Repair of Bosch induction cooktop touch controls

[scooch]

Hi Domini380.

Also having the same issues with several buttons.  Domini380 can you please post a picture of these copper strips and how attached?
I have been researching this issue for over a year and this seems to make sense!  Thank you.

[cozza]

Hi Domini380,

Thanks for figuring out how the EGO touch system works and what to do when it fails.. that all makes sense now.

The Bosch wall oven has now developed an annoying fault, where once or twice a month it will randomly turn itself off while cooking - no fault code is shown, it just plays the turn off tune and shuts down. Fortunately I'm normally within earshot and hear it abort, but it could end up being a very late meal otherwise! 

There's something to be said for mechanical switches and simmerstats after all.

[benneton]

I will put my 2 cents, if you don't mind. Had similar issue with my De Dietrich induction plate.

What I discovered too that touch panel is responsive with direct capacity change with a simple touch of screwdriver on it. I suspected that either some passive components are weared-off or that glass would have some issue. Tried with some glass that I had from some older plate - it worked. So my conclusion was that there's some issue with the original one's coating from the inside and I was right. I just taped some insulation tape from the inside to separate the touch areas. Worked well after that. My guess it heat damaged it somehow (maybe near placed or too big cookware?). This works for 3 years now (my concern was it won't last due  to simple insulation tape that I've used - thought it would peel-off - it didn't obviously).

For the other Sauter's cooktop, I had similiar issues but that time it was due to some faulty filter caps on the power board. Power supply from the power board to touch panel had some unwanted signals on the 5v and 12v. Maybe it affected multiplexer/mcu work somehow.

Hope this helps.

[digicur]

Hi Benneton,

could you please give us more details about your solution to this touch control issue? You applied small pieces of insulation tape on the back of the glass plate in order to separate each single touch area from the other touch areas? Is that correct?

Thank you
Phil

[benneton]

Hi Phil,

Yes, that's correct. It seems like existing coating "expired".

Sorry for the late reply!

Regards!

P.S. Could be that coating became conductive. Can't imagine any other explanation currently...

The indications that were present on De Dietrich's hob before I applied the tape solution (without particular order):

* Not responsive
* Multiple key pressed error (dashes blinking on the display and beeping)
* Turn off seconds apart from the power on pressed

[Klimfilt]

Hi all, unfortunately i'm writting here with the same problem... I have Bosch PXE675DC1E and first the timer button started to make troubles, but i ignored it because it's not a important key, but now the power button is dead and now this is a big problem. Im out of warranty so when i went to official bosch repair service, they told me that they don't service PCB and when client came to them with problem like this, they just buy new PCB... Yeah, 150 euros per 2 years, and after 7 years i will be paid the same amount of the induction hob, but this time will be only in boards... It's ridiculous and pity for Bosch company...

So now, how to resolve the problem. I saw 3 different methods to resolve problem. 1) to change the 74HC4053 chip , which accordingly to cell phone service technig would not help, because either the chip is working or not (i saw the post by Cozza) but if i tell him to do, he will do it after all. 2) to add copper foil on buttons (sensors) after i remove the glass, like Domini380 did and 3) to use isulation tape and put it on the back ot the glass, between sensors and glass, like Benneton sugest. So 2) and 3) method are close by same way, because both give advantage to increase touching surface and to make it more solid. Today we opened the hob and without the glas we touched the sensors directley and they worked, after that we used different cover for sensors (simple thin glass) and it worked just fine. But there is a logic in that, the chips to be gone because of the heat. And last one, guys from official Bosch service gave me 3 boards for free with buttons (sensors) and chips. I'm not sure that they are from the exact same hob, but visually they are the same (some have 2 large zons, other have more buttons) but in general they are the same.
So is it a good idea to use other HC4053 chips (not the one behind power button) and to install them on my board, or to order new ones from Farnell ? And will this even work, i mean to change chips?
Or to try to make touching area stronger?

P.S. Benneton do you have pics of your work ? And if not, can you tell where exacly did you put isulation tape on the back of the glass? Where the sensors make contact with the glass (looking my glass on the back, the sensors made their own nests), you mean to add tape there or ? I would be very greatfull if you add 1-2 pics of your job.

[benneton]

Hi @Klimfilt.

Insulation is not above the sensors, but surrounding the spots. Just follow the pattern that was already there. I did take a picture from above (moment ago) and remembered that I also removed remains of old coating, too. See attached.

