/4 Keyboard only left half works. Right half not

[globeron]

If I remember correctly the whole keyboard worked before, but now only the left half works

I do not see loose contacts.

 

 

[AwkwardPotato]

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.

[globeron]

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.

[globeron]

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).