Repairing your Sonicare

This thread has changed from a take-it-apart project to lots of advice on how to fix a Sonicare and put it back together. I hope all the great comments below help people bring their toothbrushes (or lockpicks or glass etchers or whatever) back to life.

Step 1 Overview

Circuitboard with on/off switch, two AA size rechargeable batteries under.

Comments

[skylimey]

Hi Guys, My HX6930 died, so I pried the bottom plastic plug out of the base and the entire assembly fell out of the plastic toothbrush. Its a hi-power Ni-Cad (SE US14500V) and I'm guessing mine died because it's all wet inside. The battery seems to be in pretty good shape, so if it dries out, maybe it'll start working again. I just need to waterproof the gap between the head and the plastic. M

[ARS1111]

The Internet says that "SE US14500V" is a Lithium-Ion battery. Also, AFAIK, your model is a Flexcare series unit. Philips says these about Flexcare batteries:

"FlexCare uses Lithium Ion batteries. The batteries will last for many years of regular use. The Lithium Ion batteries inside your FlexCare toothbrush cannot be replaced. However, when they no longer function, they are easily removed for disposal, along with the handle. These Lithium Ion batteries do not contain heavy metals like Cadmium in NICD batteries, so they are much less hazardous to the environment. But they do need to be disposed of safely.
Do not throw away your brush with normal household waste at the end of its life... [...Here was the instructions how to dismantle the unit and remove the battery for disposal...]"

[davejohnson01]

Skylimey, how did you pry off the plug on the bottom?

The metal post on my HX6910 came loose and I want to see if I can fix it.

Thanks
D

[fractalthinking]

Most of the time, only the first cell of a NiCad battery pack is bad.  

NiCads develop "wiskers" which can be fixed/destroyed by running higher than the normal voltage of 1.2v across them intermittently.  

It is greener to try to fix it rather than replacing it.  

In this instance it was also much easier than desoldering and replacing the battery.

I usually use a 5V wallbrick and some tape to attach leads from the 5V plug end.

I was able to fix mine with the battery in place.  1.3V after I  "sparked" the bad cell with 5V.

Taking the sonicare apart was the most painful part.  It was a bloody affair after the utility knife slipped.

The plastic also fractured. Now I have to make sure moisture does not get into it.

[tmaiorca]

Like magic. But I still don't like it that they don't let us replace the batteries without the rigmarole. Boo to Sonicare! Careful with that axe Eugene. Thanks for the post. I saved about $60.

[jimluschen]

I like Pink Floyd too!

[caisson]

Great repair guide re Sonicare Advance. I repaired 3 of them using the guide. My two-cents:

1. Do NOT unsolder the pins. You may damage the circuit board. Instead, just cut the pins about mid way, to detach the circuit board. Why? See Note1 below.

Putting it back:
   Use a 35W-40W small soldering iron with small, thin and sharp tip.
   Wrap then solder short thin wires to all the solder points at the device side, not to the circuit board. Naturally, use insulated and thin small wires.
   Align the board and solder the cut pins together. This holds the board in place, for physical strength as well. Use more solder on the pins for mechanical strength.
   If you cannot access the inner pins. Leave them unsoldered.
   Now solder all the short thin wires to the circuit board, copper foil side. All of them. The added wires help electric connectivity in case the solder on pins develops cracks. (There is whole lot of shaking!).
   As you can see, the inner pins that you did not solder, now has connectivity via the wires.
Electric current is small, about 80mA, you can use as small a wire as you can. Make sure it is insulated though. Again, lots of shaking may rub away too thin an insulation.

2. Use Xacto knife (or small thin knife) to scribe along the 2-halves on the inside of the screw-in head portion.
This helps to ply open the 2-halves without cracking the thin plastic there. The smoother that plastic is, the better. The vibrating magnet of the brush head rests very close to it.

3. When gluing the 2 halves together, use rubber bands to hold them together. Use your finger to smooth out or clean out the glue inside of the screw-in head area. Make it as smooth and clean as possible.

