Why doesn't the Num Lock LED light up on my Keysight E4990A keyboard?
- SSue Carroll DDSSep 13, 2025
If the LED on the keyboard of your Keysight Measuring Instruments unit doesn't light up when you press the Num Lock key, there might be an issue with the A60 CPU module. Before replacing the A60 CPU module, verify that all connections to it are secure and normal, without any disconnections or loose connections.














