Electronics > Repair
Repair of Bosch induction cooktop touch controls
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.
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