4. I would not recommend silicone glue.
It has ammonia. The acid attacks circuit elements and creates corrosion on circuit boards.
   Best is use acid free glue ("do not harm photo" type).
   One good example is Scotch Quick Drying Tacky Glue by 3M.
   You can get it at Micheal's or other arts suppliers.
   I use acrylic caulking, and use drops of Scotch Tacky Glue on corners and pressure areas to help holding the halves tight.
The acrylic caulking inside the screw-in area is much easy to clean out, yet water tight. It would be a mistake to glue this special area tight. If you open it again, the tightness may break the thin plastic here. All you need here is water tight, not glue tight.

5. Use 800mAh or higher NiCad, **NOT** NMH, Nickle Metal Hydride, battery. (Original is 700mAh NiCad.)
    NMH will work but you need to have the brush on charge constantly.
    Why not, when you can get cheap 2000mAh NMH battery? See Note2.
    You can buy cheap AA 800mAh NiCad at Harbor Fright, www harborfreight com.

6. Normal AA has no tabs for soldering. You can add your own.
Battery is sensitive to heat, be careful.
Here's how:
    Charge the battery first so that you can test after you finish repairing.
    Add tape to the positive end, around the positive protruding tab, but not the positive pole tab itself. The side around the tab may have metal which is negative pole!!! You may short the battery by accident. Taping prevents this.
    File/sand the positive tab rough and shiny, or when it shows copper. Do the same on the negative pole.
    With a 100W-150W iron, solder a bare wire (24-18 gauge) to the poles of the battery. Or you can pull the flat soldering tabs out from the old battery and reuse them.
    How to solder it to battery:
      Wet the soldering iron tip (melt very small amount of solder on it.) The melting solder on the iron helps to transfers heat fast.
Add solder to the battery pole with hot iron. When solder melts, remove iron, fast. Keep it under 10 seconds. Or let the battery cool down and do it again.
Now add solder to the wire as well.
Put the two together and add solder. The solders on the wire and battery melt together quickly. This helps to limit hot iron contact to less than 5 seconds most of the time.
Tape the contact wires for now.
Cut the contact wires to appropriate length when you put it in the battery cavity. (Length should slightly overlap the pins from the circuit board, to help soldering and mechanical strength.)

7. You need to clean out the battery cavity of the handle as much as possible (rid of the epoxy glue). It is a tight fit. Clean much more at both ends of the battery cavity, for easy slide-in of the battery.

8. Solder all other pins first.
Keep the battery tabs taped. Battery tabs are to be soldered last.

9. After all done and tested, THEN glue the battery in place.
Tip: Can screw the brush assembly to 1/2 of handle for testing.

10. Wait over night; allow vapor from glue to dissipate, before gluing the 2-halves back. (It would then be airtight trapping all vapors.)
------------------------------------------------------------
Note1:
The circuit board is 2-copper-layer type with through holes. That means the hole is copper plated in the inside wall.
Difficult to desolder and clean out solder. You may damage the copper trace or the board instead.

Note2:
NiCad has much lower internal resistance. That is, the voltage can remain flat for prolong operation (maintaining constant voltage).
NMH, though has much higher capacity, the voltage slopes down as it depletes.
Furthermore, the operational voltage of NiCad is higher, at 1.25V, compared to 1.20V of NMH.
The difference is as high as 0.1V using 2 batteries.
The circuit is designed for a flat voltage at 1.25Vx2=2.50V. If it falls below that, the circuit 'thinks' it needs charging. It blinks or may even refuse to work.
You can overcharge the NMH, to higher initial full-charge voltage beyond the normal 2.40V. It fools the circuit that the voltage is high enough. That is why you need to keep NMH always on charge, if you use it instead of NiCad.
It is not the battery's fault. It is the design that specifically to use NiCad.

[bluescrubby]

Caisson, thanks so much for your reply! I'm really happy that you were able to repair three machines with the info here. The steps you include are really thorough, and would merit an instructable of your own if you feel like taking pictures to illustrate the process. Thanks!!

[dlsiegel]

I've been encountering a problem with my 5000 series since I dropped it a few days ago. It will no longer run for the full brushing cycle, cutting off after two or three of the 30 second intervals. I've placed it on the charger and it appears to charge fine, so I'm wondering if this is a battery problem worth opening it up for, or if it is something else altogether. Does anyone have any ideas or suggestions? Thanks in advance.

