I want to test my IC's without using the nixietubes first. whenever i put the inputs on how i want them i dont get the output i want. If all my inputs are set on low which i do with a microcontroller (nucleo f303k8) the output which is port 16 has a voltage of around 1.3 V while port 15 (which should have a high output when only input A is high) has a output voltage of around 1.7V.

Does anybody have an idea what i am doing wrong here?

 

Post your circuit diagram.

 

Your post is not very clear. You say " If all my inputs are set on low " it seems to be a contradiction. On normally means a high level. Off normally means a low level. For your KD1551D1 which seems to have the same datasheet a a 7441 a logic low is anything less than 0.8 volts and a logic high is between 2.0 volts and 5 volts. The outputs on the KD1551D1 are active low (They are open collector outputs which means thy need pull up resistors if not connected to the cathode of a nixetube.) Without a pull up resistor the outputs will not show a voltage change. Also you will need to check the data sheet on the nucleo f303k8 to see if it's outputs are capable of pulling the inputs of the KD1551D1 low.

Les.