ZD-8915 (SS-331) conversion from 18V to 24V

[Hardlife]

Hi,

i have same circuit like User Spawn...
(newer version power supply (ZD150-PQ32/15) - still 18V)

Because i am not a pro  - can smoebody please help me to identify the right resistor for manipulation?
@cybermaus ?

I attached better pics...
(R21 and R22 = 472)

Thank you,
Hardlife

[cybermaus]

I've been staring at it for a while, and I think I agree with @shawn: R20 which needs a parallel resistor on it, the value is 2K4 and I think it needs a 6K8 resistor parallel on it for +/-24V

Or alternately, replace the entire R20 with1 1K8 resistor (or 182 in numeric)

Mind you, its been a long time ago, I barely understand what I did back then, and most importantly, I cannot measure any if the lines are connected to the rest of the board I think they are.
I am basically just trying to map the old to the new from the picture, and to be honest, there is one resistor too many.
Maybe for safety, you can first put a parallel 22K resistor to it or so, and see if the voltage rises to 20V

[HumbleDeer]

The universal input supply shouldn't have any trouble running from 110v. It's a flyback, so it's built to be fairly proactive in compensating for loading or duty cycle requirements. Furthermore, the universal power supply models are actually rated for 110v, so it would be a grave oversight to have it not actually work properly.

Mind you again, changing the output to 24v will increase the power draw quite a bit. A resistive element doesn't scale its current draw back in response to a higher voltage. You may need to implement an inhibit signal for the heater that pulls it down/off when the pump runs.