G-Vision LCD backlight + Macs

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Jon
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G-Vision LCD backlight + Macs

I recently acquired a G-Vision S5FX-TA-C 15" LCD XGA touch-screen. It was in VERY sorry shape when I dug it out of the pile of misc stuff, suprisingly not from Surplus Exchange. It had a shattered 3M touch-screen, which is why it was in the pile, I'll bet. I hooked it up to a 12v feed from a PC p/s (it is claimed to need 12v@5A!) and tried it out w/ said PC. Worked great, except for the nicks and scuffs from the broken touch screen that I have removed, and a single pixel blue line down the very left side. The real problem is that when I plug it into a Mac, the backlight shuts off. It didn't have any trouble on a PC at all. If I jack into my iBook, the LCD shows the image but the backlight cuts out after about 1 sec. Same on a Beige G3's stock video. I have yet to try the out put of the stock ATI card in the Power Computing Power Wave 120 I just got, but I'm assuming it might have the same results.

Any ideas, tips, pointers? It's perfect for hacking, if I could get it to work with a Mac. If not that sweet 15" of LCD goodness will be stuck on a PC hack. Secret

Jon
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Editable Linkage

http://www.touchboards.com/gvision/s5fx-ta-0121.asp OEM seller with specs?

http://www.gvision-usa.com/s5fx.htm Manufactuer spec page, has link to .pdf spec sheet.

http://www.focusmonitors.com/focus/products/s5fxof.html OEM reseller with a reprint of most of the specs from the .pdf

http://www.3m.com/3mtouchsystems/ 3M Touch Systems, the S5FX model I have takes a capacitive type ClearTek screen.

Somewhere I saw that is is a Panasonic LCD in this, but I don't rememebr where I saw that, and the LCD itself doesn't have a label handy.

The monitor has the VGA->LCD controller, the button panel, the touch-interface (only connects to the rest of the monitor to get 12v power, otherwsie it is really fully independent), and the power converter, takes 12v-> 12v, 5v, GND, and I'm sure does a little filtering too.

Jon
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Results of more testing: U

Results of more testing:

Use molex HDD power connector of the G3 to power the LCD and it works w/ both the G3 and the iBook! Great! Go back and use the PC power supply and the backlight continues it's shut-off wierdness w/ Macs. Is there anything odd between the power supplies that I don't know about? It's just tapping the 12v and Gnd off a standard HDD power connector. The G3 outputs less power than the PC (150w vs 250w) and the LCD works fine for the PC. If it was a difference btw power and VGA grounding issue, then it shouldn't work on the iBook at all, right? It works, so I'm glad, but the way it fails stumps me.

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A PC Power Supply needs a loa

A PC Power Supply needs a load (typically at least 20% of capacity) on the +5V in order to function... most will just shut off without it... a cheapo may just fry. Some may need it on the the 12V too. I've seen a 1 Ohm resister or a 5V car light bulb recommended.

Jon
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Would a PC supply lower power

Would a PC supply lower power output? When doing testing w/ the PC supply I left the CD and HDD plugged in and pulled the mobo power connectors. I dunno how much of the 5v line they use, but it should be some. When the problem occurs the suppy doesn't shut off, the HDD and CD keep powered up and the LCD functions. Only the backlight goes out, and the only way it is attached to the PC supply is over the 12v line. Odd.

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voltage threshold?

There may be some voltage/current threshold that needs to be met before the backlight will stay powered. The backlight, being powered by the inverter, might be a bit more tempermental than the rest of the system.
The reason I thought of this was based on -somewhat- similar problems I was having when I first made my Takky CC...I had a cooling fan running without problems, but there wasn't enough juice to get the mobo to stay powered up. Adding more load to that PSU did the trick.

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Usually PC supplies have high

Usually PC supplies have higher ratings... 20A worth of +5V on a 220 watt I have here... I'm guessing a HDD draws less than one amp (of +5V) max, and a CD maybe nearly nothing when not in use.

Jon
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I just di more testing. Yes,

I just di more testing. Yes, the PC power supply load was to blame. This time around I left the mobo plugged in and booted the PC with the LCD plugged into it. Then I swapped the VGA cable over to the iBook and it worked like it should. More load on p/s == better backlight performance. Now if the LCD didn't look so washed out w/ the iBook. On the PC it looked ok. Tried calibration, but no good. I'll have to try it w/ a different Mac and see if things change on that front.

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