globeron Posted December 14, 2020 Share Posted December 14, 2020 If I remember correctly the whole keyboard worked before, but now only the left half works I do not see loose contacts. Quote Link to comment Share on other sites More sharing options...
AwkwardPotato Posted December 15, 2020 Share Posted December 15, 2020 Aside from the keyboard itself being damaged, the only thing I can see causing this is a part-dead 9901. If you have a multimeter: check the resistance between pins 6-9 of the 9901 and ground, and then the resistance between those same pins and +5V to see if anything's shorted. Then check if those same pins are connected to any of the contacts on the keyboard. 2 Quote Link to comment Share on other sites More sharing options...
globeron Posted December 19, 2020 Author Share Posted December 19, 2020 On 12/15/2020 at 10:34 AM, AwkwardPotato said: Aside from the keyboard itself being damaged, the only thing I can see causing this is a part-dead 9901. If you have a multimeter: check the resistance between pins 6-9 of the 9901 and ground, and then the resistance between those same pins and +5V to see if anything's shorted. Then check if those same pins are connected to any of the contacts on the keyboard. Okay. I will check that. Thanks for the guidance. Quote Link to comment Share on other sites More sharing options...
globeron Posted December 19, 2020 Author Share Posted December 19, 2020 The /4 keyboard seems to be working again for now. I reseated all the socketted chips, not sure if it has to do with that. (9901 NL is not socketted). Quote Link to comment Share on other sites More sharing options...
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