here are the photoes that you asked for. I think that the problem may could be in one of the resistors’ value on the ac board (but i followed what was indicated on the schematics, so I don’t know). There are 4 10kohm through hole resistors on the main board because I ran out of the smd version.
The main board seems to work great. Also the pcf8574 on the AC board works, because it changes its outputs according to the running program.
Thanks for your help and time,