Author Topic: Repair of Bosch induction cooktop touch controls  (Read 338 times)

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Offline cozza

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Repair of Bosch induction cooktop touch controls
« on: May 06, 2019, 11:05:25 pm »
At home our Bosch induction cooktop became unresponsive to the power on button, in the last week of it's two year warranty. Fortunately I was able to arrange to be there when the repairman came, and replacement of the display / touch panel solved the immediate problem.

It's not an uncommon fault for one or more of the buttons to stop working or be intermittent in operation, according to the repair person. I asked if I could keep the old board to have a look at it, which was fine, because "no one can fix those mate!"  :-DD

The board is fairly involved and has touch pads, the led displays, a control microcontroller and a sounder. It is made by EGO, and apparently is common to a whole swathe of other European brands, including Gaggenau, Neff, and possibly Smeg as well.

Inspection revealed that the touch pads connect via a resistor into the inputs of HC4053 chips, a triple 2 channel analog multiplexer. There is no external protection for ESD for the conductive pads which sit below the glass cook surface, although the HC4053 has protection internally.

Replacement of the 74HC4053 associated with the power switch restored functionality, so now we have a service spare board should the fault arise again. I also replaced the HC4053 IC associated with element selection, as this had been unreliable for most of the life of the appliance, although not annoying enough to warrant a service callout.

Hopefully this will be of help to other EE's in an out of warranty predicament.


« Last Edit: May 06, 2019, 11:15:12 pm by cozza »
 
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Offline chris_leyson

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Re: Repair of Bosch induction cooktop touch controls
« Reply #1 on: May 06, 2019, 11:24:08 pm »
Quote
It's not an uncommon fault, for one or more of the buttons to stop working or be intermittent in operation, according to the repair person.
not at all surprised because it's designed by engineers who don't give a damn. Well maybe the engineers do give a damn but they have to design to minimum manufacturing cost and not for performance and long term reliability...
« Last Edit: May 06, 2019, 11:37:44 pm by chris_leyson »
 

Offline cozza

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Re: Repair of Bosch induction cooktop touch controls
« Reply #2 on: May 07, 2019, 12:04:54 am »
I'm dreading the day I have to pull out the Bosch wall oven to investigate the similarly (mostly) unresponsive touch controls on that..

It's now out of warranty.

 

Offline cozza

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Re: Repair of Bosch induction cooktop touch controls
« Reply #3 on: May 07, 2019, 12:11:46 am »
As a non warranty replacement of this control board will set you back over $700 NZD, it's compelling to change the $0.88 NZD chip instead.

Farnell / Element14 2445306
 
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Offline james_s

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Re: Repair of Bosch induction cooktop touch controls
« Reply #4 on: May 07, 2019, 05:28:00 am »
Maybe contact some service shops and offer to purchase defective boards. If new ones are that expensive you can sell refurbished boards on ebay for a tidy profit.
 
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