I just got my YouYue 858D+ station from Aliexpress and did a teardown. The usual tomfoolery.
The wand, base, and box are all labelled "110V" but I found a (cracked) 220V heating element in it. Some math and I get 170W of heat instead of 610W!
A spare heater came free with the unit. 110V 19.8
(610W), 220V 71.6
(675W). I haven't installed it yet, as the heater has heatshrink tubing on the end, not silicone like the present element.
Power transformer is labelled "220V" but is OK on 110VAC.
858D06.PCB 2016.09.29 with MK1840D3 MCU.
I'm drawing a schematic and figured out the hardware, it's pretty basic.
Anyone with 110V version willing to check their heater resistance, see if my numbers are correct.