Author Topic: EEVblog #284 - Braun Toothbrush Teardown  (Read 17593 times)

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Offline amyk

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #25 on: June 02, 2012, 11:32:10 am »
Yeah, there was a bit of crud around the bottom of the brush. But I guess the only way they could make it absolutely watertight is to seal the case completely in wich case you could not replace the battery. The electronics in Dave's brush still work so it doesn't seem to be a big problem.
The moisture comes in from the top, where the shaft meets the housing it doesn't seal well. My ideal design would be a brushless motor with a rotor in the wet part and the stator inside the housing (which would not need a hole into the interior), like those used in aquarium pumps. The downside is that it requires more power and control electronics than a regular brushed DC motor. Sealing the bottom and buttons isn't difficult even with replaceable batteries, since they make waterproof torches in the same form factor with an o-ring and threaded cap.
 

Offline madworm

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #26 on: June 02, 2012, 11:55:52 am »
Perfectly sealed toothbrush units... that's never going to happen.

Less opportunity to rip off the consumer, just like with inkjet printers that "suddenly" require maintenance because some nefarious droplet counter has reached its maximum value.

Quote
The sponge used for head cleaning might be full and overflow.

The "service" costs 5x more what a new printer costs and the fact that this "error" is software resettable is kept a secret and/or the tools are not available to the end consumer.
 

Offline saturation

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #27 on: June 05, 2012, 12:23:20 pm »
I've been using Sonicare since late 1990s, before they were bought by Phillips.  I've never had a problem with them except the batteries dying.  Its very annoying because since the discharge rate is fairly slow, the batteries can not be deep cycled or reconditioned to get them back up to speed.  So, by 2 years, you get only half the rated AH, and the battery slowly deteriorates from there. 

4 years ago, Sonicare came out with the only AA powered version; sans inductive coils and batteries the thing is cheap and lightweight.



Because the motor is identical to the sealed brushes the brush power is identical, and you don't have the charging issues.  Instead, most folks don't know how to seal o ring joints properly, leading to leaks.  Its not entirely user friendly that way, because an o ring seal must be impeccably clean for it to be watertight, else the o ring will leak where the dirt is.  That said, my brushes have served me well for over 4 years without leaking, I have 2, so that comes to nearly 8-product years of use and I submerge these brushes in 4" of water during cleaning, which is every use.

Never drop an electronic toothbrush.  They are not built with shock/vibration resilience and the extra mass of the batteries when it falls will add to the injury.  A tiny droplet size leak is an other wise water tight casing means very slow to nil drying out, and inevitable death. 




Best Wishes,

 Saturation
 

Offline vk6zgo

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #28 on: March 25, 2013, 02:12:47 am »
I know this is an old thread,but I just had occasion to look at my electric toothbrush.
My daughter bought it,don't know where,it worked for about 3 minutes & stopped,never to go again.

It is a Braun,even though it also says "Oral B" on the handle.
The charger is about half the size of Dave's one

Same waveform from the charger, frequency looks to be about 25.6 kHz,but the last time the Tek 7613 was calibrated,Ronnie Reagan was in the White House!

Tried the unscrewing technique,but it just slipped around on the "peg" protruding from the charger.
Looks like it is fully sealed,so no fix,& only a fully destructive teardown possible -----bummer! >:(
 

Offline amyk

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #29 on: March 25, 2013, 09:39:31 am »
I know this is an old thread,but I just had occasion to look at my electric toothbrush.
My daughter bought it,don't know where,it worked for about 3 minutes & stopped,never to go again.

It is a Braun,even though it also says "Oral B" on the handle.
The charger is about half the size of Dave's one

Same waveform from the charger, frequency looks to be about 25.6 kHz,but the last time the Tek 7613 was calibrated,Ronnie Reagan was in the White House!

Tried the unscrewing technique,but it just slipped around on the "peg" protruding from the charger.
Looks like it is fully sealed,so no fix,& only a fully destructive teardown possible -----bummer! >:(
It might just be a usual buildup of gunk around the base. They're built to be waterproof so the seal is tight even without the gunk.
 

Offline vk6zgo

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #30 on: March 25, 2013, 02:41:47 pm »
No gunk,it's virtually  brand new!
 

Offline Fezder

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #31 on: April 22, 2013, 05:00:01 pm »
just saw this video, nice! especially i liked ''scope probe-hack'' :D
Both analog/digital hobbyist, reparing stuff from time to time
 

Online madires

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #32 on: April 22, 2013, 06:11:41 pm »
Tried the unscrewing technique,but it just slipped around on the "peg" protruding from the charger.
Looks like it is fully sealed,so no fix,& only a fully destructive teardown possible -----bummer! >:(

Seems to be the same model like I have (Professional 2000). Just after about 50 charge/discharge cycles the battery lasted only 4 days. At the beginning it was about 7-8 days. While searching for a way to open it (unscrewing method doesn't work) I stumbled across a recycling hint in the Japanese manual. The bottom part is fixed by a pair of snap-in thingies. You can open it by creating a torque with a large screwdriver. Afterwards it won't close as precisely as before but the sealing gasket is good enough to prevent any ingress of moisture. And it will open quite easily the next time :-) I replaced the 4/5 AA NiMH and I'm curious if the new battery will perform better than the original one after 50 cycles. 50% after 50 cycles is a bad joke! Never had such a bad rechargeable battery.
 

Offline AndersG

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Re: EEVblog #284 - Braun Toothbrush Teardown
« Reply #33 on: August 08, 2019, 12:39:21 pm »
Sorry for arriving late to the party, but I took apart a Braun charger and it is indeed potted, but I managed to strip the coil and ferrite and measure dimensions:

It is wound with 0.3mm wire on a bobbin OD 17mm, ID 7mm, h 5mm. Inside the bobin, there is a ferrite dia 6mm h=18,5. Plain wire, not Litz.

I created a quick and dirty Class-e/push-pull/multivibrator and wound my own coil. Image shows my mesurement pickup coil over the transmitter coil. Works a treat. It charges one of our brushes in 45 minutes and I also tested with a discarded brush. Measured the charging current which was approx 70mA into a rather tired battery with the original charger and 100mA with mine.
806022-0
806028-1
806034-2

Now, why would anyone do such a daft thing? Well, I need a charger that runs off 12V in my boat :)

I also need to be able to turn it off after charging. The resulting output is much cleaner than the original. First overtone at 60kHz is -36dB down and second if -26dB down.

« Last Edit: August 08, 2019, 12:47:37 pm by AndersG »
 
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