GND to Mains: 0.26AC on one mains leg

Ground clip is mounted on station gnd? (that black aligator ground clip that you show on video)
I ask because it is possible that ground clip have loose resistive conection with wire - ground clip must be 0.0Vac to earth ground, otherwise it is not well grounded.

The measure is very suspicious, its look like major leaking, and I am not expert to give value conclusion, but yout tip may damaged some sensitive devices, maybe is best to do not use that soldering station till somebody with identical model compare and confirm measure reading...

[tony359]

Re: Aixun T3A overshooting?

Here are the measurements

GND to TIP resistance is 0.7Ohm when the station is off (my leads read 0.4 Ohm when shorted).

If I take the tip to 100C and then ask the station to go to 400C - so the tip is heated constantly for a few seconds - during that time my Fluke measures OL.

When the tip keeps the temperature steady, resistance jumps around, clearly when the tip is being heated continuity to ground is lost??

VOLTAGE

GND to TIP: 0.584V AC when heating (same trick than before)
GND to TIP: 0.915V DC when heating (same trick than before)

CURRENT
GND to TIP: 1.5A DC when heating (same trick than before)
GND to TIP: 1.74A AC when heating (same trick than before)

MAINS check
The chassis is indeed grounded and the GND clip too.

station GND to Mains GND: I do have continuity
Station GND to Mains: 0.26AC on one mains leg and 242VAC on the other.

I'm not sure I should read that amount of voltage and current on a soldering iron to be honest. My older iron doesn't read anything like that, it reads 0V at all times.

[harp]

Re: Aixun T3A overshooting?

Please do some measurement, voltage and current (carefully) accross your ground clip and soldering tip, both ac and dc?

Also check voltage of your ground clip against mains socket, with one pin should be 240v and with another 0.0v (earthed from distributor)

[tony359]

Re: Aixun T3A overshooting?

Thanks.

no power, just ground. No batteries on the board.

And if someone said "disconnect it from ground" then my question is "so the T3A won't work when I am pre-heating a board as the pre-heater is grounded".

Do you have a T3A as well?

[CapLeaker]

Re: Aixun T3A overshooting?

Is the device you solder on connected to power mains? Other than that it doesn’t make any sense what your saying. None of my soldering irons do that.

[stj]

Re: Aixun T3A overshooting?

it makes no sense.
the tip resistance to mains earth should be almost zero

*unless* it's floating for safety - but i dont think they did that.
weller in the past used to connect the tip to mains earth through a parallel resistor and capacitor to limit current incase you accidentally worked on something live.

i modded my t12 the same way - sometimes i can get leds to glow while soldering them now!

[tony359]

Re: Aixun T3A overshooting?

Shall do, I did check that the unit was earthed, I believe everything reads full continuity but the tip which is reading some resistance but not much? I'll double check.

Bear in mind that when I touch ground directly with the tip, it does not happen. It only happens when touching SOME solder joints on an earthed PCB.

I'm not sure about the PSU to be honest. The display would show "undervolt" or something like that, like it does for a brief moment when you power it off.

Someone on EEVBlog says this is normal - I can't accept a soldering iron which cannot be used on grounded equipment, would you agree?

[stj]

Re: Aixun T3A overshooting?

contact Aixun - it's gotta be a psu issue
my guess is the ceramic capacitor between the primary & seconday is missing or the unit is missing a ground connection between the mains earth input and the handle somewhere.

can you use your meter to check resistance between the iron tip and the earth pin on the back of the unit - earth on the iec connector i mean.
while your at it - check your power cable and your house socket

i'v had a few recent "incidents" with power cords with molded plugs on them!!!!
if you buy anything high wattage with a molded plug - check the plug isnt getting hot while it's running - specially fan heaters from Lidl!!

[tony359]

Re: Aixun T3A overshooting?

I have an update. It's ground.

When the PCB I am soldering is grounded, SOME solder joints will cause havoc.
AND, the handle is buzzing.

https://www.youtube.com/watch?v=8OXDOZTy7t0

[tony359]

Re: Aixun T3A overshooting?

I don’t think it’s got to do with power, I’m barely touching some specific joints. I’ve done the ‘coin’ test with lots of solder and I can dip the tip in a wet sponge and it doesn’t happen.

Yes it’s brand new so o guess I’ll ask for a replacement, wish me luck.

Still, I can’t think of what could be sensing that is triggering that behaviour.

[CapLeaker]

Re: Aixun T3A overshooting?

Mine doesn’t do that. I even soldered big stuff with that iron that shouldn’t be done with one. I am not even sure what firmware or hardware mine is running, but it is about 10 months old now.

Looking at your video, it looks like it’s going crazy as soon the main unit ramps power up close to full tilt, losing juice. Weird. If you just got it and depending where you bought it, warranty it?

[tony359]

Re: Aixun T3A overshooting?

I read online that the new version buzzes more than the old one. Mine says "HW version 1" (or maybe 0?) so not sure. Interesting

However I have a much bigger problem.

I've used the T3A to do some soldering tonight and noticed the display would say "NO TOOL" every now and then. I thought it was my JBC tip so I swapped it for an Axiun. Same issue.

Then I realised it was not the tip. EVERY time I was touching some specific pins on the motherboard I was working on, the station does what you see on the video.

The MoBo is disconnected, been off for days, no battery.

How is that even possible please and, most importantly, what do I do now?
I am incredibly confused.

https://www.youtube.com/watch?v=o5JEp6sO9Jc

This is what the display says when it "flashes"

[CapLeaker]

Re: Aixun T3A overshooting?

No buzzing in mine.