[dubyayoung]

Great instructions on removing the battery!
That being said, when I removed the guts to my handle I found that there was some corrosion on the bottom of the circuit board. The battery was fine, no corrosion showing on it, and there was no apparent moisture inside. I brushed off the corrosion, and the circuit board appeared to be in very bad shape (see photos).
I contacted customer service to see if it were possible to get a new board, and it is not. And since this unit is out of warranty they weren't going to do anything for me but offer a 15% discount off of a new one.
After complaining a while, and one escalation, they actually agreed to send me a whole new handle!

[bluescrubby]

Good job!

[dubyayoung]

By the way, this is from an HX7500, in case anyone was wondering. Forgot that little detail.

[holykal]

First off thanks to bluescrubby for starting this Instructable. I know it's a couple of years old but I just read it so maybe someone else will get some good from this. After I cracked my 5000 series open, I measured the batteries and they were fully charged! I had to desolder the + terminal to remove the pack from the circuit, let it set for awhile then reattached the + terminal and the unit started flashing like it needed recharged. I figured this was a normal part of the subroutine so I placed it on the charger overnight until it quit flashing and now gives a solid green light. It has been working normal for over a week now. I am beginning to believe the built in obsolescence theory. The batteries are always attached so there is no way to reset the processor (mine has a Zilog Z8). Maybe it's just a fluke but I think that's why one reader saw a flash then his unit started working again. He probably just shorted power to ground creating a reset.

[WMUNN]

Great thread! Hope I can add some info and get a question answered.

I have a HX7500 Sonicare. I replaced the single sub A battery with an exact replacement NICd. Like everyone says a pain, but doable. (I worked as an electronic tech for quite some time, so not a newbie :-)

After replacing the battery and giving it a long time to recharge, it seems to run for a good many brushing cycles off the charger. (I always fully charged, then took it off the charger stand until the batteries were very low even though Philips says to leave constantly on charger.)

My HX7500 has the multi-LED row that is supposed to show battery charge level. However, no matter how long I leave it on the charger, when I remove it from the stand after 1-3 brushings it goes directly to the 1 amber LED "low charge" level. If I ignore this I will continue to get a large number of brushings. So it looks like the charge indicator really isn't measuring the battery, but maybe counting brushings. This seems likely since I have also read somewhere about the brush having a "learn mode" although I can't find that info now.

On this model, if I put it on the stand and hold down the ON/OFF button for a couple seconds it will toggle between emitting a single or a double beep. This is different than the sensitivity/ramp up mode which is on a second button on my model. I wonder if this could be putting the unit into or out of a learn mode? If so, what are the details of making it learn?

Also, inside the HX7500, there is a RESET pad. It is two adjacent solder pads meant to be shorted. I'm familiar with these from other devices and it would appear to be a manual processor reset. That did not solve the problem either.

I've tried multiple combinations of settings and charge cycles, but never seem to get the indicator LEDs to show brushings left.

Since the unit comes from the factory showing a relatively accurate reading I imagine they had another way of setting the unit.

BTW, I ordered three replacement batteries (Sanyo KR-1500AUL) from www.batterystation.com for $19 delivered by Priority Mail. They do have standard 1/4" solder tabs, so I had to add a short length of bare wire to connect to the 7500 circuit board.

Cheers!
 

[50_Oama]

Thanks to all, fixed my model e9800:

CHOMOT: Excellent tip on how to open the case. "Rock back and forth" is the key! Takes some patience, but once the o-ring seal is cracked, it slides out easily!

holykal: Thanks for mentioning the processor reset. Since none of my LEDs were lit, my symptoms sure smelled like a confused CPU to me (and not battery-related).

WMUN: Thanks for mentioning the reset pad. Since I didn't know which pads might reset the processor, I took a chance and used my screwdriver to short various pads that were on the circuit board ("below" the battery, if handle held w/brush-side up). After about 6 seconds of trying the possible combinations, a press of the on-off switch resulted in one of the LEDs going on. It was like getting a new pony for Christmas. It recharged normally thereafter.


