The 502 V1 and V2 are are operationally exactly the same until you press the TX button. 
They have exactly the same components, specification and sound.  It is only when the TX button is pressed that the operation of the V2 changes.

Without the TX button being pressed, the V1 & V2 both have electronically balanced outputs. 
When you press the TX button on a 502 V1 the primary output changes from electronically to transformer balanced, there is no secondary aux output on the V1.

When you press the TX button on a 502 V2, nothing changes on the primary output. It remains electronically balanced.
The TX button now enables a second electronically balanced Aux output which takes its signal post everything so the mic split is at the final output.

This option is only available on Midas L6 or L10 racks and a small number of compatible 500 Series racks. 
The TX switch should not be selected on non compatible racks as some use these pins for other audio paths.