Question on wireing a transformer

[whomeno]

I need to wire a transformer up for the board. I know how to do the hot and common, but where do i pull the ground from?

[antonis]

Ground (for CT transformer) should be connected right on reservoir caps joint..
Can't trace well your layout but it looks like it utilizes single supply configuration..
(or else, it's NOT designed correctly and DO NOT attempt to power it..)

In case of single supply, GND is taken from last bottom row (D5/D6 anodes, C16 negative leg..)