Video on Nav, another approach
#64
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Thought this thread had died a while back, so I haven't been following it. A couple of updates...
I have been working on a way to eliminate the AC inverter. I have successfully installed a 12VDC power supply in an XBox. It also has a sequencer that automatically powers the XBox up a few seconds after the ACCY power comes on, and shuts it down several seconds after the ACCY power shuts off.
One problem though. The Audio Authority converter cannot be powered from the vehicle's 12V power as I had originally thought. Apparently it requires that it's DC supply be floating with respect to the video signal ground. If you try to operate the Audio Authority converter from the vehicle's 12V power you will not get any video out.
So I need to find a different converter or come up with a work-around for this to get a working "12 volt only" setup. Another possibility is finding an xbox bios that provides RGB video out directly.
Also I have installed a small auxiliary battery and battery combiner in the trunk. The battery combiner effectively ties the aux and main batteries together while the engine is running so that both batteries stay charged. With the engine off, the batteries are separated.
I have the aux battery powering the xbox so now I can start/stop the engine without the x-box resetting.
-jim-
I have been working on a way to eliminate the AC inverter. I have successfully installed a 12VDC power supply in an XBox. It also has a sequencer that automatically powers the XBox up a few seconds after the ACCY power comes on, and shuts it down several seconds after the ACCY power shuts off.
One problem though. The Audio Authority converter cannot be powered from the vehicle's 12V power as I had originally thought. Apparently it requires that it's DC supply be floating with respect to the video signal ground. If you try to operate the Audio Authority converter from the vehicle's 12V power you will not get any video out.
So I need to find a different converter or come up with a work-around for this to get a working "12 volt only" setup. Another possibility is finding an xbox bios that provides RGB video out directly.
Also I have installed a small auxiliary battery and battery combiner in the trunk. The battery combiner effectively ties the aux and main batteries together while the engine is running so that both batteries stay charged. With the engine off, the batteries are separated.
I have the aux battery powering the xbox so now I can start/stop the engine without the x-box resetting.
-jim-
#65
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jstjohnz,
Thanks for the update. I hope you can share with us (or me
) the schematic you used for the Xbox power supply as mine will be going into my car soon.
I wonder if your Audio Authority unit would consider the ground to be floating if you used a LM7912 Fixed voltage 1A negative power supply regulator? It would be a whole lot easier than going with another converter.
Thanks for the update. I hope you can share with us (or me
![Big Grin](https://www.clublexus.com/forums/images/smilies/biggrin.gif)
I wonder if your Audio Authority unit would consider the ground to be floating if you used a LM7912 Fixed voltage 1A negative power supply regulator? It would be a whole lot easier than going with another converter.
#66
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Originally posted by LS007
[
Thanks for the update. I hope you can share with us (or me
) the schematic you used for the Xbox power supply as mine will be going into my car soon.
I wonder if your Audio Authority unit would consider the ground to be floating if you used a LM7912 Fixed voltage 1A negative power supply regulator? It would be a whole lot easier than going with another converter. [/B]
[
Thanks for the update. I hope you can share with us (or me
![Big Grin](https://www.clublexus.com/forums/images/smilies/biggrin.gif)
I wonder if your Audio Authority unit would consider the ground to be floating if you used a LM7912 Fixed voltage 1A negative power supply regulator? It would be a whole lot easier than going with another converter. [/B]
I am using a 12V ATX power supply that I bought on EBay. The same unit is available I believe at mini-box.com. There are 2 versions of the power supply, identical except for dimensions. They also sell a power sequencer. I bought the pair on ebay for about $80.
Both of these modules fit nicely iwhere the standard Xbox supply would normallly sit. I mounted a 6-pin connector on the back of the xbox wired for: GND, +BATT, +ACCY, +12V OUT, and PWR SW. The +12V out is to power the converter, the PWR SW signal is for remote power control. The box gets it's power from +12V BATT, and uses +12V ACCY to switch on and off using the sequencer.
