I am using NI-USB 6289. I notice something weird on the +5 V terminal. When the +5 V terminal is not connected to an external load, the voltage between the +5 V terminal and a ground terminal is +5 V. Nonetheless, when a load (e.g., a 100 kOhm resistor) is connected between the +5 V terminal and the ground, the voltage across the +5 and ground drops to ~3.4 V.
I am not sure what is going on. The DAQ is powered by a cable and also connected to a PC. So, I assume that the current drawn from either a power cord or USB should be sufficient. Can someone please help me with this problem?
As per the device specifications, 100k load is totally fine, it would be worth checking the fuse.
Is this issue consistent across all 4 pins (2 on each connector)?
I believe the USB version is externally powered, could you check if the power supply is good?
Thank you Santhosh. Unfortunately, I have the NI USB-6289 with the screw terminal pinout. Therefore, only one +5 V terminal is available.
As per this image, screw terminal 98 is connected to the fused +5V, were you able to check the Fuses and replace?