The red cable on the right hand side with a black and white wire in it comes from the transformer. The smaller cable with two wires on the left hand side comes from the doorbell… I absolutely can’t remember how this was wired when I took it out to paint the wall… Any clues, guys? Dudes?
A typical doorbell is wired as such:
Wirenut one wire from the transformer to one wire to the doorbell. It doesn’t matter which. Wire the remaining transformer wire to the center screw on the chime (labeled transformer). Wire the remaining doorbell wire to the right screw on the chime (front door).
If you have a ring doorbell, you may need to replace the transformer with a 24v one. The directions should tell you.