Will see to open it and make some pictures from the inside.

[cozza]

Hi I would follow the advice of Domini380, as it's specific to the type of controller fitted to your cooktop. I cannot say whether the advice regarding adding the layer of insulation is relevant as it is a different type of hob.

I would try adding the copper foil strips to the non responsive buttons first and see if that solves the problem. If nothing improves, then replace the 4053 chip associated with the button. The copper strip on the button would connect via a piece of thin wire to the 4k7 resistor which feed into the 4053 input.

Let us know how you get on, I am curious.

[cozza]

The problem with the Bosch touch sensors as Domini380 explained it is the connection between the grey conductive stuff on the button, which connects through a heat stake to a PCB pad, to the 4k7 resistor getting weak due to thermal cycling.

The easiest button to verify this with is the power button (no illuminated legend to cut around). Cut a square of foil the size of the top of the button (and leave attached a thin strip of copper foil like a wire to connect to the resistor).

Glue the square to the power button, solder the thin strip of foil to the 4k7 resistor ( the button side, not the chip side) and see if that solves the problem.

[Klimfilt]

Hi all and thanks for fast responses. I'm sorry, but i'm not good at electronics (i'm an accountant...) but i like to resolve problems, not to be a consumer guy... So, please forgive me, but i didn't understand all that i should do . I'm attaching pics of my PCB, and what i did today and the how started to work (well not all sensors, but 85% of them are as new). When i removed the glass i noticed that the PCB lay on a black plastic base. This base is hooked to large metal square by 2 pinchs. When i touch the PCB it seemed to be very unstable and shakes a lot. So my first guess was that there is a "big" distance between the sensors and the glass. So i add some pieces of cardboard. After that PCB become a lit a bit stable and i installed the glass and when i tried the power sensor, voala it wokrs just like new one... But unfortunetley my joy was short when i figure out that not all sensors works. With this "invention", sensors marked with "1", "2", "5.5", "9", "boost" and two sensors for the large cook zone don't work. I know this is not a serious job and it's dangerous but it work and it's a some kind of a starting point. I will atach pics of my hob and what i did, but i didn't understand quite good the part with copper foil and where to put it. On top of the sensor (between the glass and surface of the sensor) or to remove the sensor from the PCB and to add it over the PCB and after that to install again the sensor on the PCB ? And what about the wire, and which resistor to connect with it? Sorry once again, i just need to be explained it like for a newbie or even a full noob with electronics. With 2-3 pics of the exactly what it should be done, may be it will be easy to understand. I will be very greatfull.

IMG1 - This is my "working" hob after my "invention".
IMG2 - This is the cover underneath the glass. Im not sure but i've read somewhere that this is some kind of silicium. @Benneton could you please tell me exact where i shoud add insulation. Can you point it on my pic ?
IMG3 - This is what i did...
IMG4 - How it looks after asembly
IMG5 - And it works ... Partly...

P.S. All sensors are working when i barely touch them directly (i mean when the glass is removed, like picture 5)

[Crocodiledundee]

Hi all,

I opened up my induction cooker and found that one of the soft black pads on the touch pad Board has come detached which explains why one of the hobs has no response when trying to turn it on. Can anyone tell me what adhesive I should be using to glue the soft black foam back onto the board? From looking at it it looks like they used 3 dots of some kind of red adhesive. Please kindly advise.

[Klimfilt]

Hi again and thanks for advice. So if i'm undestand it right, i have to put a copper square foil on top of the sensor (button). Second i have to solder a very thin copper strip, the one side to the copper square and the other side of the stripe have to be solder to the one (or two, even both may be?) of the corrners which are underneath the sensor. For this one i have to remove the sensor from PCB and solder the thin stripe. Right? Not to the opposite side of the PCB where there is only chips. Am i on a right way ? And if this didn't work, to re-solder the chip ?

[Crocodiledundee]

Hi all,

Update, I used some 3m spray glue which is approved for conductivity and reattached the conductive foam to the chip board. This seemed to have done the job and upon testing with a screw driver as well as a my finger the button worked fine and well. However, when I put the glass panel back on and tried to use the aforementioned button there is no reaction. I checked the conductive gel on the underside of the glass and it is fine without distortion or damage. I am absolutely miffed as to why as soon as the glass panel goes back on the button no longer works. Any ideas what the problem could be?

Ps the cooker has 4 hobs and the faulty button is the button that activate the main/big hob.

