Oh, no. I'm running them on separate power supplies. I want to wire the PSOne screen's audio (speakers + headphone jack) and video display to their respective NES board counterparts. But while keeping the original NES's audio/video out intact

I hope when you say "wired to the NES" you aren't planning on connecting the power directly to the NES' power rails. The PSOne LCD requires something between 7.5 - 9v at like 3amps in order to power up.

Thanks! Ideally, I'd like to have the PSOne screen wired to the NES board (and mounted), so it can use the PSOne screen's audio (the speakers and headphone jack) and video. And then just fold the screen and unplug it when not in use. And use the NES's composite video and mono audio (RCA) on like, a television.
I just wasn't sure if the RCAs are still usable if I mount and wire the PSOne screen?
Does that make sense?

Ah, if you have one that makes it a much more understandable decision.

So, you are looking to wire everything up and still have the jacks for external audio and video?(same time or when the PSone monitor is not in use?)
You can do speakers and a headphone jack.
I would post my own pinouts but I am quite busy with life,
The ModRetro Forums and ShockSlayer Forums have some good info.
http://kyorune.com/modding/ is another good resource.

I'm actually thinking about wiring it to the board. Would I still be able to use the RCA jacks on the NES on a different screen if needed? And if I wire the sound from the PSOne screen to the board can it use both the speakers and the headphone jack?

Edit: sorry, didn't see the other replies. The reason I want to use the PSOne screen is because I have one in a box with a lot of my old stuff

TFT monitors are cheaper and more convenient. at least for me. I got a 7" one that I use with my c64 and my NES. Has 2 composite inputs that I can switch between so I don't even have to unplug the consoles each time. The 3.5" ones also should have 2 AV inputs.

You are better off buying a 5"-10" backup monitor off eBay.
A lot cheaper, and most look better.
Adding speaker is quite easy as well.

Thanks again!

Well, the mounting would be a bit of a hack. On mine, there is a hinge part that has thumb screws and a PSone AV plug. It screws to mounting holes on the PS1; for the NES you won't be able to do the same. SO how creative you want to be? I mean, with enough duct tape all things are possible
Yogi

Thanks!
I guess mounting it to the NES would be similar to putting it on a PSOne?

Funny you should ask, just talking 'bout LCDs with someone else. Yes should be fine. I've used one, as well as little portable 5" DVD player as a screen. Even found a 'in car' LCD screen. Very handy.
The PSOne screen I have has AV and Pwr inputs. Just need a RCA cable and a power pack.
Yogi

Hey guys! New account (not new user), but can anyone tell me about the process of getting one of those PSOne monitors/LCDs on my NES? And does the original composite video out stay intact? I've seen a couple examples, but I didn't really follow how they got it working. (Sorry if this is basic stuff.) Thanks in advance!