Maintenance notice: These forum archives are read-only, and will be removed shortly. Please visit our forums at their new location,

After a certain column, LEDs unresponsive

edited September 2012 in LED Matrix Kits
Hi! I finished soldering my Peggy 2 together and tried uploading the row/column tester sketch, but when it scrolls down through the rows, one column is illuminated all the time and all of the LEDs to the right of that column don't follow the sequence. They do faintly illuminate, so I'm pretty sure they're soldered properly. What could be wrong?

I should note that when I was putting the chip in the U5 DIP socket, one of the pins got kinda mangled and I had to straighten it out with some needlenose pliers. I wouldn't be surprised if that was damaged.

Thanks for any help you can provide. It's been a fun project!


  • Is this at about column 15 or 16?  It is most likely due to a problem at U5.  Check the pins carefully, and see if you can figure out where it isn't making good contact.  

    Another thing that you might try (if you can) is to swap the chips at locations U4 and U5, to see if the chip itself is OK.  If the problem moves when you do that, the chip probably needs to be replaced.
  • Thanks for your reply. When I switched the two chips at U4 and U5, the problem was fixed! I think maybe the pins just needed to be straightened a little better.

    Thanks again!
  • I am having the exact same issue where columns 0 - 16 are dim and 17 - 25 are bright. When I swapped the U4/U5 chips then now the right side is brigh and the left side is dim. Any suggestions?

    Just prior to all this I had tested all the LED's lit up correctly before I started soddering. I then soldered a four in the uppoer corner and everything was ok. I then started to sodder the first column down and as I was testing I noticed that none of the LEDs would light up at more and have no idea what happened.

    I may end up starting over and using the socket example I saw which seems easier to assembly than dealing with all these LED leads.

  • I'm not sure that I understand the situation fully; perhaps you can clarify a few things:

    1.  Columns 0-16 are dim, and 17-25 are bright, even after swapping U4/U5.  Correct?

    2.  Do you have some other LEDs that are not lighting correctly?  

    3.  Have you finished installing the LEDs yet?
Sign In or Register to comment.