Summary:

1) e9800 seemed "dead"...LEDs would not illuminate no matter how long it was left in the charger.

2) Use rocking motion (not twisting) to easily access the "guts" of the handle.

3) Reset the CPU by removing power via short.

4) If none of your LEDs illuminate, it might be a glitch that is not related to failed batteries.


Boo-boo confessions, if you are interested:

a) Removed the rubberized portion of the handle to see if there was obvious access points underneath. Don't bother. See CHOMOT post instead.

b) Since the unit seemed "dead" (and not "limping"), I tried the Fonzi technique of giving the handle a few solid raps against the counter. If there are cold solder joints, or inadvertent shorts caused by residue build-up, sometimes the Fonzi trick works wonders. 'Course, I usually try this as a last ditch effort, I should have consulted Instructables first!

Thanks again everyone!

[bluescrubby]

@WMUNN, great input, and thanks. 

[bitor]

***Another Way To Replace Your Batteries***

First off, Thank you for the direction and commentary on this subject.
While on vacation I had dropped my older sonicare and after that it did not work.
So, I decided to open it up like I normally do on things in general. This was before I came across these directions. I cut along the seam and opened it up. To my surprise two double AA batteries in some epoxy. I tested one and it read ok, but the other one was dead. So, I knew I had another older sonicare brush that I acquired because of my friend getting a newer one and this older one I thought would be a back up when my previous one went bad sometime in in the future. I knew it had worked before, but had not been charged for a 1 year or so.

When in my closet and put it on the charger..the light went on and the next day I decided to us it on  my teeth. Guess what? It did not work. The light was on but nobody was home.
Tried to reset the the sonicare, but this did not either have the reset built in or maybe the reset event is different for the older ones. So I looked at both of them and thought I'm going to replace the batteries in this unit because the were both the same size I decided to go about the replacement of the batteries a little bit different. 

The method here is good, but this to me after opening the first one did not seem piratical to open the whole brush to get at the batteries. To destructive for me. I decided to take measurements on the first one to calculate the exact spot where the batteries are and with the one that was not open, came from behind from the bottom up and cut the back side open at the top of the batteries and bottom. These two cuts would be parallel with the bottom of the sonicare base.
Next I cut one perpendicular and down the center between the two prevous cuts connecting them with this one cut. (Like an I beem)
This cut was made because of the epoxy that encased the batteries for easier removal of the outer case. Which would give me more sight on how to remove the batteries.
Next and very last I went across the mfg. seams to connect the first cuts.
So the whole cut was like a box with a single cut down the middle of the box with only the battery section half of the sonicare back side removed.

Then I took a screw driver's flat edge and placed it in between the second middle cut and twisted to remove the outer shell of the sonicare battery case.
It popped right off on one side and the other popped off after wedging the flat head of the screw driver between the outer sonicare case and the epoxy. Always keep in mind to try and hold the batteries so as not to stress the  joints on the PCB board.

Now what I had left was the batteries and the epoxy that had not all the way been cut throw on the first cuts.
My biggest concern here was not to break the connection from the PCB board. So I cut throw the rest of the epoxy so the only thing left holding the epoxy and batteries were the connectors from the PCB board to the ends of the batteries. This left me room to gently pull the ends of the batteries closes to the bottom out enough to get a small flat head screw drive in for prying.
I then simply place a small flat head screw driver in between the contact spot metal weld points of the batter and rotated/twisted the end until the spot metal area on the tops of the battery released. Now I could pull out the two batteries and replace them. Note that you only have to break the spot weld on the batteries' top closes to the sonicare button. The bottom doesn't need the spot metal to be removed in order for you to remove the batteries form the sonicare compartment you have made.

I know this is a lot of info and pictures would cut down this to half or more. But this I found to be a much better solution then slicing the whole sonicare brush in half. You will now have to do some soldering and could make so you could put springs in to just pop in and out the batteries when they go bad.
I just decided to solder wires to the batteries and put a rubber band around it for now. I will do something to seal the PCB board from the outside so water and etc. will not get in. I just did this so everything works great on it now. I've charged it and it works great.
The reason why the second older sonicare brush did not work even throw the light came on but would not charge is because one of the batteries leaked over time. That's it. As far as the first one I dropped on vacation, I don't know. Maybe it damaged something inside.

