Increasing the voltage output of a laptop SMPS

[mosafet]

I'm looking to modify a power supply to get a little more voltage out of it.

The 19.5V version of my power supply's schematic is here (not sure if I should attach it, it's watermarked).

I have the 20V version. The primary differences I see are on the feedback circuit (lower right). R301 R315 and R306 are different values on mine, presumably to increase the voltage to 20V. I want to go to 23V or so. The output capacitors are rated at 25V so kinda questionable even with the stock configuration. 35V would make more sense but I don't think I can physically fit them inside the case.

At first I thought it would be simple, just modify R301 but then I realized that would also change the 5V rail(?) and that can't be increased without possibly damaging something. Now normally I could experiment and test things to see how it's going to work but this is complicated by the fact that there are multiple parts all interacting and it's not possible to test individual modules(?). I think I might try tweaking R301 a very tiny amount and see what happens. Probably decrease the resistance and see how much that lowers the 5V. Though testing the 5V side is not my idea of fun because it's on the high-voltage side with tiny parts.

Is there any way to calculate the approximate resistor values I would need so I don't have to test a live system?

[PartialDischarge]

You would be also modifying the bias of the optocouplers. Don’t change the output voltage more than 10 or 15% max, overall there is not going to be much room, these designs are more tricky than they seem

[magic]

https://www.eevblog.com/forum/projects/modding-switchmode-psus-for-different-output-voltage-and-why-it-sucks/

The auxiliary rail is tied with the secondary by turns ratio. Increasing the secondary by 15% increases AUX by about the same. The limiting component is Q065, whose power dissipation will increase. Hard to tell more without knowing the exact voltages and Q065 package type and power rating.

R301 (and R302) set the regulated secondary voltage.
R306 sets the secondary current limit, yours must be different than 19V.
R315 sets bias of the internal reference in TSM103; range tolerated by the IC is likely pretty wide.

For peace of mind I would scope the circuit above the output rail, which appears to be synchronous rectification control. Make sure that the zeners aren't being permanently overloaded.

[mosafet]

Thanks! I had searched but somehow missed that post.

I was worried it was way more complicated than I thought which is why I posted. I may have to reconsider especially considering if changing the design requires so many component changes it's not going to be worth it.