The easiest way to get this is to install The Sith Lords Restored Content mod available through the Steam workshop. Not only does it vastly improve the state of the game (especially late-game), it spawns HK-50 droids which will attack you on every planet in the game after you leave Telos. Destroy them to get all the parts you need to restore
. There are four parts in total:
Vocabulator
Control Cluster
Droid Processor
Chassis
I think you might need one rank in the Repair skill as well or boosting gear to install it. Just interact with the droid after you find each part or once you have collected them all and you will unlock the achievement.
If you don't want to or can't install TSL:RCM for whatever reason it will take quite a bit longer to get this. There is only one or two of each part in the following locations:
Vocabulator: Loot the HK-50 droid on Peragus
Control Cluster: Loot one of the droids on the Telos plateau after they
. Also available for sale by the Sullustan mechanic on Dantooine.
Droid Processor: Available for sale by Kodin the junk merchant in the Nar Shadaa landing area and 1B-8D the droid junk merchant you have to interact with as part of the main quest on Onderon.
Chassis: Loot it off one of the HK droids during the part of Nar Shadaa where you play as T3-M4 for a bit.