I read here that there are problems with adjusting the temperature. But that's not correct. You can write down your values that are actually present at the set 100, 200, 300, 400 and 500 and then enter them in the menu, the stored curve is then corrected immediately, although nothing else is displayed when you call up the menu again. So you think that nothing was saved, but that's not true, the curve was definitely corrected. I even find it advantageous that you can correct the curve over 5 points if it is not so linear. But you can also only enter a value for 100 and 500, then it is just a straight curve.
I've also had the T3A for a few days and use original JBC tips from TME, I haven't tried the 3 Aixun stock soldering tips yet.
With the unprotected µC I/O pin, I will fix it with a diode from the I/O pin to VCC and from GND to the I/O pin and a resistor, don't think that such a big effort with an optocoupler is necessary.
Furthermore, I wrote to support@jcprogrammer.com and info@aixuntech.com whether it would not be possible 1. in a later firmware update to offer a setting for the overshoot or short-term overboost in the menu. 2. Offered to translate the menus into German for free. 3. I asked if you could delay the transfer of the set temperature from the storage locations by 1 second so that when you switch from 2 to 1 you don't select the higher temperature from storage location 3 for a short time and heat up unnecessarily before you reach storage location 1.
Let's see if anyone reports.
Here I just saw how the pin for detecting the sleep mode is wired.
https://github.com/c0d3z3r0/aixun_t3a_rev/blob/master/schematics/aixun_t3a.pdfIt has an external pullup and the diode only allows the pin to be pulled to ground, so an overvoltage should not be able to reach the pin at all due to the diode.