Question Mystery Screen/Driver Board (help)

[Lemoncake]

What’s up everyone? So I am currently in possession of an old car backup camera that I was planning on using as a screen for a portable project, but I can’t find ANY documentation about it online whatsoever. Here are a couple photos:


Here’s what I know:

It’s a 7-in screen

It has 2 inputs (AV 1 and AV 2)

It’s only cable input is a single 6 pin barrel plug (see photo)

It has ZERO branding information on it whatsoever (except for some chip company called Star that made something on the driver board)

It used some overkill screw mounted stand that attached to the back of the plastic case

In terms of it’s more technical info, here’s what I know: it’s advertised (on the back of the driver board) to run off of 24v, but I was able to coax it into running as low as 7.5v (with inconsistent boots) and it works comfortably at 12v as well (unless using a lower voltage is causing some issue that I’m unaware of. lmk if that’s the case).

I don’t know what kind of video signals it supports (none of the guides I read were clear but I did figure out it is specifically called a DIN 6 Cable or a PS/2 Connector).

If anyone has ever worked with something like this before and they might be able to offer some tips as to what video it supports or any reference materials like a user manual for the monitor as a whole, I would be extremely grateful. So far I’ve just been straight up wiring a component wire to the AV 1 from a trimmed Wii that I’m not even sure still works and unsurprisingly I’ve no luck getting any signal out of this thing. Hopefully the more observant and intellectual method of diagnosing this whole thing will yield better results than a quick solder job and some wishful thinking lol. Thanks I’m advance for any contributions made!

 

[Stitches]

I remember those. What you have there is a basic composite only screen. The two AV pins are your two composite inputs which the screen can switch between via the source button. They can be easily modded to run on a lower voltage by probing the inductor pads here with a multimeter.

One of them will be carrying either 5v or 3.3v. You can remove that inductor and supply the matching voltage from your regulators to power the screen

 

[Lemoncake]

Thanks so much. That fact that it natively supports composite is a relief (may not be ideal for you veteran portablizers, but as someone who only has a 33.333333333333…% success rate at trimming Wii’s, I don’t mind at all as long as I can see that glorious title screen of my Paper Mario Virtual Console WAD ). I’ll get back to tinkering with it as soon as I confirm my Wii itself still works and hopefully I can finally get to using it in a project! Where would we be without you, Stitches? Thanks again.

 

[Lemoncake]

I remember those. What you have there is a basic composite only screen. The two AV pins are your two composite inputs which the screen can switch between via the source button. They can be easily modded to run on a lower voltage by probing the inductor pads here with a multimeter.
View attachment 32343
One of them will be carrying either 5v or 3.3v. You can remove that inductor and supply the matching voltage from your regulators to power the screen

Hey! Sorry to bother you again, but I just realized I had one more question. Is there any chance you know of a way to bypass the need for a power button so that it can turn on at the same time as the Wii? It’s circuitry is weird as it requires you to just tap the power button from the dedicated button PCB to turn it on. Bridging the tact switch on the PCB does absolutely nothing. I’d love to forgo the button PCB entirely and I’ve heard of ways you can bridge connections on the driver board ti achieve that result.

 

[LCandell]

When you wire the “BACK” pin to 12V (I don’t know if works with a lower voltage) the screen turns automatically on any of the AV inputs (normally AV2), this lets you remove the entire button board.

Sometimes removing the board doesn't let the screen to turn on, but wiring the button board -without buttons- solves this issue

You can see the bridge made in blue wire
Also the board wired into the screen driver without buttons

 

[Lemoncake]

That worked like a charm! After wiring up BACK to the 12v line and hooking it up to the multimeter, I get instant boot!

However, there’s still one problem. Like you said, it always turns on with AV 2, which unfortunately happens to be the back up camera input. I can still get a component signal from the Wii onto it, but that overlay doesn’t go away. It just displays on top of it. I tried bridging the “input-switch” button to see if it would change inputs instantly on boot, but that had no result and I’m assuming I’d need some sort of current delay to get that to work. Does anyone have any experience working with this kind of issue?

 

[LCandell]

Unfortunately I think your screen has that overlay by default on AV2, because this configuration is for the cars, when you go reverse, the screen automatically receives a signal in "BACK" to activate the screen. You can't change the AV input in which the screen turns on, or remove the overlay, maybe with some reprogramming, but getting the tools doesn't worth it.

-Do you have the same overlay in AV1?

If you don't, your idea is correct, you can use a microcontroller-like device to send a delayed signal to the button pads (normally a logic 0 or GND signal), maybe an arduino is the easiest way to do it

Also you can try what happen if you remove the bridge once the screen is turned on, it will still turned on, or it will change the AV input?