REMEMBER this is for the older sonicare brushes and not the newer ones.
Not to say this would not work for the newer ones.

I hope this gives a different angle on how to replace the batteries and inspires others to fix theirs this way. Less destructive and still keeps the integrity of the sonicare brush in tact.

Best regards

[slogreen]

@bitor. I followed your instructions to remove the batteries on my Sonicare that was no longer working. I have a nice clean cut and was able to access the battery compartment and remove the 2 AA NiCads. I tested them and discovered that they are charged. I tried two other NiCds, but it still doesn't work. Is there some sort of reset button on this model?

[jeffreyi]

I went away for two weeks and left the sonicare unplugged. Returned home, plugged it in...not charging (no green light). Charger very slightly warm, so the power seems OK. Advice?? Thanks.

[suzeliz]

Jeffrey - I just had the same experience - was on vacation for two weeks and when I came back my sonicare won't charge. Did you figure this out? Thanks, Susan

[free.self]

How to open the 9000 seriers brush? I can't find a way in.

[krush_groove]

Great instructions! These were a great help, I had to look at the picture to figure out which pin is positive when putting the new batteries in, it's a good idea to note this when taking the old batteries out. 2300mAh Ni-MH batteries are charging up pretty well so far and I used a hot glue gun to secure the batteries and seal the sides up. And if you can, recycle the old batteries :)

[stress_guy_53-30]

For those who would rather let someone else do the dirty work, I found a guy on eBay who fixed my classic 4700 handle in a week (first class mail both ways) for $25. It works as good as new, and with three old brush-heads that would not fit the new handles, I took a chance and I am glad I did. Look for "Sonic Repair" -- I even gave him my first-generation handle for spare parts, and he overpaid me for the first-class postage. Great e-business person!

[JerryI]

Since the old-style Sonicare runs on about 3V DC, would it be feasible to snip the battery leads and tap a ~3V DC wall charger cord in at the appropriate points; then forget about recharging. Plug the wallcharger in, all the time or whenever you want to use the toothbrush. I would appreciate comment from someone who has already torn one of these apart. I haven't done so yet, but mine is to the point where I only get 4-5 brush cycles without recharging. I wouldn't mind a corded toothbrush if I could save $50 bucks or so.

[wizrd4824]

Never scrape a board. Use isopropyl alcohol and a small brush (medium bristles). The foreign debris and corrosion should come off.

[wizrd4824]

If you use a little flux and some desoldering braid, this step will be a breeze. It will also avoid overheating the PCB and damaging the traces and pads.

[grooveman]

well, I blew it... Word of warning: Be careful when removing the solder from the 8 identified pins... a couple pins heated up too much on me, and wound up coming out of the plastic which held them, and somehow one of the copper wires from the coil around the electromagnet came off as well. There was no play in the wire what-so-ever, so I couldn't solder them together. Looks like I'm out a toothbrush. I think this would have been avoided had I been more patient. I really just needed another hand... I recommend at least 3. Also, my soldering pencil was not hot enough to remove the wire soldered to the battery, might need a soldering gun, or more powerful soldering iron.

[chamunks]

You could allways epoxy it back into the case. But good luck getting the pins back out again.

[spiderx]

It works just like a speaker does, except this coil is the "speaker coil" and the head is the permanent magnet. Apply a voltage to the coil, and it repels the magnet. Apply the opposite voltage, and it attracts the magnet. Since it works the way a speaker does, they decided to call in "sonicare" since all they have to do is push a 700hz signal through the coil... actually, its a 666(and 2/3)hz signal, to get 40,000 cycles a minute

[cleanme]

I replaced the 700 mAh NiCad batteries in my sonicare with 2600mAh NimH batteries - ran the unit with a meter and watched charge cycles etc. Works perfect! Unit trickle charges within acceptable limits for NimH and even registers a full charge. In my case above, it logically took about 3x longer to reach a full charge, but the unit will also run 3x longer from a full charge then vs. the NiCad. Cheap and plentiful to get NimH AA batteries retail. Requires de-soldering of about 6 points - use a low temp solder iron, solder sucker and appropriate skills. $12 in batteries, 3 hours effort - saves me wasting a good unit that lasts three times longer run time and will be better suited charge longevity over NiCad. Pays to be a geek.

