Electronics > Repair

ES120 Electronic Screwdriver repair

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Hello Gentlemen,

I've got a miniware ES121 electronic screwdriver which turns out to have the board of an es120 (the predecessor model) which stopped working with a weird failure mode. I guess it would be a simple fix once I manage to identify the components.

Failure mode can be seen in this video: https://imgur.com/a/sSy0t2O.

Essentially what happens is I press the button, start turning the board so it would initiate the motor turning the same direction. Motor starts turning and quickly stops. On the bottom of the screen you can see an indication bar about how fast the driver spins. At the beginning the bar is full, when I press the button it becomes empty, if I rotate either direction it starts to increase and the motor starts spinning, until rather soon both the bar becomes empty and the motor stops. What is interesting is that when I disconnect the motor the bar stays empty and the screw keeps rotating in the direction I turn the pcb, indicating that the accelerometer is working just fine and the fault is to be found somewhere else ...

here's some pictures of the pcb with readable component marks:

The qfn above the stm32 labeled AGD2 would then be the accelerometer, which according to the findings above should also not be at fault.
The other 3 sots near the usb seem to provide power for the mcu, which works fine.
Due to the proximity of the battery connection I guess the 6 legged SOT IC with the inductor and two diodes just below the display and on the right side of the button is the charging circuit (which works fine)
Which leaves the Motor driver in the bottom portion of the PCB labeled MX630B which I found the chinese datasheet for: http://www.szxunrui.cn/siteimages/9904/2020041310424734.pdf

Has anyone done had this kind of problem/done repair to this device before?
From what I see here I guess it can only be the motor driver. I am kind of hoping to be able to find a drop-in replacement of better quality.
Any ideas, inputs or maybe spotted mistakes in my analysis would be very welcome!  :-/O

EDIT: I have just found that it is actually more likely that the suspected charging IC is actually a boos converter, since motor driver expects VDD in the range of 7.2V-9.6V. The markings of that IC are BC8nX, photo here:

I think I found the part: https://datasheet.lcsc.com/szlcsc/1811151230_MST-MST9220BSF_C324586.pdf
If correct it's indeed a boost converter. The markings make sense (BCY1W2X3 Remark: 1=Production year, 2=Production week, 3=internal code) and the pinout seems to be reasonable.

Hi, I have the same problem.
How did you solve it by replacing the boost?

The same problem...
Dear 0xde4dbeef, please tell... did replacement of boost converter help?

Unfortunately that boost converter has been unobtainable for me so I never got to try. Did you check if your screwdriver uses the same IC? Chances are miniware had to switch parts as well ...


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