I was working on a furnace which uses 120v and the control circuit uses 24v. I checked the two secondary leads on the transformer and got 0v. Then I checked the primary hot lead and the chassis and got 120v. Turns out the primary neutral had a bad connection. My question is when I checked either secondary lead (without the primary neutral connected) to the chassis i got 12v. How could I get anything when there is no current flow through the primary side of the transformer? Thanks