Any idea what this part is? Marked GE Y 8 1502 . Board says D12 but no polarity marked and doesn't look like any diode I've seen. From 1989 Chamberlain garage door opener circuit board. No schematic, but looks to be across a relay output carrying 120V. Searches have returned nothing of value. Also looking for schematic for Chamberlain board part number 41A3040. Board has "14LG300F" on the screen.