4 devices and one of them defective, what is the fastest way to find which one is defective

Question

I have problem to solve this puzzle

4 devices and one of them defective, what is the fastest way to find which one is defective

and this is a picture for demionstation

you can generate as many as you want, all of them go to the orange area and then adding them and once you click calculate it needs one hour for the process

Now one of them is defective, it generates 1 instead of 2

What is the fastest way to know which on of them defective

you can do it in one calculate but how ?!

Answer 1

Activating generator $1$ once, generator $2$ twice, generator $3$ three times and generator $4$ $4$ times gives the results $19,18,17,16$ , if generator $1,2,3,4$ is defect respectively.