To retrofit the switching power supply to an adjustable 90V, you can choose a linear regulator model LM317. The voltage regulator has the function of adjustable output voltage, which can be controlled by adjusting the resistance. At the same time, the LM317 also has overload protection and short circuit protection, which can protect the circuit from damage. In addition, the LM317 also has a stable output voltage and low ripple noise to provide stable and reliable power output. Therefore, it is a good choice to choose LM317 as the adjustable voltage part of the modified switching power supply.
For converting a switching power supply to an adjustable 90V output, you may consider using an adjustable voltage regulator model number LM317. LM317 is a commonly used linear voltage regulator with a wide range of applications and adjustable output voltage. You can design a suitable circuit according to the LM317 data manual and application circuit to achieve the function of adjusting the switching power output to 90V. Ensure that the relevant safety specifications and circuit design principles are followed during the design and retrofit process.