I’m a soldering god (temporarily)
The toothbrush is already lying next to the mother’s defective router, waiting to be taken to the recycling center. I pick it up again and consider that it’s already broken and can’t get any more broken because of my lack of soldering skills. Later in the day, I’ve been drinking a lot of iced coffee because of the heat, I get the urge to do something, I look for the tiny SMD component that has crumbled off in the basement and I find it. It is only two square millimeters in size. Even with the mother’s large magnifying glass, I can’t tell if it might have a helpful note on the installation direction on it.
I take a very thin soldering tip and a pair of crooked tweezers from my cheap-looking but really many parts gift soldering set.
I don’t know how to solder, I briefly tried to watch a YouTube video on the subject, but after several minutes of introductory skipping, the explainer’s nest soldering iron was still cold and I gave up again. I remember that you really should only heat one side and not the other, or anything first, or something.
I heat everything up at the same time until the tiny thing sticks back on the circuit board.
The toothbrush doesn’t work.
I’m randomly soldering on a spot that I desoldered last time only because the iFixit guide (for a similar toothbrush) mentioned three spots to unsolder. However, this third digit is not visibly connected to the battery, so maybe it is needed for something else after all.
The toothbrush still doesn’t work.
I unsolder the crumb to solder it the other way around, but I drop it, and now that the illegible writing has melted I can’t remember which way I tried before. I kind of solder it back on.
The toothbrush still doesn’t work.
I unsolder the component, this time holding it firmly with the tweezers, turning the toothbrush around under it and soldering it back on.
Now the toothbrush works again. I’m a soldering god!
The original battery problem is still unresolved, but thanks to Dokape’s reference to my last post, I now know how to fix it. Five minutes later I have the battery in my hand.
I found out from some instructions (which I couldn’t find any more at the time of writing) that you can also solder an old power supply unit with approximately the right volt specification to the battery connections on the circuit board instead of a battery. Then you have an electric toothbrush with a cable and you can’t go far from a socket when brushing your teeth, but you will never have an empty battery again. I find a reasonably-matching power adapter from a pre-smartphone era cell phone, cut the cable at the plug, and strip the insulation from the ends. Using a hand-powered wood drill, I carefully drill an extra hole for the cable inside the plastic case and less carefully an extra hole in my foot. I can’t tell from the labeling of the power pack which cable belongs to which pole. It only says which pole on the plug is on the inside and which is on the outside, but the plug has already been cut off and does not reveal which cable color belongs to the inside and which to the outside. I first solder the cable ends this way and then the other way around on the board. Neither variant works.
I give up and order a new battery from Ebay. It has twice as many mAh as the old one.
A week later the new battery arrived. I solder it in, but the toothbrush stays dead. I probably destroyed something invisible beyond repair during the power supply experiment and now I either have to wait until I grow even more superpowers or buy the same toothbrush again. I have a spare battery now.