This is somewhat a followup to this post:
https://www.eevblog.com/forum/beginners/why-is-my-power-supply-broken-(with-schematic!)/
Schematic attached.
Background of previous post: Essentially with the previous post, I had found the fault on the monitor but damaged other components in the process.
What I want to do: I've decided that instead of trying to further repair the monitor PSU, I instead want to cut it in half between the primary and secondary (
image B1), but retain the PFC circuitry on the primary side (for use with other projects) and retain functionality of the 5V buck converter (on the secondary side).
My understanding of the circuit: By cutting the board, I will be disabling the 5vSB power rail, but I need to leave transformer T
B801s untouched to retain functionality of the PFC circuitry. Based on
image S20, it looks like I can simply disregard the PC803s associated circuitry, but that I do need to retain the functionality of PC801s and PC802s (both are optocouplers, circled in
image S20).
Solution?: I'm thinking that I can simply replace the PC801s and PC802s transistors with resistors, to enable the PFC circuitry. Is this correct, and if so, what value of resistors should I use? I understand that by replacing PC801s and PC802s transistors with resistors that the PFC will always be active, wasting energy, which I understand.
Further, to use of the secondary side, I simply plan to use an external 19v laptop power supply connected directly to the secondary side of the T
M801s transformer (the one creating the 24v and 5.3v bucked supply rails). I'm thinking that the monitors other components (mainboard, CCFL backlight) will be perfectly content with getting 19v instead of the original 24v.