[guetch]

Repaired the first one without problems. I use an Arborite scraper ground down to fit the groove of the housing. Now with the second one I was maybe a bit hasty with the solder braid succer and shorted a transistor.AERA surface mount but can't fine a replacement with this #. So, my advice to anyone is, cut the positive lead to the battery under the board before desoldering. Any advice on the repl. trans. would be appreciated. Thanks Armin

[Red-Headed Woodpecker]

I successfully replaced the batteries in my Sonicare. I used a utility knife to cut the halves apart. The case is thicker on either side near the switch. You can cut a depth of about 1/8 inch alone each side. Be careful and don't cut too deep on the bottom. Take the circuit board off by unsoldering 8 points. The batteries are glued in very tight. I slit the outer wrapping of the batteries and was able to get the batteries out then removed enough of the wrapping to get the new batteries in. I used RTV silicone (get it at an auto parts store) to secure the new batteries in place. After doing the repair and verifying it worked, I used super glue gel to put the halves together. BTW, the original batteries lasted about 6 years, and I leave it in the charger all the time when I'm not using it.

[dgmoose]

I was able to get the sonicare opened with a utility knife, but instead of replacing the batteries, I used a battery resurrection technique that I purchased on eBay for $12.95. http://stores.ebay.com/Battery-Resurrection
The sonicare had been dead but now is alive, hallelujah!

[0.775volts]

if you can get it working again, electric toothbrushes can make one very good lock pick, i'm sure you can find directions online, but just looking at an "electronic lock-pick" will give you the basic idea. keep in mind however that this may not be legal in your area.

[BorisTheSpider]

Has anyone seen any decent instructions on this. None on Instructables. Maybe someone is up to the task?

[darbytomusa]

Eureka! I found a way to remove the insides(battery etc.) from a Sonicare Elite 7300. With the help of others on line, I knew it would come apart. I tried various other non-destructive methods and then Eureka! With the toothbrush assy removed I stuck a painters roller brush extension, (a broom handle etc. will work) about 4 ft. long, into the cavity in the top, tapped it lightly with a rubber mallet. Then I put the wooden handle in a vise with the battery just showing on top of the vise. The other end of the handle is best positioned if it is pressing against the floor (for stability). Now you can wiggle the outer case vigorously upward with two hands and it will come up with relative ease and no damage to anything. Be aware there is only one battery in it..There are two solder tabs, easily desoldered and not epoxyed. apparently it is a 1.5 volt battery,no markings but another on line user replaced it with a AAA battery. Probably works fine but just shorter run duration. He jut increased the diameter to fit tight. I'm going to Batteries Plus tomorrow to try for the correct battery. If somebody has the battery spec's or # would appreciate

[darbytomusa]

To follow up on the battery I got an exact replacement at Batteries Plus,Lake Zurich,Il. Part #NUH4/5A-1, 1.2v 4/5A 1700MAH NIMH . Cost $4.29, They even tacked on the leads.(Tack Welded) I put the + lead in first with the battery at a 45 angle, then brought the other end down while feeding in the - lead. Take your time, clean the lead holes so the leads slide in easily. I used my old reliable 37 watt iron. Don't over heat board. It snaps together easily

[bibbli]

For anyone interested in prying open and trying to install a new set of ni-cad rechargeable batteries in an older Sonicare Advanced model, I highly recommend against it. Both batteries are surrounded by an epoxy that makes it pretty much impossible to remove them.

[regnadkcin]

pretty much impossible? bah, aint nuttin bilt wut cant be unbilt with a dremel....or some low grade explosives....he he he he

[bluescrubby]

However, the batteries are epoxied in while still in a plastic wrapper--the white wrapper is easy to see in the pictures. Cut the wrapper open, remove the batteries, and you have a nice indentation to place your new batteries in! Or you can remove the epoxy after the batteries with a dremel tool and put new epoxy in when you put your new batteries in.