Limits of a meanwell supply trim?

[coppercone2]

I got one that goes from 27 to 19V.

Can you change the resistor bias network to go even lower, i would like it to be 12V, its working at reduced amperage.

[Siwastaja]

Stability cannot be guaranteed with such heavy modification, even with reduced load, unless you analyze the complete design. These supplies are basically designed as fixed-voltage supplies and the trim range is quite large already. One way to find out is to try, but it's wise to ramp through zero to full output current and try capacitive loads as well just to be sure.

[coppercone2]

no guts no glory

maybe it will oscillate in a way that it will power LEDs at the right voltage still? :p

[wraper]

Most likely it will just shut down due to undervoltage protection on PWM controller power pin. Hint: usually it's powered from auxiliary transformer winding. Basically it would work only if PWM controller has independent power supply for it.

[coppercone2]

I tried adding series resistance to the pot (it goes down when the pot resistance goes up) but I think its limited to like 19V some how in the chip itself, maybe a ratio detector or something? It's just a trimpot to ground with a series resistor and a PCB jumper where the trimpot is used as a rheostat to ground. Other end goes to a AP4310

not sure if its worth investigating further unless someone has a success story because it looks like it will get complicated to even attempt this.

edit: more complicated, missed a trace may have put resistor in wrong place in signal chain

edit2: yes I think I just changed the entire impedance of the voltage control and OVP circuits, small trace comming out of a unassuming decoupling capacitor. Need to try again......