All, need some help if you can.
I am trying to re-purpose a laptop power brick and need to change its output voltage from 19V to 12V. I reckon I can do so by changing the resistors in the feedback loop, am I right?
It's a LiteOn model PA-1650-32HN. I tried to find its schematic but not sure if what I found is right (see page 7 of this PDF, and also attached:
https://ac-dc.power.com/sites/default/files/PDFFiles/der197.pdf). There are definitely some differences between the schematic and the board.
I also tried tweaking the potentiometer on the board but doesn't seem to work, seems to only change the voltage slightly (it was set with some sort of glue that I tried to remove, I guess factory calibration?).
There is a chip on the board close to what I believe are the feedback resistors, marked "1002 PGUY". I can't find what chip that is to try and understand how the feedback loop works. Or maybe that has nothing to do with the feedback...
The only other chip on the board is what I believe to be the main switching controller. I'm having a hard time reading it without proper magnification but I think it's something like SC1L704, or maybe SC1170. The "S" could be a "5" maybe.
Here is a picture of the board but I didn't manage to make it visible...
https://1drv.ms/u/s!AgoNznOUIIVFi9sfcqddvS3mk_MwtgAny further advice on how to approach this? I am going to use it for powering a relatively high current 12 V device (~2-3 A).