[Balloon] Accessing serial ports on Balloon3 CUED

Hello Ballooners

I am wanting to look up via RS232 to an external micro and still want to
retain the main console serial console use.

From what I have read there should be 2 serial connections @ 3V3 lurking
somewhere in a Ballon3/CUED box. I searched but did not find any schematics
etc.

Where can I find the info?

-- Charles