[benneton]

Coating became conductive, I have no other explanation. It is what's with my hob. If it is conductive, one sensor is giving electrons (or stealing) from other sensor/s (case with capacitive ssnsors only, not optical). Just add some regular sellotape to check if that is the case. Put the glass back and test it. If that would help, find some fire resistant tape. In my case I have ceramic icons printed on the glass. Since your hob has led icons, I think that my solution with insulation tape wouldn't work because it is not transparent. Like I said, try only with sellotape. If that would be the solution, use something that will not catch fire (or melt). So: sellotape over the glass where sensors are. I cannot fiddle with the disassembly, sorry - all is sealed perfectly with silicone around. But no need actually to do that. Just imagine conductive coating... Add something that is not conductive over it.

[cozza]

Hi sorry for the late response. I'm at home in lock down, the hob controller is at my workshop so I can't confirm the soldering points.

You don't need to remove the sensor pads at all. It will be a case of sticking a strip of copper foil to the top of the "button"  and soldering the other end to the corresponding resistor for each button - on the top side of the board. I'd try a thin (2 or 3 mm) strip first rather than a full square the size of the button.

Start with a thin strip and see if it's sensitive enough.

Note I have not tried this, I'm just going on the previous post.

If you hold the board up to the light you'll see a clear circle of fibreglass with a pad in the middle next to each touch sensor, this is the point where the plastic touch button connects to the circuit board trace / resistor. Looking at the photos it may be a 10K resistor for the power button (103) and 4k7 resistors for the other buttons (472).

Using a multimeter you should get 0 ohms between the pad in the circle and the end of the resistor the foil strip will need to be soldered to.

[ievosabo]

Hi, after reading all this, I decided to fix the cooktop one more time
Short flashback: my previous step was using silver conductive glue to fix the covering of the "gray" sensors. I would say it was not a great success, but at least 90% of sensor buttons were reanimated.
I used a Kapton tape and thin copper wire this time. So, I soldered to every button's resistor the thin copper wire. The wire got the form of a not closed-loop rectangle over the sensors. These tiny "antennas" are covered by Kapton film to keep them intact.
Hence, I have every sensor with an individual wire over it and every sensor isolated from a fiberglass top by Kapton tape. Every button works precisely and has no problem whatsoever. I must test it under thermal stress, using all induction areas simultaneously when cooking a lot.

Thanks for advising the engineers. It looks like you are right. There are two major issues/things: 1. make sure sensors are appropriately isolated (I used a Kapton tape in my case) 2. improve/fix sensitivity by duplicating a sensor area with an extra copper layer (I used thin wire, as do not have dedicated copper tape recommended above) but it works and the idea the same.

Did nothing with the ICs.

I hope it helps you with the repair work.

[scooch]

Hi.  Thanks so much for the information and hoping to fix our cooktop and we keep losing one button after another.

I think I understand your method but any chance you could post a picture?
It would be greatly appreciated!

[scooch]

Klimfit.  I have the exact same problem and same type of cooktop.  Elevating the control panel helped with some buttons.
It seems that the black silicone substance on the glass may have lost its conductivity and/or shrunk.
Wondering if you ever resolved your issues?  Thanks.

[buhini]

Hi, first of all introduce myself because I'm new to this forum.
 My name is Rafa and I am fond of electronics, my job is a vehicle mechanic.
The second thing to apologize for the bad translation of google translator, since I do not speak English.
I wanted to show you my experience with my bosch induction hob, the same one shown in this thread.
The same thing happened to me as to the rest of those affected, loss of touch on the buttons, at first I didn't mind losing the 9 or 0, but when the power stopped working I couldn't stand trying to repair it.
My first option before discovering the forum was to resolder the most accessible resistors and capacitors on the entire board, this did not solve anything.
The next thing was to fit the electronic plate with cardboard below to raise the point of contact with the glass, but it didn't work either, it made error sounds.
So I found this forum and read it in its entirety, I ordered the 4053 chips on aliexpress and as soon as they arrived I changed the first one, the one corresponding to the power and lock button, tell you that I noticed a little more touch without the glass, but with the glass on did not work.
So I changed the 4053 chip corresponding to the most affected buttons, the ones that had to be pressed in the lower corner to be activated, in my case it was number 9, I put a new chip and before trying it I decided to resolve it with quality flux and Tin the rest of the 4053 chips, all of the ones on the back plate (be careful! Only resolder).
And it turned out positive! All the buttons on the panel revived like the first day with the glass on.
I have cooked and everything is correct, but I realized that suddenly the 0 button had failed again together with the 9 button, and the turn on button again becomes less sensitive and you have to press it a little harder, so I will disassemble again again and I will change the 4053 chip that affects those buttons and I will try again.
So I recommend not putting cardboard under the plate, since the problem is electronic and not due to the silicone of the glass.


