12" I3V Build

[printbus]

Thanks for posting a pic of the relay. A few have mentioned the built-in relay, but I believe you're the first to provide a picture of it. This reveals the heat bed is using the same 30-amp G8QN Omron mechanical relay that is used on the standalone relay board.

To go the PID route, you'd first want to remove the two small black wires from the heat bed. You might be able to reuse the wires to control the SSR, but the SSR will require you to keep the polarity straight between the electronics board and the SSR. The mechanical relay didn't care.

After that, removing the relay depends on how comfortable you are in attempting to remove it. The two pins that solder to the wide traces would be a problem for some. I'd probably just jumper across those two pins with some heavy wire, leaving the relay there in case you roll back to using it. There'd be two options to jumpering across the pins. You could move the heavy gauge wire from the wide trace just going to the relay to the relay pin connecting to the other wide trace, but the solder pad there is smaller. The other option would be to scrape away the soldermask on the two wide traces where they are the closest and build a solder bridge to short the two traces together.