I don't see how you can like the internal build of such a product.
There's connectors glued with loctite (so they won't break) on one end, but there's wires soldered directly to the circuit board on the other end in the hand piece.
There's also wires soldered directly to the main board, so you have both connectors AND wires soldered directly
There's several kinds of connectors, i think i counted at least 3 different ones. I get that they need one with bigger separation between contacts for the high voltage stuff, but they could have used the same one for all the other connectors, with the same gauge wire ... there's red and black wires, there's the white wires with dashes of red, there's the connector with thin black wires
I would have used just one 3 pin connector
Then you have DIP socket for the main mcu but instead they could have used a double sided circuit board so they could solder the actual LED digits properly ... look how the pins go through the pcb and how they soldered those digits from the other side.
They went through all the effort to make everything through hole, only to have that single chip there surface mounted - guess that added an extra manufacturing process, an extra pass through a machine, and programming the weird orientation (not 45 degrees) ... unless they soldered them by hand (wouldn't surprise me)
If you give up and decide to use a surface mount chip, then maybe spend a few more minutes and put some pads for surface mounted resistors or maybe use surface mounted opamps or whatever and clean the board a bit...
There's a couple of 1w or whatever (bigger resistors) practically touching that to220 chip on the side, which is probably the regulator for the microcontroller.. and those resistors also touch or are very close to that capacitor cooking it over the life of the product... not sure what those resistors are used, i guess either to drop some voltage before the regulator does its job, or maybe as current sense (if it's regulator i guess they wanted to save money on a heatsink?)
There's also the triac heatsink touching that film capacitor, but I'm not sure that film capacitor is that much affected by heat
I also think it's kinda small area to run 700w+ through, where those mains connectors and where the triac is located.
And what's with zip tie squeezing all cables together, is it even allowed to bundle mains voltage and low voltage like that?