This solution may help to trace and repair a particular QWERTY keys that doesn't work or stop responding
when press. This guide shows the layout of the nokia C3 of each
corresponding QWERTY keys line paths and connection. Before proceeding
to trace of each particular line paths please ensure that the keypad membrane switches is perfectly clean and free from any corrosion and oxidation, the membrane switches will not having a good contact to the keypads cores if it is corroded. All corresponding
membrane switch keypad must be absolutely clean. You may need a new replacement keypad membrane on it if the membrane switches is damaged and unable to pop up back when press.
Each corresponding keys are divided into group of rows and columns. The outer core layer of the keypad are group into rows and the inner core layer are group into columns. Each rows and columns are connected with each other.
The outer core are group from 0 to 7 rows. Each color on the picture indicate where that certain keys are connected to a group of rows.
The
inner core layer are group from 0 to 7 columns. Each color on the
picture indicate where that certain keys are connected to a group of
columns.
The keypad line paths is connected into an EMI-ESD filter chip which is located at the right side of the main PCB board. This chip also get damaged and result to keypad malfunction. The picture below shows also the internal connection of the EMI filter chips from each keypads rows and columns.
Hardware Repair Tips for keypads: If just only one or two to four keys are not working the problem may lies an open or cut connection to it, trace where that certain keys does not work to the particular group of rows or columns it is being connected. You may apply a simple jumper wire on it as an alternative way. If more than five or more keys are not working you may consider that the problem lies on a damaged EMI-ESD filter chip
membrane switch keypad must be absolutely clean. You may need a new replacement keypad membrane on it if the membrane switches is damaged and unable to pop up back when press.
Each corresponding keys are divided into group of rows and columns. The outer core layer of the keypad are group into rows and the inner core layer are group into columns. Each rows and columns are connected with each other.
The Nokia C3 silicone rubber keypads
The outer core are group from 0 to 7 rows. Each color on the picture indicate where that certain keys are connected to a group of rows.
The Outer core connection line paths ( C3 keypad ways )
The Inner core connection line paths ( C3 keypad ways )
Hardware Repair Tips for keypads: If just only one or two to four keys are not working the problem may lies an open or cut connection to it, trace where that certain keys does not work to the particular group of rows or columns it is being connected. You may apply a simple jumper wire on it as an alternative way. If more than five or more keys are not working you may consider that the problem lies on a damaged EMI-ESD filter chip
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