Braun Type 3709 Toothbrush Auto-start Issue: Cannot Turn Off, Damp Inside, Button Functions Fine

The toothbrush started to turn on by itself, after the same activation it cannot be turned off as if the button does not work. I decided to undress it, it turned out that it was damp inside.
I wiped dry as much as I could, I left it undressed for a few days to let it dry well, but it did not help.
The effect is that the brush turns itself on when it wants to (worst when it turns on at night and you can't turn it off), sometimes it lies for half a day and turns on for no reason, it just lives its own life and I don't know what drives it.
The button works fine and I checked the crossing with a meter every time.
Several times it happened that it reacted as necessary to switching on and off several times in a row, but not for long, after a while it starts to go crazy again.
I tried to capture its excesses in the video and it did a little.
The brush is 9 months old, but I lost my receipt and the warranty is forfeited.
All February looks good, the battery is not loose, everything looks good to a layman's eye.
What could be responsible for this state of affairs?
Could the system be wet?
Can it be repaired?

Maybe I will not help too much, but I will answer the question whether the fault could have occurred after flooding - Well, no Braun's brushes have a factory defect in this respect ..
Many copies have a problem with this, some are even in the store ..
Under the warranty, Braun did not undertake repairs, but exchanged them for new ones - I also advise you to look for the receipt again ..
Some time ago I had a customer with such a brush fault, unfortunately the brush started at the airport Naturally, he did not have time for the plane

nioop wrote:

Maybe I can't help much

You just helped a lot. This explains why everything seems fine and yet something is wrong. With this airport dobreee

Hello,
Has the problem of self-actuating the toothbrush been resolved? I have exactly the same and I don't know what to do. The receipt is probably forfeited (and the warranty). I have two brushes, but only one behaves like that. I thought to disconnect the battery first, but I don't know how. It often turns on by itself and I have no way to turn it off. The engine heats up (it will eventually fall ??) and it can not be turned off. When it finishes, it works normally.

Thanks in advance for reply.

Kisses dQs

The problem could not be solved.
When the brush turns on by itself and you cannot turn it off, just put it on the charger and it turns off by itself. As long as it is charged, it will not turn on by itself, at least that was the case with me.
You can undress it by grabbing the upper part with pliers (through the cloth), the one on which the replaceable head is pressed (of course, you need to remove the head first) and turn it to the left.
Mine doesn't turn on at all now. Neither by itself nor with a button.
Battery charged and zero life.

Dry the agent, wash with isopropanol, reassemble and it will work. Well, the problem may be with the rubber of the housing in the area of the button, it loses its properties and becomes less flexible, which may result in spontaneous pressing of the microswitch. These brushes do not have other reasons for their self-switching on.

Nothing is pressed arbitrarily. The brush can turn on without any reason or outside interference. It only does not turn on when inserted into the charger (induction), only then you can sleep at night ?

The rubber stiffens in the place where the switch is and as a result it presses on the microswitch ... I do not know whether it will be arbitrary or involuntarily or against the user's instructions.

I understand, but it turns on even when the housing and the rubber are removed. See the video at the beginning.

I took the brush apart, it turned out to be easy. Inside it was dry and clean so the humidity was not the cause of the problem. Two integrated circuits on the board. The micro switch clicks nicely. The battery is like new, I bought the tips and it looks like you will have to say goodbye to it ...

Hello,

A bit late, but I managed to save my toothbrush. I have a slightly different PCB model, but I can see that my colleague has the same damage.
In my case, it helped to recreate the path from the switch to the control transistor.


The non-contact path probably works like an antenna, collects noise by slamming the base / gate (I did not check the type) of the transistor and the brush starts itself.
In my colleague's case, it does not look bad yet, I had a literally black, fragile solder mask.

If it did, it would be really good news. It's a pity to throw it away, it's almost like new, and here's the problem ...

For me it was so much easier that in my model there are thicker paths than the button, so I scraped off the solder mask and soldered the whole thing.
At a friend's, it is probably easiest to use a kinar or enamel wire. For the sake of peace, I also replaced the button and corrected the uncertain February.
And also advice. It is best to unsolder the tape from the link at the beginning so that the brush does not turn on during the repair. The easiest way to do this is in the lower part where the charging coil is.

Hello.
I connect to the topic. A few days ago my toothbrush died, i.e. it stopped responding to the button. After a few days of trying to turn it on and charge it, she came to life for 1 day and died again. I found this post and decided to undress mine as well. As it turned out, the brush turns on only when I touch the tip of the scissors in one of the 4 marked yellow places. The toothbrush still does not respond to the switch. I can only turn it off by touching one of the 4 points again. Do I suspect that to replace the switch? Do you know what I can replace and is it enough to desolder and solder a new one?
Thank you in advance for your help.

And did you check the switch?

Just by pushing. What other check do you mean?

The hands drop. A gauge. After all, not with a hammer.