I have a very long run to the back side of the house for a set of 140 LEDs. I used 16ga wire to compensate. I started it up and it does not work except for the first four lights and the sacrificial LED in my control box. I thought it may have been a bad pixel, so I switched that out and it works fine on the GPIO16 LED 1 output, but does nothing on the GPIO4 and that is at the test jumper in the box. How do I verify the output on GPIO4? DIG Quad, 752 LEDs in front on one segment and 140 LEDs in back on the second segment. 12V 29amp PS. Front works great! Any help would be appreciated
Data wires are not helped by heavier wires. For long distances, look into RS485 (differential) transceivers.
Sac pixel only works if done correctly, and that it still not as good as a real level shifter.
Since you have a Dig Quad, it already has a proper shifter, but it won’t work for longer runs. You can try switching the data line resistor, if yours has that option.