The 40V angle grinder PCB (Patreon)

Published:

2022-12-01 05:26:54

Imported:

2023-02

Content

Kinda complex and interesting. Getting the PCB out of the housing was not fun at all, as it must be soldered in position due to side indents that stop it being slid out after the contact retaining bar is removed. I hacked the indent ridges out so I could slide the whole assembly out and then desoldered them individually.

The dovetail contact retaining bar was also glued in and required heat and force to get it slid out.

Most of the circuitry is for deriving power supply voltages and controlling the MOSFET. I've just done a quick test on the battery and the NTC pin seems to be pulled to 0V, so maybe the processor tries to pull it high and the pack pulls it low to enable operation.

The battery pack will be getting its own video.

https://www.youtube.com/watch?v=hlUrQWefEjg

Files

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This is the PCB from a Ferrex 40V angle grinder from Aldi. I did the mechanical teardown in another video, so now it's time for its control PCB. This PCB has two main functions. It gives a ramped soft start to the tool and also detects the control signal from the 20/40V battery to indicate when it is low on charge or overheating. I don't think the battery itself has any ability to switch power off to the tool. It will be explored in its own video. The bulk of the circuitry is for internal voltage regulation and MOSFET driving, with other simpler sections detecting the switch being turned on or off to facilitate doing another soft start reliably with each switch operation. Reverse engineering this was made a lot harder by the way the PCB is soldered to the battery blades in situ and the fact that a section of it was covered in an unusually resinous silicone-like coating that was very hard to remove cleanly. Mid-play video-adverts are annoying in technical videos, so I don't enable them. If you appreciate that and enjoy my content then you can help support the channel with a contribution of a dollar or two a month on Patreon. That also lets you critique the (advert free) videos before they are released, gives a more direct means of communication with me and also gives access to the regular relaxed Patreon live streams. https://www.patreon.com/bigclive #ElectronicsCreators