How do I wire up this transformer for 110V mains?

[454Casull]

http://www.apexjr.com/images/66938_sc7.pdf

What are the third wires for on the primaries?

[infinia]

I think they are just extra connectors (leave them open by insulating them) they are the same color code.
parallel 120V PRI windings ( dots to dots) or BLK to BRN and WHT to BLU etc

If your 110 is really 120 > No load voltages s/b close to 43 VDC
Boderline HV >>> PS let use know if your chip amp does OK with your mains measured.

[AndrewT]

Hi,
use a mains light bulb tester to power up each time you change or add something to a mains powered project.

A wrong wiring of the two primaries can quickly burn out a perfectly good transformer if the fuse does not blow quickly enough.

[454Casull]

nm]