Hola, lo primero presentarme porque soy nuevo en este foro.
 Me llamo Rafa y soy aficionado a la electronica, mi trabajo es mecanico de vehiculos.
Lo segundo pedir perdon por la mala traduccion de google traductor, ya que no hablo ingles.
Queria enseñarles mi expereciencia con mi placa de induccion bosch, la misma que se muestra en este hilo.
Me ha ocurrido lo mismo que al resto de los afectados, perdida de tacto en los botones, al principio no me importaba perder el 9, o el 0, pero cuando dejo de funcionar el power ya no pude aguantar a intentar repararla.
Mi primera opcion antes de descubrir el foro fue resoldar las resistencias y condensadores mas accesibles de toda la placa, esto no soluciono nada.
Lo siguiente fue calzar con carton por debajo la placa electronica para elevar el punto de contacto con el cristal, pero tampoco funcionaba, emitia sonidos de error.
Asi que encontre este foro y lo lei entero, pedi los chips  4053 en aliexpress y en cuanto llegaron  cambie el primero, el correspondiente al boton de encender y bloqueo, deciros que note un poco mas de tacto sin el cristal, pero con el cristal puesto no funcionaba.
Asi que cambie el chip 4053 correspondiente a los botones mas afectados, los que tenia que apretar la esquina inferior para ser activados, en mi caso era el numero 9, puse un chip nuevo y antes de probarlo me decidi a resoldar con flux de calidad y estaño el resto de chips 4053, todos los de la placa trasera (ojo!!, solo resoldar).
Y resulto positivo!!, todos los botones de la placa resucitaron como el primer dia  con el cristal puesto.
He cocinado y todo correcto, pero me di cuenta que de repente el boton 0 habia vuelto a fallar junto al boton 9, y el boton de encender de nuevo vuelve a ser menos sensible y hay que apretarlo un poco mas fuerte, asi que desmontare de nuevo y volvere a cambiar el chip 4053 que afecta a esos botones y volvere a probar.
Asi que recomiendo no poner carton debajo de la placa, ya que el problema es electronico y no por la silicona del cristal.

[buhini]

In the end I decided to change the control panel because I repaired the contact buttons three times by changing the chips, and it lasted working well for a couple of hours, then they failed again, I bought the control panel directly from Bosch, 179 euros, and it works perfectly, they have modified some things and removed others.

[Otso]

Thank you ievosabo and everybody! With your aid I was able to fix this on my hob.

I've only tried the 7, which was broken, and it now works perfectly! I'll go on and the the same for the remaining failing buttons (about 4 more).

I took a strand from multistranded ethernet cable and soldered it to the back where the button is attached. I also tried soldering to the resistor, but this one was too difficult for me to reach, and I managed to melt the button slightly when I tried.

Beware though, that you might mistakenly pull out the original solder for the pad, which I did at least partially. I first tried soldering a thicker wire, from a single stranded ehternet cable. It was too thick and heavy, and difficult to attach, and I managed to pull out the solder with that one.

Here's pictures of the front and back.

[Otso]

I ended up repairing 9 buttons. Now it's good as new again! Thank you once for the advice. I would never had figured out this myself. And no components needed to be replaced.

In case anyone is wondering which resistor to attach to, it's the tiny resistors next to the button. As has been said in the thread, to make sure your are connecting to the correct resistor on the correct side, measure that the resistance is close to 0 Ohm between the resistor and the tiny pad on the back to which the button is connected.

Here's a photo showing some of the resistors encircled with red, and also showing one of the buttons I fixed.

[ELBUTMAN]

Hi all, I could also repair my faulty touch button using the suggestions from Domini380. In my case I could solder the copper foil directly to the metal circle in the board on the base of the button, that wasn't completely covered by the pad in the edges. It works perfectly now!  Thanks again!

MAC

[optic]

Just repaired with your help. Only thin wire, without tape. Soldered from bottom, much easier. Pictures attached.

[Swake]

Another win!
Given the number of cooktops that fail this clearly falls in the category of the manufacturing issues.