If I power the Uno via USB the 5v pin reads 5v, as expected. If I power the board through Vin or the barrel adapter with 12v, the 5v pin reads 3.09v. If I power the board through Vin with 12v and USB, the 5v pin reads 4.5v. No other pins connected. Is there a way of fixing this board?

12v in 3.09v out Arduino Uno, fixable?

Topic		Replies	Views
Powering the Uno General Electronics	10	3724	May 6, 2021
Arduino UNO 5v pin wrong voltage! IDE 1.x	3	1136	May 5, 2021
Arduino voltage regulator feeding more voltage than input?! General Electronics	11	5993	May 6, 2021
The +5volt rail varies with different power supplies General Electronics	6	936	May 6, 2021
Getting more than 5v from the UNO 5v pin Motors, Mechanics, Power and CNC	8	769	October 16, 2023