In total, there are three technicians in S.T.A.L.K.E.R.: Call of Pripyat, along with two repairmen.
Cardan is the Loners technician in the area of Zaton. He is found in the rear of the Skadovsk. Due to him being an alcoholic, his offer is fairly limited unless the player brings him Vodka. The more vodka the player gives him, the more upgrades he will be able to perform, although giving him a fourth bottle will make him pass out and he will be unable to do anything for a period of time. Notice that even without vodka, he can still repair the player's equipment. After giving him the Gauss gun, he will be able to perform any upgrade he can without vodka.
Cardan provides a mission that requires the player to bring him three set of tools: Basic tools, Fine tools and a Calibration Kit. Bringing him all the tools will result in lower repair/upgrades prices, and he will be also able to perform an unique tier 3 upgrade on the Exoskeleton that allows the player to run.
Nitro, much like Cardan, requests also the three sets of tools. Bringing them all will result in lower prices, and he will also be able to perform an unique tier 3 upgrade on the Tactical helmet that allows it to detect enemy targets on the minimap.
His unique quest requires the player to find radio parts. Afterwards, he will give the player a discount.
It is worth noting that despite his affiliation with the Loners, Nitro supports the Duty faction. As such, assisting the faction against Freedom will result in lower prices from him, while assisting Freedom instead will result in higher prices.
Novikov is the Ecologists technician located in the mobile lab in Yanov. Unlike the other technicians, his offer is very limited: he cannot upgrade weapons, and he can barely upgrade armor. Completing missions for Hermann will, however, allow him to perform more upgrades. If the player does all missions for the scientists, then he will be able to perform any anomaly protection upgrade without tools, which is a large advantage if the player hasn't given all tools to Nitro or Cardan. He is also the only technician able to perform tier 3 anomaly protection upgrades.
Like Nitro, he is able to unlock the UAV module.
Apart from technicians, repairmen are also present in Call of Pripyat. They differ in that they do not have any upgrades available, but can repair equipment.
Lieutenant Kirillov is the military repairman in the Pripyat Laundromat. He is able to repair equipment for free, something which is very useful if the player doesn't want to spend money into repairing. He is able to provide the player two sets of ammunition and grenades periodically, usually after completing a mission. Also, only one time, he can give the player a Skat-9 military armoured suit and a Sphere M12 helmet. He will remain in the Laundromat until the Evacuation mission.
Yar is the Freedom repairman located in the Yanov Station. He is found in the Freedom wing of the building, and gives the player a mission that requires them to escort him in the Kopachi village to eliminate a team of Mercenaries.
In Yanov, he is normally not meant to repair equipment as the "Repair" button is missing, though it is still possible by using the 'X' button. He will repair for a lower price than Nitro.
After the Evacuation is completed, if the player does not leave the Zone and goes into freeplay, he will move to the Laundromat. There, he will be able to repair for free, much like Kirillov, but also acts as a medic.