Excellent! Great work fixing that. Now we can work on the original problem.
Yes, the place to start is with the optocoupler circuit. Right now, the only thing that i’m sure of is that the LED in the optocoupler’s aren’t lighting up. That could be caused by several issues. Let’s start with the voltage to that circuit. As you see on the schematic, R7 and R8 should have 5V on one pin. Are you getting 5V both or either of them? If not, this diagram shows the 5V rail to both those resistors:
https://zeppelindesignlabs.com/wp-content/uploads/2023/06/5v-rail-jpg.webp
If 5V isn’t getting to both of them then the problem is probably a broken trace or something between VR5 (the multiplier pot) and R7…assuming VR5 and VR1 (spacing pot) are getting 5V. If R7 and R8 aren’t getting 5V then run a jumper as needed from any 5V source, but preferably from C9 seeing that it’s close to the source.
Let me know if that works or not.
-Brach
