The following are the locations that the Quasar Machine's signal traces to in order:

Wards Access Corridor
Starting at the Medical Clinic, go up the elevator toward the Presidium. Take the corridor to an area where people are talking. Look at the terminal on the wall.

Financial District
At Volus' Office, behind Volus.

Emporium
After exiting Volus' office, turn right and go past the Emporium Shopkeeper to a back hallway. Then, turn right again. You will encounter an A.I. that threatens to blow you and itself up. After the conversation, select the A.I., and input the following code to override: TRIANGLE, SQUARE, TRIANGLE, CIRCLE, SQUARE, CIRCLE, CIRCLE. Finish before it is done Siphoning off credit to get the credits.