Thread: VGA to stock NAV RGBs/RGsB: research results and questions

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I sent some materials from the service manual to Ultimarc support, and they said I need to put some resistors in series with the RGB lines. The video signals from the card are 0 to 1 volt. The screen needs -.4 to +.4.

"This will not make the video signal go down below zero (ie to -.4) but it might work. The screen might be a bit bright but you might be able to adjust it down".

So that's what I'm trying to do next.

Turbo, I don't know if I can fit a touchscreen over it, actually I've never seen one to date! Where can I buy one? How thick this is? What about the touchscreen controler with the USB cable, can it be routed anywhere I want behind the dash? And how can we program the interface properly? Or does it need to?

As for the switch between the stock screen and the PC I'm using a 4PDT relay, with a button close to the cupholders. In the picture below, the 4 arrows stand for the RGB + sync signals. (of course, one have to test the correct connections in the relay with a multimeter to make sure, but that's easy).

I was concerned about noise with such a simple relay at first, but with the relay in the open position the OE image shows no signs of noise, distortion or grounding issues of any kind. As for the computer image, so far it's not good enough to judge. The only annoying thing is the noise the relay makes when you activate it. I'll probably put it inside some thick soft foam well behind the dash if that works at all.

I purchased a touch screen overlay last summer that I plan to install on top of my factory screen. It's pretty thin, maybe 1/16". It then has a ribbon cable off of the glass that hooks up to a USB controller. I haven't actually tested it out on my Mac Mini but it should be pretty sweet. I haven't thought about how to actually mount it on top of my nav screen though. I got it for about $50, if your interested I can dig up the user that is selling them. I bought it off this forum.

To update my situation:
I picked up an S-Video cable and hooked up my Mac Mini to a television and was pretty impressed with the picture. It's not VGA quality, but for Front Row and DVD playback its perfect. I still have some tweaking to do with the resolutions, but this approach tied into the AVElectronic box is definitely going to be the route I go.

I talked to AVElectronic this week and the price of the unit is $550. For my vehicle it requires cutting into the RGB wires that tie into the screen, but I can do this in the trunk where the DVD drive for the nav is located. So that should make it easier to cut into the wires and mount the unit in the trunk, verses doing any rewiring behind the dash.

So slowly but surely my systems coming together...

That is so cool, Ladams!

Hold on with the touch screen thing, I'd like first to see if my hack on the stock screen will work or not, they I'll see from there.

Please post pictures here, if you can when you finally hook the mini up to your car.. I'm really curious about this, it really looks like the next best thing. The price sucks, though, I'm really tempted by this $167.00 8.4" screen (with the Samsung panel).

I'm keeping my options open though. Thanks for your input!

Originally Posted by turbocad6

have you tried the screen direct to the pc not through the relay? I'm concerned about the rf interferance from the relay coil being energized...

Yes, that is how it's connected at my office right now, no relays. Same patterns at office and in the garage. Lunchtime I bought some resistors, a pc board and the pots. I'll try to figure out how to schematize everything at home.

Humm, bad news. It seems that indeed my car is unique in that the display does require a rage of .4 to -.4Volts for the video signal. This also goes for the 2008 G37s, and the 2007 G35: it also requires this unique negative signal level. Idem for the 2006 G35.

The 2005 G35, though, wants RGB signal level between 0 and .8. I also checked the 2007 FX35 service manual and, although externally the screen looks about the same, the signal levels are much more standard, 0 to 1 Volt. So the 2005 Gs and the FXs all share the same screen, but for some reason Infiniti "upgraded" the others.

Why such a difference? What would be the advantage of a lower range of video signals, even one that included negative signals? Noise issues? Reliability? I googled a lot, and either one find TTL level signals (some CGA monitors, industrial panels) @ 5V or standard ISO-XXXX ranging from 0 to 1 or 0 to .7V. Not once I've something ranging between -.4 and +.4V. Only Infiniti (Xanavi (owned by Clarion) are the makers on the back of the LCD).

Enough rant. I'm trying to make this thing work using potentiometers, here is a shot:



On the top of the PCB you see the 3x 220K resistors of my first try - as suggested by the ArcadeVGA tech support (now disconnected on the picture) and on the front you see the 3x 1k potentiometers, wired as voltage dividers (basically linking the wiper and one lead). I got some success @ around .2/.3 volts, meaning its ranging between 0 and .3 volts. Any more or less and it only gets worse. That's because I'm using just a limited range of signal level with the resistor/pot solution. I needed a circuit to move the range from -.4 to 0V / +.4 to .7V. But this need simply does not exist anywhere but with Nissan/Infiniti.

Here is some pictures, all 640x480 @ 15KHz horizontal sync - I finally got to see the Start Menu bar, first time in all previous attempts:





Any window big enough to touch the lower border messes it all up:



It loses brightness, sync, everything. I can't open anything full screen. Unusable as it is.


This means that I'm on the verge of giving this all up. Not that the ArcadeVGA doesn't work, but because of some quirckness of my car. Somebody who owns a Ford already said that it does work. So I guess this is the time when the only way this thread is going to go any further is if somebody else steps in.

I'm just going to try using powerstrip one more time, now with the pots in place. And then, I'll RMA this thing, unless somebody wants to buy it.

I learned a lot in the process though, and I hope I posted enough info that can be of help for many in the process of using their stock screens. I predict that in the future, when stock screens grow bigger in size, they won't be using 15KHz sync anymore, and so they'll have to use more mainstream vga like monitors.

any luck, i would imagine its a sync issue.. Prob. because the sync frequency. is so low on the nav screens.. ANyone know of a decent converter?