You feed +12V Batt and +12V ACCY to the sequencer. About 5 seconds after ACCY power comes on, the sequencer turns on the +12 to the power supply, then pulses the power switch lead to turn on the xbox.
When ACCY goes off, after several seconds the power lead is pulsed to turn the xbox off, then +12V is turned off several seconds after that.
It's designed for use with a PC, but the XBox is similar enough that it works just fine. My plan is to have a SPDT center off toggle switch at the dash that will tie the sequencers ACCY input to either BATT, ACCY, or open. That will turn the XBox always ON, always OFF, or AUTO where it will go on/off with the ACCY power, after a delay.
Basically the Xbox power supply is ATX compatible with the exception of the level of the standby voltage (+5 on ATX, +3.3 on Xbox), and the levels and polarities of the PWR GOOD signal from the supply and the PWR ON signal to the supply.
I am just dropping the +5V STBY output of the supply through 2 series diodes to get about +3.3 for the Xbox. I run the PWR ON signal from the XBox to an NPN transistor to invert it, and I am just leaving PWR OK disconnected.
As I mentioned earlier I have installed an aux 12V battery in the trunk to power the xbox and a 2-way radio. This allows the Xbox to keep running if the ignition is momentarily turned off, or ieven when the engine is cranking. I am using an 18AH AGM battery that fits nicely in the empty space behind the luggage compartment junction box. It connects to the main battery through a battery combiner (West Marine), so that both batteries will charge while the engine is running, but they are separated when the engine is off.
By flipping a toggle switch in the trunk I can force the battery combiner on. If the main battery is dead (not uncommon for an LS430 that sits unused for a few days, at least for me), forcing the combiner on should charge the main battery from the aux battery, at least enough juice for a start.
As far as the Audio Authority converter goes, I am a bit puzzled. One thing that is a bit weird is that the normal coaxial power connector is wired tip negative (which I of course learned the hard way). However, internally, the negative side of the supply is what is wired to ground.
I assume that it is some sort of clamping/DC restoration issue. One fix for this is to just power the converter through a small 12V DC-DC converter. They are fairly cheap and there is room either in the converter or in the XBox.
Also I am looking at another converter, this one is NTSC -> RGB and that would open up the possibility of being able to switch in other video sources such as a backup camera. It's also cheaper than the Audio Authority, $125 from an outfit in Australia (www.converters.tv).
What is ironic about all of this is that the Xbox is SUPPOSED to be able to output RGB directly,, but the implementation is broken. I have heard of a couple of hacked Xvox bioses that enable the RGB output mode to work correctly, but they lack some of the features of the bios that I am using, such as large HDD support. Also there would still need to be a bit of external circuitry to combine the H and V sync signals.
I am going to try the DC-DC converter approach jsut to be sure, but there is no reason why it shouldn't work. Also I will try to call Audio Authority to see if there is any way to make their box work with an external DC supply referenced to signal ground.
Basically the whole 12V power idea is turning out to be more work than I thought but it should make for a cleaner installation. I am thinking about mounting the XBox where the tool kit normally sits, that way all of the hardware will be concealed.
-jim-
#67
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These two units have VGA(RGBS) input and output. and a composite or svideo input. Couldn't you splice this between your nav unit and HU on the rgb lines. You wouldn't need a relay because these things have the switch built in. I just don't know what they do with the output frequency and if the nav display will handle it
http://www.startech.com/ststore/item...r=topbarav.htm
http://www.cablestogo.com/product.as...2011&sku=40227
http://www.startech.com/ststore/item...r=topbarav.htm
http://www.cablestogo.com/product.as...2011&sku=40227
#68
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The converters need to be analog R,G,B with a composite snyc. to work on our navigation systems. Correct me if I'm wrong, but I always thought computer displays (typical VGA) are digital TTL RGB and the sync. is verical + horizontal TTL.
#69
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Not according to this:
http://www.epanorama.net/documents/pc/pc_graphics.html
I don't know about the sync though.
http://www.epanorama.net/documents/pc/pc_graphics.html
I don't know about the sync though.
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