Thread: Dynamix LCD "no input signal"

I missed the bit where you said what the mobo is. I looked up the mobo in your carpc specs under your name on the left (j7f2we1g2e), but that doesn't have an i915 chipset. I looked up the two links in your sig but all I got was some pictures.

If your mobo kicked out low voltage sync (3.3v instead of 5v) then the monitor may have trouble detecting that. I think I remember that some motherboards do this, and some monitors have trouble with low level sync. Not knowing which mobo you have and having a hazy memory about the specifics of the problematic system in the past definately doesn't help things here.

Originally Posted by Rob Withey

I missed the bit where you said what the mobo is. I looked up the mobo in your carpc specs under your name on the left (j7f2we1g2e), but that doesn't have an i915 chipset. I looked up the two links in your sig but all I got was some pictures.

If your mobo kicked out low voltage sync (3.3v instead of 5v) then the monitor may have trouble detecting that. I think I remember that some motherboards do this, and some monitors have trouble with low level sync. Not knowing which mobo you have and having a hazy memory about the specifics of the problematic system in the past definately doesn't help things here.

Sorry, still not updated my car specs. The mobo is the one you can see here:

http://www.idotpc.com/TheStore/pc/vi...&idproduct=425

How can I check the voltage sync?

Possibly useful threads:

http://www.mp3car.com/vbulletin/lcd-...3-3v-sync.html
http://www.mp3car.com/vbulletin/gene...3-3v-sync.html

For other info, search for "3.3 sync".

Mod basically uses TTL to buffer (and amplify) sync signal from 3.3v to 5v.

Originally Posted by l1nk

How can I check the voltage sync?

Connect it to an oscilloscope.

Originally Posted by Rob Withey

Connect it to an oscilloscope.

Unfortunately I haven't one!! Just some cheap analogic and digital multimeter
Anyway I'll try to read the threads you linked. Any other idea/advice is greatly appreciated! Thanks

Originally Posted by Rob Withey

Possibly useful threads:

http://www.mp3car.com/vbulletin/lcd-...3-3v-sync.html
http://www.mp3car.com/vbulletin/gene...3-3v-sync.html

For other info, search for "3.3 sync".

Mod basically uses TTL to buffer (and amplify) sync signal from 3.3v to 5v.

Just tried to read signal values from VGA output with digital multimeter; On pin 13 (Hsync) of integrated VGA I've read about 2.36V while on the same pin of the old S3 I've read about 4.50V.

So, no 3.3V and not 5V but anyway a great difference between the 2 VGA outputs. Do you think this is a good reason to try the mod you suggested to me yesterday?

You won't get a good peak reading from a cheap digital multimeter. You might be able to build a peak sampling circuit from a diode and capacitor to improve this method of measuring (use sync to charge cap, use diode to prevent cap discharging back into sync, so cap charges to peak).
Personally I'd just quickly knock up the mod on a bread board to try it out. If it works then build a proper adapter cable (VGA15->VGA15) to include the booster.

But then I'd mess about with electronics for fun without a second thought.

BTW: you can of course knock this "mod" up as a modified VGA cable - you don't have to dive right in modifying either your mobo or your screen.

Originally Posted by Rob Withey

You won't get a good peak reading from a cheap digital multimeter. You might be able to build a peak sampling circuit from a diode and capacitor to improve this method of measuring (use sync to charge cap, use diode to prevent cap discharging back into sync, so cap charges to peak).
Personally I'd just quickly knock up the mod on a bread board to try it out. If it works then build a proper adapter cable (VGA15->VGA15) to include the booster.

But then I'd mess about with electronics for fun without a second thought.

Thanks for your quick response :-)
I'd like electronics too, my only concern is on finding the needed IC in my area!
So I'm asking for opinions before to start searching! Tomorrow I'll run 150Km to find the IC.
After that, my last chance is ebay or some online electronic shop, but in this case I have to add the shipping fees that in most cases these are higher than the buyed components and furthermore I'll have to wait for delivery :-(

If all works well, I think that I'll integrate the mod inside the lcd because of enough room (as long as this mod have no side effects on the lcd operation).

I'll update the thread with any progress (I'm crossing my fingers!)