I'm using a 74HC595N shift register to light up 8 LEDs but for some reason they won't turn on even though current is flowing through all of them. I provided an image of my circuit below, there is a test LED for checking current flow:

This is my circuit

I am using a 9A103G resistor network to connect all the LEDs to a common ground. I have tried this with 8 individual 330 ohm resistors in the past but the result is the same, and every time the problem was with the ground wire, current is not flowing through it even though all the resistors I've used showed that current was flowing through them (see below):

Current going through resistor network

The following image shows the same test LED not lighting up when connected to the common ground pin of the resistor network:

No current going through ground wire

I could use some help fixing this issue because it is preventing me from using shift registers for future projects (this only happens when I use shift registers) - I would like to know what is causing this problem so I can avoid it later on. Thanks in advance!

  • 3
    You're short circuiting your LEDs with the breadboard. Rotate them 90°.
    – Majenko
    Jun 7, 2021 at 15:52
  • That was the problem!! Thank you so much! I forgot about the columns.
    – user77534
    Jun 7, 2021 at 15:56
  • Good pictures by the way.
    – timemage
    Jun 7, 2021 at 16:33

1 Answer 1


(Just to illustrate what Majenko is saying.)

This is the inside of a breadboard:

enter image description here

All your connections are on one side of that; you've tied everything to a single point.

  • Yes you're right, thank you
    – user77534
    Jun 7, 2021 at 16:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.