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crwdns2933797:0Thomas Widmaiercrwdnd2933797:0crwdne2933797:0
crwdns2936043:0crwdne2936043:0 crwdns2933505:0crwdne2933505:0 Thomas Widmaier
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| + | [title] Measure |
|---|---|
| + | [* violet] This is the section of the pushbuttons. Each of them, when pressed, is shorting to ground one connection in a resistor chain. This basically is a variable resistor to the microcontroller on the other end of the ribbon cable. The microcontroller measures the resistance and decides which value means which keypress. |
| + | [* violet] The problem comes when there is another resistance appearing due to dirt or other reasons. Then the whole circuit can behave as if random keys are pressed. |
| + | [* red] Remove ribbon cable |
| + | [* light_blue] Measure resistance to ground at this point. Should be OL (open) |
| + | [* black] If not, measure resistance across pushbuttons. Search for lowest resistance. This is the place you want to replce the pushbutton |
| + | [* orange] The resistances from left to right are 1k, 1k2, 1k8, 1k8, 2k7, 4k7 |
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