I was soldering on a pre-heating board today, the PCB was touching the plates and I could hear some buzzing noise from where it was touching the plate when I was soldering. I love this iron but I am not impressed by the design so far.
Ooooooooh, I remember something....... can you try touching the connector at the main unit with the metal ring of the handle while a tip is inserted? I bet you'll hear that buzzing noise as well... I think I had mentioned that somewhere in the thread but can't find it right now
EDIT: found it: https://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg4417474/#msg4417474
Large ceramic input capacitor is smaller than electrolytic capacitor with same values would be but the ceramic capacitor “sings” audibly
interesting. But the buzzing I am hearing come from the handle (or in the aforementioned case when the handle touches the front connector shell). I don't hear much from the station or very little.
what i would say is that even with a correct types of metal prying tools then it's still some degree of risk, and a bit tough task, but also certainly not outside the typical smartphones repair doctrines. and several of us have successfully removed it. although at least 1 guy reported chipping the corner of the glass (i didn't)
At this point, I'm starting to suspect all Aixun's buzz by design. And that most users don't really notice it because it is a really faint buzzing. But you would hear it if you put your ears close to the handle or the case, or when the room is quiet. I'm curious if someone with a "silent" Aixun can test this theory.
After an hour of combat with the pesky glass screen, I have been defeated.
Managed to destroy my prying tools and crack the screen. There is just no room for any tool to get under the glass and pry it off. The way it's installed, the case forms a lip that encompasses the glass, making it impossible to get under it with any prying tool. The suction cup was just hopeless given how strong the bonding material is, even after being heated all the way to 250C. I measured the glass to be about 1mm thick, with the spacing between glass border and the case lip about 1/10 of a mm. Good luck sliding anything under from around the glass. You need a MEGA suction cup and an astronomical force to pry it off without damage.
The good news is that the seller said he will send me a replacement glass cover. So I'll be waiting for that.
In the meantime, now that the damn thing is open, I'm gonna head over to the lab to see how far I can get in debugging the buzzing issue. Ironically, I'll need a proper soldering iron to work on this one.
The way the circuit works has buzzing noise as a consequence but not everybody notices that. Also some units might be more prone to buzzing for mechanical tolerances. And finally, I noticed 1.33 buzzes louder than 1.34 so it also depends on how the element is driver I guess.
Thanks for the analysis, really cool to see!
Yes, yes and yes. And also there are multiple things buzzing. At least we know that the control board and the handle are buzzing. Then we have that weird buzzing when the handle metal ring touches GND/connector. And the third thing: I realized that my SMPS is buzzing as well, not too loud, though
Yes, yes and yes. And also there are multiple things buzzing. At least we know that the control board and the handle are buzzing. Then we have that weird buzzing when the handle metal ring touches GND/connector. And the third thing: I realized that my SMPS is buzzing as well, not too loud, though
I wonder if there's a way to make this circuit softer
So that the edge of PWM
looks more like this
The sharp edge switching 150W at high frequency is probably causing a ton of EMI and mechanical vibration which is probably what we are hearing. I don't mind losing some power in the switching MOSFET, as long as I get rid of buzzing and/or mechanical stress to the whole circuit.
I don't think PWM is required at all
I don't think PWM is required at all
Right, but I'm thinking about modifying the Aixun in its current form to solve the buzzing problem. The current firmware uses the PWM, so there's not much choice there. But if the edges of the PWM become softer, either pre switching via LPF on Q4, or post switching via an inductor or such, maybe there is hope of lowering the sudden change in magnetic fields that causes vibrations.
I managed to remove the front panel glass with 140 C degrees (PG8018lcd with narrow nozzle) and standard metal 0,2mm prying tool.
Aixun should mount the panel by screws not by tons of strong glue.
For example, look at the way Unisolder does this:
There is a low-pass filter consisting of R6 and C85 on the gate of the switching MOSFET. Furthermore, the NPN (Q4) driving the gate has its own low pass filter via R17 and C10.
Do they use PWM? If yes, what frequency?